• DAY1SVR: Day 1 Convective Outlook

    From COD Weather Processor@1:2320/107 to wx-storm@lists.illinois.edu on Tuesday, March 31, 2026 20:02:06
    ACUS01 KWNS 312002
    SWODY1
    SPC AC 312000

    Day 1 Convective Outlook
    NWS Storm Prediction Center Norman OK
    0300 PM CDT Tue Mar 31 2026

    Valid 312000Z - 011200Z

    ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FROM THE
    MID-MISSISSIPPI VALLEY ACROSS THE OHIO VALLEY AND THE SOUTHERN GREAT LAKES...AND ACROSS WESTERN OKLAHOMA AND FAR NORTHWEST TEXAS...

    ...SUMMARY...
    Scattered severe thunderstorms with damaging wind gusts and large
    hail are expected today from the Mid Mississippi Valley across the
    Ohio Valley and southern Great Lakes. Isolated severe storms capable
    of large hail and damaging gusts are possible across western
    Oklahoma and far northwest Texas as well.

    ...20Z Update...
    The primary changes to the forecast were to adjust severe/thunder
    probabilities in the Upper Midwest given the progression of the cold
    front and impacts of earlier convection. The remainder of the
    forecast remains on track. See MD 308/309 for additional short-term
    mesoscale details.

    ..Wendt.. 03/31/2026

    .PREV DISCUSSION... /ISSUED 1107 AM CDT Tue Mar 31 2026/

    ...IL/IN/MI/OH...
    Multiple clusters of thunderstorms are ongoing late this morning
    over northeast IL and northwest IN. These storms have a history of
    hail, and are moving into an air mass that is warming/destabilizing.
    Relatively steep mid-level lapse rates and strong westerly flow
    aloft will promote and increasing risk of organized storms capable
    of hail and damaging wind gusts through the afternoon. See WW #78
    and MCD #305 for further details. This activity is expected to
    persist into the evening, spreading across much of northern OH with
    a continued severe risk.

    ...Southern NY/Northern PA into New England...
    Latest surface analysis shows an outflow boundary extending across
    northern PA. The air mass north of the boundary is rather cool and
    stable, but is expected to recover quickly this afternoon with
    strong southwesterly low-level winds and daytime heating. Most CAM
    solutions suggest thunderstorm activity over southeast Ontario will
    intensify and affect parts of southern NY/northern PA with a risk of
    locally damaging wind gusts and hail. A tornado or two is also
    possible. Storms may spread into southern New England by evening
    with a continued marginal severe threat.

    ...TX Panhandle/Western OK...
    Full sunshine will result in strong heating and steep low-level
    lapse rates along the dryline over the eastern TX Panhandle and
    western OK this afternoon. A surface cold front will surge
    southward into this region, with at least isolated thunderstorm
    development expected near the triple-point by late afternoon. These
    storms will track eastward into western OK through the evening.
    Forecast soundings suggest a favorable environment for damaging
    winds and hail with these storms.

    $$

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  • From COD Weather Processor@1:2320/107 to wx-storm@lists.illinois.edu on Wednesday, April 01, 2026 00:40:37
    ACUS01 KWNS 010040
    SWODY1
    SPC AC 010039

    Day 1 Convective Outlook
    NWS Storm Prediction Center Norman OK
    0739 PM CDT Tue Mar 31 2026

    Valid 010100Z - 011200Z

    ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FROM THE UPPER
    MIDWEST INTO THE CENTRAL APPALACHIANS...

    ...SUMMARY...
    Scattered severe thunderstorms with damaging wind gusts and large
    hail are expected this evening from the Midwest into the central
    Appalachians. Isolated severe storms capable of large hail and
    damaging gusts are also possible across western Oklahoma and far
    northwest Texas.

    ...Midwest/Central Appalachians/Mid Mississippi Valley...
    Water vapor imagery shows a mid-level zonal flow pattern over the
    north-central and northeastern U.S., with a low-amplitude trough
    located in the western Great Lakes. Scattered to numerous
    thunderstorms are ongoing near the axis of a 40 to 55 knot low-level
    jet from northern Indiana northeastward into the central
    Appalachians. Within this corridor, RAP forecast soundings have
    SBCAPE mostly in the 500 to 1000 J/kg range, with 0-6 km shear of 35
    to 45 knots, and 0-3 km lapse rates near 7 C/km. This will be
    favorable for multicell line segments capable of producing severe
    wind gusts this evening. A few supercells with isolated large hail
    and a marginal tornado threat will also be possible. As cells
    continue to increase in coverage this evening, the development of a larger-scale multicell line segment may occur. If this happens, then
    the wind-damage threat could increase into the mid to late
    evening...see MCD 314.

    Further southwest into parts of the mid Mississippi Valley,
    scattered thunderstorms are developing near an axis of instability
    where SBCAPE is around 1000 J/kg, according to the RAP. This area is
    further away from the mid-level jet in the Great Lakes. For this
    reason, lift and deep-layer shear are somewhat weaker in the mid
    Mississippi Valley suggesting that any severe threat will remain
    marginal this evening.

    ...Southern and Central Plains...
    A mid-level shortwave trough is evident on water vapor imagery over
    western Kansas and western Oklahoma. At the surface, a cold front is
    located from southeast Kansas extending southwestward into west
    Texas. A broken line of strong thunderstorms is ongoing near the
    front from southwest Oklahoma into northwest Texas. The nearest
    forecast sounding is at Childress, which has MLCAPE near 1500 J/kg,
    0-6 km shear around 40 knots and a 850-500 mb lapse rate near 8
    C/km. This should be favorable for an isolated large hail and
    wind-damage threat. The threat is expected to persist for a couple
    more hours.

    ..Broyles.. 04/01/2026

    $$

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  • From COD Weather Processor@1:2320/107 to wx-storm@lists.illinois.edu on Wednesday, April 01, 2026 05:50:11
    ACUS01 KWNS 010550
    SWODY1
    SPC AC 010548

    Day 1 Convective Outlook
    NWS Storm Prediction Center Norman OK
    1248 AM CDT Wed Apr 01 2026

    Valid 011200Z - 021200Z

    ...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF
    THE SOUTHERN AND CENTRAL PLAINS...

    ...SUMMARY...
    Severe thunderstorms with damaging wind gusts, large hail and a few
    tornadoes are likely across the southern and central Plains this
    afternoon and evening. Isolated strong to severe storms are also
    possible from parts of the Ohio Valley, central Appalachians and
    Mid-Atlantic.

    ...Southern and Central Plains...
    A mid-level shortwave trough will move quickly eastward across the
    Desert Southwest today and into the southern Rockies. At the
    surface, a moist airmass will be in place across the southern
    Plains. A quasi-stationary front will be located from near Childress northeastward into southeast Kansas, with a dryline extending
    southward into west-central Texas. To the southeast of the front,
    surface dewpoints in the lower to mid 60s F will contribute to
    moderate instability by afternoon, with MLCAPE increasing into the
    2000 to 3000 J/kg range. Convective initiation will take place in
    the late afternoon along the front and dryline, with a broken line
    of strong to severe storms moving eastward across the southern and
    central Plains.

    In addition to a favorable thermodynamic environment, deep-layer
    shear will gradually improve over the southern Plains as the
    mid-level trough approaches. RAP forecast soundings in western
    Oklahoma increase 0-6 km shear from about 25 knots at 21Z to near 40
    knots at 00Z, suggesting that environment will support supercell
    development in the late afternoon. Lapse rates in the 7 to 7.5 C/km
    range will be favorable for large hail with supercells, and
    hailstones greater than 2 inches will be possible. In addition, a
    tornado threat is expected to develop as low-level shear ramps up
    during the late afternoon and early evening. Any supercell that can
    form far enough away from other storms to maintain a relative long
    life cycle will be favored to produce tornadoes. If any supercell
    can become intense, then a strong tornado will be possible.
    Otherwise, cells are forecast to congeal into a line and move
    eastward across northwest Texas, west-central Oklahoma, eastern
    Kansas and western Missouri during the evening. The stronger storms
    within this line should be associated with severe wind gusts and
    isolated large hail. A QLCS tornado threat will also be likely,
    especially within the more intense bowing line segments.

    Further south into southwest Texas, isolated supercells with large
    hail are expected to develop to the east of a dryline. This threat
    should persist into the early to mid evening. A few strong wind
    gusts will also be possible.

    ...Ohio Valley/Mid-Atlantic...
    West-southwesterly mid-level flow will be in place over much of the
    eastern U.S. today. At the surface, a quasi-stationary front will be
    located in the Ohio Valley from southern Indiana east-northeastward
    into far southern Pennsylvania. Surface dewpoints in the upper 50s
    and lower 60s F to the south of the front will contribute to weak
    instability by early afternoon. Increasing low-level convergence
    near the front and warming surface temperatures will result in
    scattered thunderstorms during the afternoon. Several short line
    segments are expected to form and move eastward across the Ohio
    Valley into the central Appalachians. 0-6 km shear in the 25 to 35
    knot range and steep low-level lapse rates will support isolated
    severe storms with potential for damaging wind gusts. A low-end
    tornado threat will also be possible.

    ..Broyles/Squitieri.. 04/01/2026

    $$

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  • From COD Weather Processor@1:2320/107 to wx-storm@lists.illinois.edu on Wednesday, April 01, 2026 12:54:39
    ACUS01 KWNS 011253
    SWODY1
    SPC AC 011251

    Day 1 Convective Outlook
    NWS Storm Prediction Center Norman OK
    0751 AM CDT Wed Apr 01 2026

    Valid 011300Z - 021200Z

    ...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS ACROSS
    NORTHWEST TEXAS...WESTERN/CENTRAL OKLAHOMA...AND SOUTH-CENTRAL
    KANSAS...

    ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS PORTIONS OF THE
    MIDDLE OHIO VALLEY AND MID-ATLANTIC...

    ...SUMMARY...
    Severe thunderstorms with damaging wind gusts, large hail and a few
    tornadoes are likely across the southern and central Plains this
    afternoon and evening. Strong to severe storms are also possible
    from parts of the Ohio Valley, central Appalachians and
    Mid-Atlantic.

    ...Synopsis...
    Early morning radar and satellite imagery shows a cluster of
    thunderstorms moving through central MO, just to the north and east
    of a surface low over far southwest MO. Surface analysis shows a
    cold front extending from this low northeastward across the OH
    Valley and Northeast to another low over NH. A stationary boundary
    also extends southwestward from the southwest MO low across central
    and southwest OK, and northwest TX to another low over the Permian
    Basin. Thunderstorms are expected to focus on each of these
    boundaries today, particularly from the middle OH Valley into the
    Mid-Atlantic and over large portion of the central/southern Plains
    and Mid MS Valley. Severe thunderstorms are possible across these
    regions as well, with the highest severe thunderstorm coverage
    expected from northwest TX through western OK into south-central KS.

    ...Central/Southern Plains...
    Low-level moisture advection is anticipated across the southern
    Plains today as the shortwave trough currently moving through the
    southern Great Basin continues quickly eastward, reaching the
    central Plains by early tomorrow. General expectation is for the
    stationary boundary mentioned in the synopsis to push north as warm
    front and for mid 60s dewpoints to cover much of OK by the late
    afternoon. This increasing low-level moisture beneath steep lapse
    rates (over 7 to 7.5 deg C per 12Z soundings and recent
    mesoanalysis) will support moderate to strong buoyancy from
    southwest TX into much of central and western OK. Height falls
    attendant to the approaching shortwave will begin spreading over
    this destabilizing airmass by the early afternoon, combining with
    low-level convergence along the front and dryline to support
    convective initiation between 21Z and 00Z.

    Given the expectation that convective inhibition will be limited, if
    present at all, widespread development is anticipated from western
    OK into southwest TX. Kinematic profiles support supercells, but the
    persistent ascent and extensive nature of the convective initiation
    suggest that a discrete convective mode will be difficult to
    maintain and a quick transition to a convective line appears
    probable. As such, strong gusts appear to be the primary severe
    risk. Even so, steep lapse rates should still support large hail,
    even within the convective line. Very large hail (i.e. 2"+ in
    diameter) is possible if a discrete mode can be maintained. A
    discrete mode could also increase the tornado potential, but higher probabilities (i.e. 10%) were not introduced given the likely storm interactions and expected quick convective evolution into a line.
    Some tornado risk will still be present within the line,
    particularly during the 00-04Z period as low-level hodographs
    lengthen amid a strengthening low-level jet.

    This strengthening low-level jet is also expected to support a
    secondary area of thunderstorm development from northeast
    OK/southeast KS into central/southern MO during the late afternoon.
    Large hail (with some isolated instances of hail around 2") is the
    primary risk with these storms, most likely early in their
    convective cycles.

    ...Ohio Valley into Mid-Atlantic...
    Ongoing cluster over MO will gradually move eastward with time, with
    the airmass south of the front mentioned in the synopsis
    destabilizing throughout the day. This destabilization coupled with
    moderate westerly flow aloft could lead to a reintensification of
    this cluster and/or new development ahead of it. Vertical shear will
    be modest but still sufficient for bowing line segments capable of
    damaging gusts. Greatest storm coverage (and attendant greatest
    severe potential) is expected over the middle Ohio Valley and the
    Mid-Atlantic States.

    ..Mosier/Bentley.. 04/01/2026

    $$

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  • From COD Weather Processor@1:2320/107 to wx-storm@lists.illinois.edu on Wednesday, April 01, 2026 16:15:42
    ACUS01 KWNS 011615
    SWODY1
    SPC AC 011613

    Day 1 Convective Outlook
    NWS Storm Prediction Center Norman OK
    1113 AM CDT Wed Apr 01 2026

    Valid 011630Z - 021200Z

    ...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS ACROSS
    NORTHWEST TEXAS...WESTERN/CENTRAL OKLAHOMA...AND SOUTH-CENTRAL
    KANSAS...

    ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS OVER PORTIONS OF
    THE OHIO VALLEY AND MID-ATLANTIC...

    ...SUMMARY...
    Severe thunderstorms with damaging wind gusts, large hail and a few
    tornadoes are likely across the southern and central Plains this
    afternoon and evening. Strong to severe storms are also possible
    from parts of the Ohio Valley, central Appalachians and
    Mid-Atlantic.

    ...OK/TX...
    Water vapor imagery shows a potent shortwave trough moving across
    northern AZ. This feature will approach the surface dryline over
    west TX late this afternoon and evening, resulting in rapid and
    widespread thunderstorm development from the eastern TX Panhandle
    into western OK. Activity will build eastward through the evening
    with a risk of very large hail, damaging wind, and a few tornadoes.

    ...Northern OK/KS/Southwest MO...
    Latest surface analysis shows a weak boundary extending from
    southwest OK into southeast KS. This boundary will lift/mix
    northward today, resulting in rapid moistening/destabilization of
    the air mass. Most CAM solutions suggest the potential for the
    development of a few evening supercells in vicinity of this
    retreating boundary over north-central OK into southeast KS. Very
    large hail and a few tornadoes are possible.

    ...OH Valley into Mid-Atlantic...
    A well-defined surface boundary currently extends from southern OH
    into southern PA, with widespread clouds to the north and strong
    heating to the south. This strengthening baroclinic zone will
    provide the focus for thunderstorm development this afternoon and
    early evening. A cluster of thunderstorms is forecast by several
    CAM solutions to form over northeast KY/southern OH and track
    eastward through the afternoon, posing a risk of damaging wind
    gusts. Other more isolated strong storms are possible from
    southeast PA into the warm/moist air mass over parts of MD/VA, with
    a similar risk of gusty/damaging winds in the strongest cells.

    ..Hart/Wendt.. 04/01/2026

    $$

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  • From COD Weather Processor@1:2320/107 to wx-storm@lists.illinois.edu on Wednesday, April 01, 2026 19:59:45
    ACUS01 KWNS 011959
    SWODY1
    SPC AC 011957

    Day 1 Convective Outlook
    NWS Storm Prediction Center Norman OK
    0257 PM CDT Wed Apr 01 2026

    Valid 012000Z - 021200Z

    ...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF KANSAS...OKLAHOMA AND WESTERN NORTH TEXAS...

    ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS OVER PARTS OF THE
    OHIO VALLEY AND MID ATLANTIC...

    ...SUMMARY...
    Severe thunderstorms with damaging wind gusts, large hail and a few
    tornadoes are likely across the southern and central Plains this
    afternoon and evening. Strong to severe storms are also possible
    from parts of the Ohio Valley, central Appalachians and
    Mid-Atlantic.

    ...20z Update OK/KS/MO...
    Observational trends and model guidance continue to show rapid
    destabilization taking place this afternoon as a warm front
    gradually lifts northward across OK into southeastern KS and
    southwestern MO. Large-scale ascent is forecast to increase rapidly
    tonight as the primary upper trough over the Four Corners ejects
    eastward, aiding in storm development along a broad area of the
    front. Semi-discrete supercells and clusters are possible tonight
    before upscale growth takes place after 00z. The strong synoptic
    ascent should favor a rapid strengthening of low-level flow and
    shear. This would support a risk for damaging gusts and some
    tornadoes with remaining supercells or linear segments. Expand the
    5% tornado and 15% wind areas farther east into MO where CAM
    guidance shows storm persisting overnight.

    Farther southwest, no significant changes were made to the prior
    outlook. Scattered semi-discrete thunderstorm development remains
    likely along the dryline/front intersection across west/southwestern
    OK into western north TX this afternoon amid filtered heating of a
    moistening air mass. Initial supercells will pose risk for large
    hail and a couple tornadoes. The damaging wind threat (and possible
    some QLCS tornado risk) will likely increase after dark as storms
    congeal and spread northeastward beneath an intensifying 40-50 kt
    low-level jet.

    ...OH Valley and Mid Atlantic...
    Elsewhere, scattered thunderstorms are ongoing and expected to
    gradually increase in coverage through this evening along a frontal
    zone across the OH Valley into the Mid Atlantic. South of the front,
    moderate buoyancy and deep-layer shear will support some storm
    organization with supercells or organized clusters from northeast KY
    into southern OH and parts of WV/VA. Damaging gusts, and perhaps
    some hail are possible with the stronger storms.

    ..Lyons.. 04/01/2026

    .PREV DISCUSSION... /ISSUED 1113 AM CDT Wed Apr 01 2026/

    ...OK/TX...
    Water vapor imagery shows a potent shortwave trough moving across
    northern AZ. This feature will approach the surface dryline over
    west TX late this afternoon and evening, resulting in rapid and
    widespread thunderstorm development from the eastern TX Panhandle
    into western OK. Activity will build eastward through the evening
    with a risk of very large hail, damaging wind, and a few tornadoes.

    ...Northern OK/KS/Southwest MO...
    Latest surface analysis shows a weak boundary extending from
    southwest OK into southeast KS. This boundary will lift/mix
    northward today, resulting in rapid moistening/destabilization of
    the air mass. Most CAM solutions suggest the potential for the
    development of a few evening supercells in vicinity of this
    retreating boundary over north-central OK into southeast KS. Very
    large hail and a few tornadoes are possible.

    ...OH Valley into Mid-Atlantic...
    A well-defined surface boundary currently extends from southern OH
    into southern PA, with widespread clouds to the north and strong
    heating to the south. This strengthening baroclinic zone will
    provide the focus for thunderstorm development this afternoon and
    early evening. A cluster of thunderstorms is forecast by several
    CAM solutions to form over northeast KY/southern OH and track
    eastward through the afternoon, posing a risk of damaging wind
    gusts. Other more isolated strong storms are possible from
    southeast PA into the warm/moist air mass over parts of MD/VA, with
    a similar risk of gusty/damaging winds in the strongest cells.

    $$

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  • From COD Weather Processor@1:2320/107 to wx-storm@lists.illinois.edu on Thursday, April 02, 2026 01:02:49
    ACUS01 KWNS 020102
    SWODY1
    SPC AC 020100

    Day 1 Convective Outlook
    NWS Storm Prediction Center Norman OK
    0800 PM CDT Wed Apr 01 2026

    Valid 020100Z - 021200Z

    ...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS PORTIONS OF
    NORTHWEST TEXAS...OKLAHOMA...AND SOUTHEAST KANSAS...

    ...SUMMARY...
    Severe thunderstorms with damaging wind gusts, large hail and
    tornado potential will continue across the southern and central
    Plains this evening and overnight. Strong storms are also possible
    from parts of the Ohio Valley, central Appalachians and
    Mid-Atlantic.

    ... 01Z Update ...

    Severe thunderstorms with a history of damaging winds are currently
    located across southwest Oklahoma. This complex will continue to
    move northeast this evening, aided by mesoscale circulations
    associated with a mesolow/MCV across western Oklahoma. As the
    low-level jet increases this evening, an increase in tornado
    potential will be possible across portions of Tornado Watch #86. See
    Mesoscale Discussion #325 for more information.

    Elsewhere, clusters of strong-to-severe thunderstorms will be
    possible across southeast Kansas into southwest Missouri along a
    surface boundary. Although deep-layer shear is somewhat less than
    areas to the south and west, the presence of a low-level boundary,
    an increasing low-level jet, and sufficient low-level instability
    will continue to support some severe potential -- including
    tornadoes -- for several more hours.

    A hail and wind threat will also persist for several more hours
    across southwest Texas where MUCAPE values between 1000-1500 J/kg
    and deep-layer shear around 40 knots will support at least some
    supercell threat.

    ..Marsh.. 04/02/2026

    $$

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  • From COD Weather Processor@1:2320/107 to wx-storm@lists.illinois.edu on Thursday, April 02, 2026 06:04:17
    ACUS01 KWNS 020604
    SWODY1
    SPC AC 020602

    Day 1 Convective Outlook
    NWS Storm Prediction Center Norman OK
    0102 AM CDT Thu Apr 02 2026

    Valid 021200Z - 031200Z

    ...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS ACROSS EASTERN IOWA...NORTHERN ILLINOIS...AND FAR SOUTHERN WISCONSIN...

    ...SUMMARY...
    Severe thunderstorms capable of producing a few tornadoes appear
    probable across parts of eastern Iowa, northern Illinois, and
    southern Wisconsin this afternoon. Additionally, damaging
    thunderstorm winds will be possible from eastern Iowa northeast into
    Michigan.

    ... Overview ...

    A negatively tilted trough will quickly lift northward through the
    Plains and across the Great Lakes today and tonight. As this occurs,
    a modest surface low will race northeast from north-central Kansas
    this morning into Ontario by Friday morning. Attendant to this
    surface low, a west-east oriented warm front will lift northward
    across the Great Lakes during the day and a north-south cold front
    will push east across the region during the late afternoon and
    overnight.

    ... Eastern Iowa east-north into Michigan ...

    A strong low-level jet at the start of the forecast period will
    support widespread showers and thunderstorms across the area. The
    low-level jet will strengthen through the morning as the midlevel
    trough approaches and the H850 low intensifies. This will maintain
    showers and thunderstorms through at least midday across Iowa and
    Illinois before the H850 low moves far enough north and east for the
    core of the low-level jet to focus farther east, taking the
    precipitation with it.

    In the wake of the morning/early afternoon convection, a narrow
    corridor of destabilization should occur across central/eastern Iowa
    and northwest Illinois to the south of the warm front and east of
    the cold front. Scattered supercells are expected to develop along
    the cold front during the afternoon where MUCAPE in excess of 1000
    J/kg and deep-layer shear on the order of 45 knots exists. Strong
    low-level kinematic fields will support a tornado and wind threat
    with these initial storms, and, despite modest lapse-rates, the
    presence of supercells within a modestly unstable environment will
    support some hail potential.

    By late afternoon/early evening these supercells should move into a
    less stable environment characterized by decreasing CAPE but
    increasing low-level shear. Current expectation is that the initial
    discrete storms will eventually grow upscale into one or more linear
    segments, along the advancing cold front. Despite the decreasing
    instability, the strength of the low-level wind field will support a
    continued wind threat eastward into Lower Michigan during the
    evening and overnight hours.

    ... Northeast Arkansas, Southeast Missouri, western Tennessee, and
    western Kentucky ...

    Isolated thunderstorms will be possible during the afternoon along
    and ahead of the surface cold front, where modest warm-air advection
    is forecast to persist through the day. Despite weakening kinematic
    fields, deep-layer shear on the order of 30 knots and MUCAPE between
    1000-2000 J/kg will support at least some severe potential --
    including a tornado or two -- during the late afternoon and early
    evening.

    ..Marsh/Chalmers.. 04/02/2026

    $$

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  • From COD Weather Processor@1:2320/107 to wx-storm@lists.illinois.edu on Thursday, April 02, 2026 12:57:50
    ACUS01 KWNS 021257
    SWODY1
    SPC AC 021256

    Day 1 Convective Outlook
    NWS Storm Prediction Center Norman OK
    0756 AM CDT Thu Apr 02 2026

    Valid 021300Z - 031200Z

    ...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS EASTERN
    IOWA...NORTHERN ILLINOIS...AND FAR SOUTHERN WISCONSIN...

    ...SUMMARY...
    Severe thunderstorms capable of producing a few tornadoes appear
    probable across parts of eastern Iowa, northern Illinois, and
    southern Wisconsin this afternoon. Additionally, damaging
    thunderstorm winds will be possible from eastern Iowa northeast into
    Michigan.

    ...Synopsis...
    Early morning satellite and radar imagery show an extensive warm
    conveyor, with embedded showers and thunderstorms, extending from
    the southern Plains into the Upper Midwest, with some westward
    branching noted over the Mid MO Valley. This warm conveyor is
    associated with shortwave trough currently progressing through the
    central Plains. Recent surface analysis places a surface low just
    ahead of this wave over central KS, with a warm front extending
    eastward from the low into the middle OH Valley and a dryline
    extending south-southwestward from this low through the TX Trans
    Pecos.

    Expectation is for this shortwave to eject quickly northeastward
    throughout the day, maintaining a negative tilt as it progresses
    through the Mid MO Valley and Upper Midwest before ending the period
    over northeastern Ontario. The associated surface low will move
    quickly northeastward as well, progressing across southern and
    eastern IA and southern WI before occluding over upper MI tonight.
    Warm front attendant to this low will move northward as well,
    bringing low 60s dewpoints into eastern IA, northern IL, and
    southern WI before a cold front moves through. Strong to severe
    thunderstorms are possible along and ahead of the cold front over
    much of the Mid MS and Lower OH Valleys, with the highest potential
    for severe thunderstorms from eastern Iowa, northern IL, and far
    southern WI.

    ...Northern MO/Southern IA across southern WI/northern IL into Lower
    MI...
    Extensive area of showers and thunderstorms is currently ongoing
    from central TX into the Upper Midwest, within the warm conveyor
    mentioned in the synopsis. Moderate to strong southerly low-level
    flow exists within this warm sector. Progression of the negatively
    tilted shortwave and associated surface low mentioned in the
    synopsis will lead to a strengthening of this low-level flow, with
    attendant moisture advection into more of the Mid MS Valley. Some
    eastward displacement of the warm conveyor is anticipated, leaving
    the potential for airmass destabilization ahead of the surface low
    and cold front. This is supported by most of the guidance, which
    depicts a corridor of surface-based buoyancy and little to no
    convective inhibition from eastern IA/northern IL into central/east
    TX by the early afternoon.

    Best forcing for ascent within this corridor will be over the Upper
    Midwest and Mid MS Valley, particularly from southern/eastern IA
    into northern IL/southern WI, as both the shortwave and surface low
    move through the region. The strongest vertical shear will be over
    this region as well, supporting the potential for supercells with
    the initial, more cellular development. Very strong low-level shear
    supports a heightened tornado potential with any supercells,
    including the possibility of strong (EF2+) tornadoes. Given the
    linear forcing along the approaching cold front, a transition to a
    more linear storm mode is anticipated, although there is some
    uncertainty to how fast this transition occurs. The strength of the
    low-level flow supports a continued risk for tornadoes within any
    convective lines, but the primary hazard once any lines develop will
    become strong gusts. Kinematic fields are strong enough to support
    60 to 80 mph gusts. Additionally, despite weakening buoyancy, strong
    ascent and robust kinematic fields support the potential for
    damaging gusts across much of Lower MI later tonight.

    ...Mid MS and Lower OH Valleys into the Mid-South...
    As previously mentioned, showers and thunderstorms are currently
    ongoing from central TX into the Upper Midwest, within the extensive
    warm conveyor mentioned in the synopsis. There is some potential for reintensification of these showers and thunderstorms late this
    afternoon/early evening from central/eastern IL into the northeast
    AR/MO Bootheel, supported my modest destabilization and increasing
    ascent. Storm structures will likely be somewhat shallow, but strong
    flow will still support the potential for damaging gusts within any
    bowing line segments. A brief tornado is possible as well.

    Airmass destabilization is also anticipated west of this warm
    conveyor, but ahead of the cold front, from central IL into
    central/southern MO and northern AR. Much of this area will be
    displaced south and west of the departing shortwave trough and
    surface low, limiting large-scale ascent. However, some modest
    ascent is possible along a weak lagging upper trough, which could be
    enough to promote additional development. If updrafts can be
    maintained, parameters support the potential for strong to severe
    storms capable. Large hail is the primary risk, but a
    low-probability tornado risk exists as well.

    ..Mosier/Bentley.. 04/02/2026

    $$

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  • From COD Weather Processor@1:2320/107 to wx-storm@lists.illinois.edu on Thursday, April 02, 2026 16:15:21
    ACUS01 KWNS 021615
    SWODY1
    SPC AC 021613

    Day 1 Convective Outlook
    NWS Storm Prediction Center Norman OK
    1113 AM CDT Thu Apr 02 2026

    Valid 021630Z - 031200Z

    ...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS THIS AFTERNOON
    AND EVENING OVER PARTS OF EASTERN IOWA...NORTHERN ILLINOIS...AND
    SOUTHERN WISCONSIN....

    ...SUMMARY...
    Severe thunderstorms capable of producing a few tornadoes appear
    probable across parts of eastern Iowa, northern Illinois, and
    southern Wisconsin this afternoon. Additionally, damaging
    thunderstorm winds will be possible from eastern Iowa northeast into
    Michigan.

    ...IA/IL/MO/WI...
    Morning water vapor imagery shows a strong shortwave trough over
    northeast KS, with an associated mid-level jet and dry-slot rotating
    around the base of the trough into western MO. A deep surface low
    currently south of OMA will track northeastward across IA this
    afternoon, with a tight gradient of low-level moisture and
    instability along the track of the low. Very strong low-level shear
    and sufficient CAPE in the warm sector will pose a risk of
    fast-moving supercells capable of damaging winds, tornadoes
    (possibly strong), and hail. The area of greatest concern is over
    eastern IA into northern IL and far southern WI. Perhaps the
    biggest forecast uncertainty is the widespread cloud cover and
    limited diurnal destabilization, but the approaching dry slot may
    compensate by mid-afternoon and allow a period of afternoon heating.

    The coverage of storms with southward extent is uncertain across
    eastern MO and central/southern IL. Recent CAM solutions continue
    to show only widely scattered discrete development across this
    corridor. However, given the forecast of strong low-level shear and
    favorable synoptic forcing, those storms that do form would pose a
    risk of damaging winds and a few tornadoes.

    ...Eastern IL/IN/Lower MI...
    Strong southerly low-level winds will maintain 60s dewpoints across
    eastern IL/western IN, and result in the warm front lifting
    northward into southern Lower MI by this evening. This will provide
    a favorable environment for a few severe storms capable of damaging
    winds and perhaps a few tornadoes.

    ..Hart/Kerr.. 04/02/2026

    $$

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  • From COD Weather Processor@1:2320/107 to wx-storm@lists.illinois.edu on Thursday, April 02, 2026 19:57:52
    ACUS01 KWNS 021957
    SWODY1
    SPC AC 021956

    Day 1 Convective Outlook
    NWS Storm Prediction Center Norman OK
    0256 PM CDT Thu Apr 02 2026

    Valid 022000Z - 031200Z

    ...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS OVER PARTS OF
    EASTERN IOWA...NORTHERN ILLINOIS...AND SOUTHERN WISCONSIN...

    ...SUMMARY...
    Severe thunderstorms capable of producing a few tornadoes remain
    probable across parts of eastern Iowa, northern Illinois, and
    southern Wisconsin this afternoon and evening. Additionally,
    damaging thunderstorm winds will be possible from eastern Iowa
    northeast into Michigan.

    ...20z Update IA, IL, MO and southern WI...
    Rapid air mass modification is underway to the south of a warm front
    lifting northward across the western Great Lakes and upper Midwest.
    Clearing beneath the advancing mid-level dry slot may allow
    temperatures to warm into the low 70s, with surface dewpoints near
    60 F. This will support weak buoyancy amid very strong shear
    profiles (0-1 km SRH >300 m2/s2) from observed VADs and regional
    RAOBs.

    Scattered thunderstorms and supercells ongoing over northern MO and
    southern IA should mature and present a severe hazard over much of
    the ENH area as they spread northeastward through this evening. A
    few tornadoes (some strong and fast moving), hail and damaging gusts
    are expected. Additional storms may develop within the warm conveyor
    belt farther east across IL this afternoon/evening. Upscale growth
    into one or more clusters with damaging gusts and a couple tornadoes
    is the primary concern.

    The main change with the 20z update was to trim thunderstorm and
    severe probabilities to the west of the advancing cold front. See
    the prior discussion for more information.

    ..Lyons.. 04/02/2026

    .PREV DISCUSSION... /ISSUED 1113 AM CDT Thu Apr 02 2026/

    ...IA/IL/MO/WI...
    Morning water vapor imagery shows a strong shortwave trough over
    northeast KS, with an associated mid-level jet and dry-slot rotating
    around the base of the trough into western MO. A deep surface low
    currently south of OMA will track northeastward across IA this
    afternoon, with a tight gradient of low-level moisture and
    instability along the track of the low. Very strong low-level shear
    and sufficient CAPE in the warm sector will pose a risk of
    fast-moving supercells capable of damaging winds, tornadoes
    (possibly strong), and hail. The area of greatest concern is over
    eastern IA into northern IL and far southern WI. Perhaps the
    biggest forecast uncertainty is the widespread cloud cover and
    limited diurnal destabilization, but the approaching dry slot may
    compensate by mid-afternoon and allow a period of afternoon heating.

    The coverage of storms with southward extent is uncertain across
    eastern MO and central/southern IL. Recent CAM solutions continue
    to show only widely scattered discrete development across this
    corridor. However, given the forecast of strong low-level shear and
    favorable synoptic forcing, those storms that do form would pose a
    risk of damaging winds and a few tornadoes.

    ...Eastern IL/IN/Lower MI...
    Strong southerly low-level winds will maintain 60s dewpoints across
    eastern IL/western IN, and result in the warm front lifting
    northward into southern Lower MI by this evening. This will provide
    a favorable environment for a few severe storms capable of damaging
    winds and perhaps a few tornadoes.

    $$

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  • From COD Weather Processor@1:2320/107 to wx-storm@lists.illinois.edu on Friday, April 03, 2026 01:02:52
    ACUS01 KWNS 030102
    SWODY1
    SPC AC 030101

    Day 1 Convective Outlook
    NWS Storm Prediction Center Norman OK
    0801 PM CDT Thu Apr 02 2026

    Valid 030100Z - 031200Z

    ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PORTIONS OF
    THE SOUTHERN GREAT LAKES REGION...

    ...SUMMARY...
    Ongoing severe thunderstorms across the Great Lakes this evening
    will remain capable of producing damaging thunderstorm winds, a
    couple of tornadoes, and some hail into the overnight hours.

    ... 01Z Update ...

    A vigorous, negatively tilted trough continues to lift northeast
    across the Upper Great Lakes this evening. Ahead of this wave,
    strong ascent is supporting multiple clusters/bands of severe
    convection across the Great Lakes -- one currently across Indiana
    and Michigan within the cyclone's warm-conveyor belt and another
    across Illinois and Wisconsin along the combined Pacific front and
    dryline.

    Despite the loss of diurnal heating, strong large-scale ascent and
    low-level convergence along the front/dryline will support
    thunderstorms into the overnight. Although the overall intensity of
    the thunderstorms will gradually decrease with time, the strength of
    the low-level wind fields will support a continued wind threat into
    Lower Michigan overnight, with a modest QLCS-type tornado threat.

    ..Marsh.. 04/03/2026

    $$

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  • From COD Weather Processor@1:2320/107 to wx-storm@lists.illinois.edu on Friday, April 03, 2026 05:58:54
    ACUS01 KWNS 030558
    SWODY1
    SPC AC 030557

    Day 1 Convective Outlook
    NWS Storm Prediction Center Norman OK
    1257 AM CDT Fri Apr 03 2026

    Valid 031200Z - 041200Z

    ...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS ACROSS NORTHERN
    MISSOURI AN SOUTHERN IOWA...

    ...SUMMARY...
    Storms are expected to evolve into an extensive line by Friday
    evening from Iowa to Oklahoma and northwest Texas, with the primary
    threats of large hail and damaging winds. A few tornadoes and
    isolated very large hail will be possible from northern Missouri
    into southern Iowa with any sustained supercells.

    A midlevel trough, emanating from a previous TPV, will move across
    the northern US today and tonight. This feature will maintain a
    modest surface cyclone that will progress northeastward from central
    Kansas to southern Wisconsin by Saturday morning. As the surface low
    lifts northeast, a west-east orientate warm front will push
    northward toward Lower Michigan.

    ... Northern Missouri and Southern Iowa ...

    As the surface cyclone lifts northeast in response to increasing
    pressure falls in advance of the midlevel trough, southerly winds
    will draw low-level moisture northward, with low-to-mid 60Fs
    dewpoints possible along and south of the aforementioned warm front.
    Residual steep mid-level lapse rates and modest insolation will
    contribute to MLCAPE values up to 2000 J/kg (and MUCAPE values
    approach 3000 J/kg). Despite the low-level jet weakening through the
    day, deep-layer shear will be sufficient for supercells along and
    south of the warm front and east of the Pacific cold front/dryline.
    However, given persistent warm-air advection/isentropic ascent
    associated with the advancing warm front, concerns abound regarding
    the number of storms, storm interactions, and an overall messy storm
    mode evolution.

    If a more discrete mode emerges, the overall kinematic wind field
    would support sustained supercells and an increased tornado threat
    along both the Pacific Front/dryline and the northward moving warm
    front. Very large hail would also be possible. If a more linear mode
    emerges, the primary severe hazard would focus more on strong winds
    and a QLCS tornado threat. Of note, even with a more linear mode,
    uncertainty in the coverage of potential strong convective winds is
    low owing to a weakening low-level jet and storm interactions. The
    Level 3/Enhanced was kept at this time, but the need for a
    wind-driven Level 3/Enhanced will be revisited in subsequent
    forecasts.

    ... Central Illinois east into Ohio and north into Lower Michigan
    ...

    Thunderstorms will be possible along the northward moving warm front
    during the afternoon on Friday. Although there is uncertainty
    regarding the number/coverage of storms, the overall thermodynamic
    and kinematic fields would support the potential for hail and wind
    along and north of the warm front. Across the western portions of
    this area, a brief tornado threat would exist as any discrete
    supercells traverse through the warm frontal zone.

    ... Southeast Kansas/Southwest Missouri southwest toward Northwest
    Texas...

    Thunderstorms will develop southward from northern Missouri into
    Oklahoma during the afternoon as the Pacific cold front/dryline
    pushes east into an increasingly unstable airmass. At the same time,
    additional thunderstorms are likely to develop across Northwest
    Texas and southwest Oklahoma in association with a subtle
    perturbation within the subtropical jet. Forecast wind fields
    indicate low-level flow will be weaker here than areas farther north
    and east, and have pronounced weakness in the 3-6 km AGL range. The
    combination of this wind field and the widespread nature of the
    convection would lend itself to large hail and damaging winds as the
    main severe hazards, although a tornado cannot be ruled out with any
    discrete storm or along the leading edge of any organized linear
    segments.

    ... Southwest Texas ...

    Isolated thunderstorms will be possible during the afternoon/evening
    along the higher terrain and a surface dryline. Wind fields will
    support supercells capable of producing large hail and damaging
    winds. However uncertainty regarding overall storm coverage
    precludes a categorical upgrade to Level 2/Slight Risk.

    ..Marsh/Chalmers.. 04/03/2026

    $$

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  • From COD Weather Processor@1:2320/107 to wx-storm@lists.illinois.edu on Friday, April 03, 2026 12:42:55
    ACUS01 KWNS 031242
    SWODY1
    SPC AC 031240

    Day 1 Convective Outlook
    NWS Storm Prediction Center Norman OK
    0740 AM CDT Fri Apr 03 2026

    Valid 031300Z - 041200Z

    ...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS ACROSS NORTHERN
    MISSOURI AND SOUTHERN IOWA INTO WEST/NORTHWEST ILLINOIS...

    ...SUMMARY...
    A few tornadoes and isolated very large hail are possible late this
    afternoon and evening across northern Missouri into southern Iowa
    and north-central Illinois with any sustained supercells that
    develop. Storms are otherwise expected to evolve into an extensive
    line by Friday evening from Iowa to Oklahoma and northwest Texas,
    with the primary threats of large hail and damaging winds.

    ...Northern Missouri/southern Iowa/north-central Illinois...
    The shortwave trough emerging from the north-central High Plains
    this morning will spread east-northeastward toward the Upper Midwest
    through early Saturday. This will be accompanied by a strengthening
    (70+ kt) belt of cyclonically curved mid/high-level westerlies. A
    surface low across the south-central Plains will transition
    northeastward toward the Iowa/Illinois border vicinity tonight,
    while a warm front shifts northward from northern Missouri into Iowa
    and across northern portions of Illinois/Indiana, where low/middle
    60s F dewpoints will become common across the Midwest near and south
    of the warm front.

    Within the warm sector, residually steep mid-level lapse rates and
    modest insolation will contribute to MLCAPE values up to 2000 J/kg
    (and MUCAPE values approach 3000 J/kg). Deep-layer shear will be
    sufficient for supercells along and south of the warm front and east
    of the Pacific cold front/dryline. While the likelihood/extent of
    semi-discrete supercellular development remains a bit uncertain, the
    main potential for such will increase during the afternoon near the
    triple point around the Kansas/Missouri/Iowa border vicinity and
    eastward, potentially as far east into western/north-central
    Illinois in vicinity of the northward-shifting warm front.
    Semi-discrete development would offer tornado/very large hail
    potential, as well as a possible multi-round scenario of severe
    storms in some of this corridor via a more prevalent line of storms
    during the evening, with a damaging wind risk and some continued
    tornado potential as the low-level restrengthens.

    ...Northern Indiana to western portions of Pennsylvania/New York...
    Relatively strong westerlies atop the frontal zone, which will be
    more southeast-progressive as a cold front with eastward extent,
    will support at least isolated severe thunderstorms late this
    afternoon into evening, including a few supercells regionally.

    ...Southeast Kansas/Southwest Missouri to Northwest Texas...
    Thunderstorms will develop southward from northern Missouri into
    Oklahoma during the afternoon as the Pacific cold front/dryline
    advances southeastward into an increasingly unstable airmass. At the
    same time, additional thunderstorms are likely to develop across
    Northwest Texas and southwest Oklahoma in association with a subtle perturbation within the subtropical jet. Forecast wind fields
    indicate low-level flow will be weaker here than areas farther north
    and east. The combination of this wind field and the widespread
    nature of the convection would lend itself to large hail and
    damaging winds as the main severe hazards, although a tornado could
    occur with any discrete storm or along the leading edge of any
    organized linear segments.

    ...Southwest Texas...
    Isolated thunderstorms are expected by late afternoon and early
    evening in vicinity of the dry line and near some of the
    mountains/higher terrain. Wind fields will support supercells
    capable of producing large hail and localized severe-caliber winds.

    ..Guyer/Weinman.. 04/03/2026

    $$

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  • From COD Weather Processor@1:2320/107 to wx-storm@lists.illinois.edu on Friday, April 03, 2026 16:08:28
    ACUS01 KWNS 031608
    SWODY1
    SPC AC 031606

    Day 1 Convective Outlook
    NWS Storm Prediction Center Norman OK
    1106 AM CDT Fri Apr 03 2026

    Valid 031630Z - 041200Z

    ...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS THIS AFTERNOON
    AND EVENING OVER PARTS OF SOUTHERN IOWA...NORTHERN MISSOURI...AND
    WESTERN ILLINOIS....

    ...SUMMARY...
    Thunderstorms are expected to evolve into an extensive line this
    evening from Iowa to Oklahoma and northwest Texas, with the primary
    threats of large hail and damaging winds. A few tornadoes are also
    possible in any supercells that can form ahead of the line over
    parts of Iowa, Missouri, and central Illinois.

    ...MO/IA/IL...
    Latest surface analysis shows a low over northeast KS. This low
    will track northeastward across southern IA today, with the
    associated warm front lifting northward into northern IL. The air
    mass in the warm sector of the low will be relatively moist and
    unstable with dewpoints in the lower 60s and afternoon MLCAPE values
    of 2000 J/kg. Thunderstorms are expected to develop near the
    surface low in IA, and more widely scattered storms eastward along
    the warm front. A few supercells are possible across this region,
    with a concern for tornadoes, large hail, and damaging winds in the
    most intense cells.

    ...MO/KS/OK/TX...
    An extensive line of thunderstorms is expected to form along the
    cold front this afternoon from western MO into southeast KS and much
    of OK. Ample low-level moisture and CAPE will be present ahead of
    the storms, along with sufficient deep-layer shear for
    rotating/bowing storm structures. Large hail and damaging winds
    appear to be the main concern, but a tornado or two are also
    possible.

    ..Hart/Wendt.. 04/03/2026

    $$

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  • From COD Weather Processor@1:2320/107 to wx-storm@lists.illinois.edu on Friday, April 03, 2026 19:56:00
    ACUS01 KWNS 031955
    SWODY1
    SPC AC 031954

    Day 1 Convective Outlook
    NWS Storm Prediction Center Norman OK
    0254 PM CDT Fri Apr 03 2026

    Valid 032000Z - 041200Z

    ...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF
    SOUTHERN IOWA...NORTHERN MISSOURI AND WESTERN ILLINOIS....

    ...SUMMARY...
    Thunderstorms are expected to evolve into an extensive line this
    evening from Iowa to Oklahoma and northwest Texas, with the primary
    threats of large hail and damaging winds. A few tornadoes are also
    possible in any supercells that can form ahead of the line over
    parts of Iowa, Missouri, and central Illinois.

    ...20z update KS, MO IA and IL...
    Scattered thunderstorm development was ongoing this afternoon ahead
    of a weak surface low an associated cold front over the MO Valley.
    To the east, a broad and unstable warm sector exists south of a quasi-stationary front extending into eastern MO and IL. Moderate
    buoyancy and deep-layer shear will support a mix of supercells.
    Damaging winds and hail remain the most likely near the cold front
    as it moves eastward with a linear storm modes. A few tornadoes are
    also possible with more discrete cells and backed surface winds
    along the warm front farther east. The primary update to the
    forecast was to remove thunder and severe probabilities behind the
    cold front, otherwise the severe risk remains as is.

    ...Southern KS, OK and into TX...
    Scattered to numerous thunderstorms remain likely this afternoon and
    evening along the advancing cold front from southern KS, across much
    of OK and ahead of a dryline into west-central TX. South of the
    primary upper trough and stronger flow aloft, overall forcing will
    be weaker. Still, forecast soundings and observation trends show
    moderate destabilization and sufficient deep-layer shear for
    supercells and organized clusters/line segments. Hail (some 2+ in)
    is possible with initial supercells before upscale growth is
    expected to take place with the surging cold front.

    A locally more favorable zone for large hail, damaging gusts and a
    tornado or two may develop across parts of central and southern OK
    if semi discrete supercells or stronger bowing structures can become organized/maintained this afternoon/evening.

    ...OH Valley...
    A moist and unstable air mass will support scattered thunderstorms
    across the OH valley this afternoon. Isolated damaging gusts are
    possible with multi-cell storms/clusters amid modest vertical shear.
    Storms should weaken this evening with the loss of diurnal heating.

    ..Lyons.. 04/03/2026

    .PREV DISCUSSION... /ISSUED 1106 AM CDT Fri Apr 03 2026/

    ...MO/IA/IL...
    Latest surface analysis shows a low over northeast KS. This low
    will track northeastward across southern IA today, with the
    associated warm front lifting northward into northern IL. The air
    mass in the warm sector of the low will be relatively moist and
    unstable with dewpoints in the lower 60s and afternoon MLCAPE values
    of 2000 J/kg. Thunderstorms are expected to develop near the
    surface low in IA, and more widely scattered storms eastward along
    the warm front. A few supercells are possible across this region,
    with a concern for tornadoes, large hail, and damaging winds in the
    most intense cells.

    ...MO/KS/OK/TX...
    An extensive line of thunderstorms is expected to form along the
    cold front this afternoon from western MO into southeast KS and much
    of OK. Ample low-level moisture and CAPE will be present ahead of
    the storms, along with sufficient deep-layer shear for
    rotating/bowing storm structures. Large hail and damaging winds
    appear to be the main concern, but a tornado or two are also
    possible.

    $$

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  • From COD Weather Processor@1:2320/107 to wx-storm@lists.illinois.edu on Saturday, April 04, 2026 00:58:32
    ACUS01 KWNS 040058
    SWODY1
    SPC AC 040056

    Day 1 Convective Outlook
    NWS Storm Prediction Center Norman OK
    0756 PM CDT Fri Apr 03 2026

    Valid 040100Z - 041200Z

    ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FROM NORTHWEST
    TEXAS NORTHEAST INTO SOUTHEAST IOWA AND EAST INTO CENTRAL
    ILLINOIS...

    ...SUMMARY...
    Thunderstorms continue to evolve into an extensive line this evening
    from Iowa to Oklahoma and northwest Texas. Damaging winds, hail, and
    a couple of tornadoes remain possible through the overnight.

    ... 01Z Update ...

    Thunderstorms continue to develop along and ahead of an advancing
    cold front this evening. These storms should continue to increase in
    number, growing upscale into an extensive linear MCS from Northwest
    Texas northeastward into southern Iowa. Despite nocturnal
    stabilization of the boundary layer, forcing along the cold front,
    MUCAPE between 1000-2000 J/kg, and sufficient vertical shear should
    support a continued hail and wind threat into the overnight hours,
    especially across the southern portion of this area where updrafts
    appear to be more robust than areas farther north. Given the moist
    low-levels and a modest uptick in the low-level jet, a couple of
    tornadoes may still occur as well.

    Additional thunderstorms have developed eastward along the warm
    front draped across southern Iowa east across Illinois, Indiana,
    Ohio, and Pennsylvania. MUCAPE and vertical shear decrease with
    eastward extent along the warm front, organized thunderstorms within
    the frontal zone should support an localized hail and wind threat
    for a few more hours. A tornado or two could also be realized with
    any discrete/semi-discrete cell that can increase its resonance time
    in the frontal zone, especially across central Illinois where better instability and vertical shear exist.

    ..Marsh.. 04/04/2026

    $$

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  • From COD Weather Processor@1:2320/107 to wx-storm@lists.illinois.edu on Saturday, April 04, 2026 06:01:04
    ACUS01 KWNS 040601
    SWODY1
    SPC AC 040559

    Day 1 Convective Outlook
    NWS Storm Prediction Center Norman OK
    1259 AM CDT Sat Apr 04 2026

    Valid 041200Z - 051200Z

    ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS SOUTHEAST LOWER MICHIGAN...MUCH OF OHIO...AND PORTIONS OF WESTERN PENNSYLVANIA AND
    NEW YORK....

    ...SUMMARY...
    Strong-to-severe storms will be possible from eastern Texas
    northeastward toward the Lower Great Lakes. Sporadic damaging winds
    will be the most likely severe hazard throughout this corridor, with
    the greatest likelihood across the Lower Great Lakes.

    ... Synopsis ...

    A midlevel trough is forecast to move from the northern Plains into
    Ontario on Saturday As this happens, a surface low should lift
    northward from northern Illinois/southern Wisconsin into Ontario as
    well and a surface cold front will accelerate eastward across the
    Great Lakes and be approaching the East Coast by Sunday morning. To
    the southwest, the cold front will not progress as quickly, but
    should advance south and east through the day.

    ... Southeast Lower Michigan, Ohio, Western Pennsylvania, and
    western New York ...

    As the surface low lifts northward into Canada on Saturday, showers
    and thunderstorms are expected to be ongoing along and ahead of the
    trailing composite cold front/convective outflow. At the same time,
    a surface warm front will lift slowly northward across Lower
    Michigan. To the south of this front, and ahead of the cold
    front/outflow, a moist airmass, characterized by low-to-mid 60Fs
    dewpoints should be in place. Despite the strongest large-scale
    ascent being displaced to the north and west of the warm sector and
    weak midlevel lapse rates atop the warm sector, pockets of
    insolation should be sufficient to destabilize the environment
    enough to support some convective redevelopment along and ahead of
    the composite outflow/cold front. Modest instability will combine
    with seasonably strong low-level wind fields to support a convective
    wind threat and an isolated tornado threat along the leading edge of
    any sustained linear segments.

    ... Tennessee Valley southwest to eastern Texas ...

    Widespread thunderstorms are expected to be ongoing across the
    western portions of this area at the start of the forecast period.
    These thunderstorms will likely be driven by convergence along the east/southeast moving composite cold front/convective outflow
    boundary, with the exact western edge of any severe threat
    demarcated by where this boundary is located at the start of the
    forecast period. Seasonably high precipitable water values should
    support some threat for strong wind gusts in the most intense
    thunderstorm cores. These thunderstorms are expected to continue
    through the day, despite weakening large-scale ascent and vertical
    wind shear as the midlevel low pulls farther away. Given the
    seasonably high precipitable water values, modest insolation should
    support MUCAPE values between 500 and 1000 J/kg (perhaps as high as
    1500 J/kg) across portions of Texas, Louisiana, and Mississippi.
    This may support a re-intensification of ongoing convection which
    would be capable of sporadic damaging downbursts

    ..Marsh/Chalmers.. 04/04/2026

    $$

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  • From COD Weather Processor@1:2320/107 to wx-storm@lists.illinois.edu on Saturday, April 04, 2026 12:42:09
    ACUS01 KWNS 041242
    SWODY1
    SPC AC 041240

    Day 1 Convective Outlook
    NWS Storm Prediction Center Norman OK
    0740 AM CDT Sat Apr 04 2026

    Valid 041300Z - 051200Z

    ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS THE LOWER
    GREAT LAKES/OHIO VALLEY...

    ...SUMMARY...
    Severe storms capable of damaging winds and a tornado risk are
    expected across parts of the Lower Great Lakes and middle/upper Ohio
    River Valley, mainly this afternoon through early evening. Other
    more isolated severe storms may occur across the Tennessee Valley,
    Lower Mississippi Valley, and eastern part of Texas.

    ...Ohio/Eastern Indiana/Lower Michigan to Pennsylvania/New York...
    A shortwave trough over the Upper Midwest early today will continue northeastward toward the upper Great Lakes through tonight.
    Cyclonically influenced strengthening deep-layer southwesterlies
    (50+ kt 700 mb) will overspread Indiana/Michigan toward the Lower
    Great Lakes, atop a steadily moistening/heating warm-sector boundary
    layer along and north of the Ohio River.

    This will be ahead of a surface low and cold front, that is
    considerably augmented by generally weakening thunderstorms and
    prevalent lingering clouds/outflows through the pre-dawn hours.
    These residual factors cast uncertainty regarding the magnitude of
    today's overall potential, but a formidable flow field and
    guidance-advertised heating/steady diurnal destabilization will
    still be supportive of at least some severe potential regionally as
    storms redevelop and intensify this afternoon. This includes
    damaging wind potential, particularly given the magnitude of low/mid-tropospheric winds and boundary layer mixing, with some
    tornado threat as well, mainly in vicinity of the triple
    point/nearby warm front. Overall storm intensities should decrease
    by mid/late evening, owing to nocturnal boundary-layer influences
    and the primary upper-level system spreading away from the region.

    ...Tennessee Valley/Lower Mississippi Valley/Texas ...
    While diminishing in intensity overnight, showers/thunderstorms
    remain extensive and prevalent from the Mid-South/Ozarks
    southwestward into North Texas, as a synoptic cold front otherwise
    continues to progress southeastward across these regions. While
    details are complexified by considerable cloud cover and lingering
    storms, multiple corridors of reinvigorating storms should
    materialize this afternoon where more appreciable cloud
    breaks/heating occur. Downbursts/locally damaging winds will be the
    primary severe hazard, but this is currently expected to be on a
    relatively isolated/episodic basis.

    ..Guyer/Weinman.. 04/04/2026

    $$

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  • From COD Weather Processor@1:2320/107 to wx-storm@lists.illinois.edu on Saturday, April 04, 2026 16:27:07
    ACUS01 KWNS 041627
    SWODY1
    SPC AC 041625

    Day 1 Convective Outlook
    NWS Storm Prediction Center Norman OK
    1125 AM CDT Sat Apr 04 2026

    Valid 041630Z - 051200Z

    ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF
    THE LOWER GREAT LAKES/OHIO VALLEY...

    ...SUMMARY...
    Severe thunderstorms capable of producing scattered damaging winds
    and perhaps a tornado or two appear possible across parts of the
    Lower Great Lakes and middle/upper Ohio River Valley region this
    afternoon through early evening. Other more isolated strong to
    severe thunderstorms may occur across parts of the the Tennessee
    Valley, Lower Mississippi Valley, and central/east/south Texas.

    ...Midwest/Lower Michigan to Pennsylvania and Western New York...
    An upper trough over the Upper Midwest late this morning will
    continue moving northeastward toward the upper Great Lakes through
    tonight. Strengthening deep-layer southwesterlies (with 50+ kt
    present at 700 mb) will overspread IN/MI toward the Lower Great
    Lakes atop a gradually moistening/heating boundary layer along and
    north of the Ohio River.

    This will occur ahead of a surface low over WI/MI and convectively reinforced/southeastward-developing cold front that will impact
    parts of the Midwest/OH Valley this afternoon. Recent visible
    satellite trends showing clearing across much of OH into northwest
    PA suggest sufficient heating and modest diurnal destabilization
    will support at least some severe potential regionally as
    thunderstorms redevelop and intensify this afternoon along/ahead of
    the cold front. Given steepening low-lapse rates and enhanced
    low/mid-level southwesterly flow, scattered severe/damaging winds
    should be the main threat. But, there may also be some potential for
    a tornado or two as well, mainly in vicinity of the triple
    point/nearby warm front that will extend eastward into central PA.
    Overall updraft intensities should decrease by mid to late evening,
    owing to stabilizing/nocturnal boundary-layer influences, and the
    primary upper trough/low moving northeastward away from the region.

    ...Tennessee Valley into the Lower Mississippi Valley/Texas...
    Showers and occasional thunderstorms remain extensive this morning
    from the Mid-South southwestward into northeast TX, as a surface
    cold front continues to progress southeastward across these areas.
    Even with considerable cloud cover and poor lapse rates aloft ahead
    of this ongoing activity, multiple corridors of reinvigorated
    convective clusters should develop this afternoon where some cloud breaks/filtered heating can occur. Downbursts with locally damaging
    winds should be the primary severe hazard, but this threat is
    expected to remain relatively isolated given lessening deep-layer
    shear with southward extent into the lower MS Valley/TX.

    ..Gleason/Wendt.. 04/04/2026

    $$

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  • From COD Weather Processor@1:2320/107 to wx-storm@lists.illinois.edu on Saturday, April 04, 2026 20:02:09
    ACUS01 KWNS 042002
    SWODY1
    SPC AC 042000

    Day 1 Convective Outlook
    NWS Storm Prediction Center Norman OK
    0300 PM CDT Sat Apr 04 2026

    Valid 042000Z - 051200Z

    ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF
    NORTHERN OHIO INTO NORTHWESTERN PENNSYLVANIA AND SOUTHWESTERN NEW
    YORK STATE...

    ...SUMMARY...
    Severe thunderstorms capable of producing scattered damaging winds
    and perhaps a tornado or two remain possible across parts of the
    Lower Great Lakes and middle/upper Ohio River Valley region this
    afternoon through early evening. Other more isolated strong to
    severe thunderstorms may occur across parts of the the Tennessee
    Valley, Lower Mississippi Valley, and central/east/south Texas.

    ...20z Update Great Lakes Region...
    A band of thunderstorms ahead of the eastward progressing cold front
    will continue across northern OH this afternoon before moving into
    western PA and southwest NY this evening. Diurnal steepening of
    low-level lapse rates amid fairly strong, but unidirectional flow
    aloft will continue to support a risk for damaging gusts. A brief
    tornado also remains possible with any rotating elements, especially
    near the southern shores of Lake Erie near the stalled warm
    front/lake boundary. Have trimmed severe and thunder probabilities
    behind the front over IN where the risk has decreased.

    ...TN Valley to the Southeast and South TX...
    Ahead of the southern portions of the cold front, a warm, moist, and
    unstable air mass will support widespread thunderstorm activity from
    parts of the TN Valley, Southeast and into South TX. In the absence
    of steep mid-level lapse rates and stronger vertical shear
    (especially with southward extent), storm organization should be
    transient and limited. Still, the moist environment and some veering
    winds the lowest few km could support an occasional stronger or
    briefly rotating storm. Any clustering could support occasional
    damaging gusts or small hail with stronger updrafts near the front.
    The outlook remains valid with only minor adjustments to the western
    extent of thunder and severe probabilities.

    ..Lyons.. 04/04/2026

    .PREV DISCUSSION... /ISSUED 1125 AM CDT Sat Apr 04 2026/

    ...Midwest/Lower Michigan to Pennsylvania and Western New York...
    An upper trough over the Upper Midwest late this morning will
    continue moving northeastward toward the upper Great Lakes through
    tonight. Strengthening deep-layer southwesterlies (with 50+ kt
    present at 700 mb) will overspread IN/MI toward the Lower Great
    Lakes atop a gradually moistening/heating boundary layer along and
    north of the Ohio River.

    This will occur ahead of a surface low over WI/MI and convectively reinforced/southeastward-developing cold front that will impact
    parts of the Midwest/OH Valley this afternoon. Recent visible
    satellite trends showing clearing across much of OH into northwest
    PA suggest sufficient heating and modest diurnal destabilization
    will support at least some severe potential regionally as
    thunderstorms redevelop and intensify this afternoon along/ahead of
    the cold front. Given steepening low-lapse rates and enhanced
    low/mid-level southwesterly flow, scattered severe/damaging winds
    should be the main threat. But, there may also be some potential for
    a tornado or two as well, mainly in vicinity of the triple
    point/nearby warm front that will extend eastward into central PA.
    Overall updraft intensities should decrease by mid to late evening,
    owing to stabilizing/nocturnal boundary-layer influences, and the
    primary upper trough/low moving northeastward away from the region.

    ...Tennessee Valley into the Lower Mississippi Valley/Texas...
    Showers and occasional thunderstorms remain extensive this morning
    from the Mid-South southwestward into northeast TX, as a surface
    cold front continues to progress southeastward across these areas.
    Even with considerable cloud cover and poor lapse rates aloft ahead
    of this ongoing activity, multiple corridors of reinvigorated
    convective clusters should develop this afternoon where some cloud breaks/filtered heating can occur. Downbursts with locally damaging
    winds should be the primary severe hazard, but this threat is
    expected to remain relatively isolated given lessening deep-layer
    shear with southward extent into the lower MS Valley/TX.

    $$

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  • From COD Weather Processor@1:2320/107 to wx-storm@lists.illinois.edu on Sunday, April 05, 2026 01:01:40
    ACUS01 KWNS 050101
    SWODY1
    SPC AC 050059

    Day 1 Convective Outlook
    NWS Storm Prediction Center Norman OK
    0759 PM CDT Sat Apr 04 2026

    Valid 050100Z - 051200Z

    ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS PORTIONS
    OF THE NORTHERN APPALACHIANS AND FAR SOUTHERN TEXAS...

    ...SUMMARY...
    A couple of damaging gusts remain possible across the northern
    Appalachians this evening, and an instance or two of hail/wind may
    accompany one of the stronger storms in Deep South Texas.

    ...Synopsis...
    A pronounced mid-level trough continues to progress eastward over
    the Great Lakes, with surface lee troughing prevalent over the
    Appalachians and points east. A cold front continues to sweep
    eastward across the OH/TN Valleys into southern TX, preceded by
    enough buoyancy to support mainly general thunderstorms. A couple of
    stronger thunderstorms may still occur over the northern
    Appalachians and far southern TX.

    ...PA into the southern Great Lakes...
    Ahead of the surface cold front, scant buoyancy (e.g. a few hundred
    J/kg MLCAPE) remains in place per regional 00Z observed soundings.
    Most of the CAPE is constrained in the 850-600 mb layer, which may
    support a few strong low topped cells within bands of convection,
    aided by strong low-level shear, as shown by the soundings. 0-3 km
    SRH remains in the 200-300 m2/s2 range. As such, while the severe
    threat is expected to remain sparse at best given poor buoyancy, the
    strong low-level shear suggests that an additional damaging gust
    cannot be completely ruled out.

    ...Deep-South Texas...
    Multicells continue to propagate southward ahead of a cold front,
    where ample buoyancy remains in place. While vertical wind shear is
    poor, 2000+ J/kg MLCAPE, driven by 70 F dewpoints beneath 7+ C/km
    mid-level lapse rates (per the 00Z BRO observed sounding), indicates
    the potential for a sparse severe hail/gust instance before storms
    dissipate in the next few hours.

    ..Squitieri.. 04/05/2026

    $$

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  • From COD Weather Processor@1:2320/107 to wx-storm@lists.illinois.edu on Sunday, April 05, 2026 05:50:39
    ACUS01 KWNS 050550
    SWODY1
    SPC AC 050548

    Day 1 Convective Outlook
    NWS Storm Prediction Center Norman OK
    1248 AM CDT Sun Apr 05 2026

    Valid 051200Z - 061200Z

    ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS FOR THE
    CAROLINAS TO THE MID-ATLANTIC REGION...

    ...SUMMARY...
    Thunderstorms with isolated damaging wind gusts will be possible
    this afternoon afternoon from the eastern Carolinas to the
    Mid-Atlantic region.

    ...Synopsis...
    A mid-level trough will impinge on the East Coast as upper ridging
    builds over the Interior West today. This upper air pattern will
    support a surface trough and accompanying cold front moving offshore
    over the East Coast as surface high pressure becomes established to
    the west of the Appalachians, over much of the CONUS. Low-level
    moisture along the East Coast will promote thunderstorm potential
    ahead of the cold front given associated deep-layer lifting. A few
    strong thunderstorms are possible across the Carolinas into the
    Mid-Atlantic, where deep-layer ascent and vertical wind shear will
    be strongest.

    ...Carolinas into the Mid-Atlantic...
    By late morning into early afternoon, breaks in the clouds from
    central NC to the NJ shoreline will contribute to boundary layer
    mixing, along with destabilization (given the presence of 60+ F
    surface dewpoints). 6 C/km mid-level lapse rates overspreading this
    boundary layer will result in tall, thin CAPE profiles. A few
    hundred J/kg MLCAPE may develop along the Mid-Atlantic shoreline,
    with up to 1000 J/kg MLCAPE possible over the eastern Carolinas. As
    the surface cold front approaches by early afternoon, a line of
    storms should develop along the cold front. Modestly curved
    low-level hodographs should support some organization of the squall
    line, with a few damaging gusts possible during the afternoon.

    ..Squitieri/Chalmers.. 04/05/2026

    $$

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  • From COD Weather Processor@1:2320/107 to wx-storm@lists.illinois.edu on Sunday, April 05, 2026 12:44:41
    ACUS01 KWNS 051244
    SWODY1
    SPC AC 051242

    Day 1 Convective Outlook
    NWS Storm Prediction Center Norman OK
    0742 AM CDT Sun Apr 05 2026

    Valid 051300Z - 061200Z

    ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS THE CAROLINAS/MID-ATLANTIC REGION...

    ...SUMMARY...
    Thunderstorms with isolated damaging wind gusts are possible this
    afternoon across the eastern Carolinas and Mid-Atlantic region.

    ...Carolinas/Delmarva/Mid-Atlantic States...
    Multiple subtle mid-level perturbations over the Midwest, within the
    base of the broad upper trough centered over Canada/Great Lakes,
    will progress east-northeastward with steady height falls and
    strengthening flow aloft particularly for the Mid-Atlantic region
    and Delmarva. Prevalent showers/some thunderstorms early today will
    accompany an east/southeastward-moving cold front, but cloud breaks
    should allow for pre-frontal heating particularly across the coastal
    plain over the Carolinas and far southeast Virginia.

    A few hundred J/kg MLCAPE may develop along the Mid-Atlantic
    shoreline, with up to 1000 J/kg MLCAPE possible over the eastern
    Carolinas. As the surface cold front approaches by early afternoon,
    a line of storms should develop and intensify along the cold front.
    Modestly curved low-level hodographs should support linearly
    organizing clusters/bands of storms, with a few damaging wind gusts
    possible during the afternoon.

    ...Upper Midwest...
    While low-level moisture will be rather limited, thermodynamic
    profiles may be sufficiently supportive of a few lightning flashes
    late this afternoon and early evening across parts of southern Minnesota/northern Iowa into western Wisconsin in vicinity of a southeastward-spreading front. Gusty winds may also occur with this
    convection in the presence of a well-mixed boundary layer and
    strengthening northwesterly winds aloft.

    ..Guyer/Weinman.. 04/05/2026

    $$

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  • From COD Weather Processor@1:2320/107 to wx-storm@lists.illinois.edu on Sunday, April 05, 2026 16:12:12
    ACUS01 KWNS 051612
    SWODY1
    SPC AC 051610

    Day 1 Convective Outlook
    NWS Storm Prediction Center Norman OK
    1110 AM CDT Sun Apr 05 2026

    Valid 051630Z - 061200Z

    ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF
    THE EASTERN CAROLINAS AND COASTAL MID-ATLANTIC...

    ...SUMMARY...
    Thunderstorms with isolated damaging winds may occur this afternoon
    across the eastern Carolinas and parts of the Mid-Atlantic region.

    ...Carolinas/Mid-Atlantic...
    Within the base of a broad upper trough centered over eastern Canada
    and the Great Lakes, multiple subtle mid-level perturbations over
    the Midwest will develop east-northeastward across the Mid-Atlantic
    and Carolinas today. Ongoing showers will accompany an east/southeastward-moving surface cold front, but some cloud breaks
    will allow for filtered pre-frontal heating, particularly across the
    coastal plain over the eastern Carolinas and far southeast VA.

    Up to 100-300 J/kg of MLCAPE should develop across the coastal
    Mid-Atlantic, with 500-1000 J/kg MLCAPE possible over the eastern
    Carolinas where greater heating should occur. A broken line of
    low-topped thunderstorms will develop along/ahead of the cold front
    this afternoon as it moves east-southeastward. Modestly curved
    low-level hodographs and 25-35 kt of deep-layer shear should support clusters/bands of convection, with isolated damaging wind gusts
    possible where low-level lapse rates can become steepened. However,
    poor mid-level lapse rates and generally weak instability are
    expected to limit updraft strength and the overall severe threat.

    ...Upper Midwest...
    While low-level moisture will remain quite meager, cold temperatures
    aloft and very weak MUCAPE may support a few lightning flashes late
    this afternoon and early evening across parts of southeast MN into
    northeast IA and southwest WI near a southeastward-moving front.
    Gusty winds may occur with this convection in the presence of a
    well-mixed boundary layer and strengthening northwesterly winds
    aloft. But with minimal instability forecast, the overall severe
    threat is expected to remain low.

    ..Gleason/Wendt.. 04/05/2026

    $$

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  • From COD Weather Processor@1:2320/107 to wx-storm@lists.illinois.edu on Sunday, April 05, 2026 19:54:46
    ACUS01 KWNS 051954
    SWODY1
    SPC AC 051953

    Day 1 Convective Outlook
    NWS Storm Prediction Center Norman OK
    0253 PM CDT Sun Apr 05 2026

    Valid 052000Z - 061200Z

    ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS PORTIONS
    OF THE EASTERN CAROLINAS...

    ...SUMMARY...
    Thunderstorms with isolated damaging winds may occur this afternoon
    across the eastern Carolinas.

    ...20z Update...
    Latest radar and lightning data shows a band of pre-frontal
    convection moving across the Carolinas and far southeast VA. This
    activity will continue to pose an isolated wind damage threat for
    the next few hours before moving offshore by early evening. 5% wind probabilities have been adjusted accordingly, and the 10% general
    thunder probability highlights regions with remaining MUCAPE ahead
    of the approaching cold front. See the previous discussion below for
    additional details.

    ..Moore.. 04/05/2026

    .PREV DISCUSSION... /ISSUED 1110 AM CDT Sun Apr 05 2026/

    ...Carolinas/Mid-Atlantic...
    Within the base of a broad upper trough centered over eastern Canada
    and the Great Lakes, multiple subtle mid-level perturbations over
    the Midwest will develop east-northeastward across the Mid-Atlantic
    and Carolinas today. Ongoing showers will accompany an east/southeastward-moving surface cold front, but some cloud breaks
    will allow for filtered pre-frontal heating, particularly across the
    coastal plain over the eastern Carolinas and far southeast VA.

    Up to 100-300 J/kg of MLCAPE should develop across the coastal
    Mid-Atlantic, with 500-1000 J/kg MLCAPE possible over the eastern
    Carolinas where greater heating should occur. A broken line of
    low-topped thunderstorms will develop along/ahead of the cold front
    this afternoon as it moves east-southeastward. Modestly curved
    low-level hodographs and 25-35 kt of deep-layer shear should support clusters/bands of convection, with isolated damaging wind gusts
    possible where low-level lapse rates can become steepened. However,
    poor mid-level lapse rates and generally weak instability are
    expected to limit updraft strength and the overall severe threat.

    ...Upper Midwest...
    While low-level moisture will remain quite meager, cold temperatures
    aloft and very weak MUCAPE may support a few lightning flashes late
    this afternoon and early evening across parts of southeast MN into
    northeast IA and southwest WI near a southeastward-moving front.
    Gusty winds may occur with this convection in the presence of a
    well-mixed boundary layer and strengthening northwesterly winds
    aloft. But with minimal instability forecast, the overall severe
    threat is expected to remain low.

    $$

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  • From COD Weather Processor@1:2320/107 to wx-storm@lists.illinois.edu on Monday, April 06, 2026 05:43:16
    ACUS01 KWNS 060543
    SWODY1
    SPC AC 060541

    Day 1 Convective Outlook
    NWS Storm Prediction Center Norman OK
    1241 AM CDT Mon Apr 06 2026

    Valid 061200Z - 071200Z

    ...NO SEVERE THUNDERSTORM AREAS FORECAST...

    ...SUMMARY...
    Isolated to scattered thunderstorms are expected today across the
    Florida Peninsula, and portions of the Four Corners, northern
    Rockies, and eastern Great Lakes. No severe threat is forecast.

    ...Synopsis...
    A broad mid-level trough will begin exiting the Northeast and
    overspreading the Atlantic as another mid-level trough impinges on
    the Pacific Northwest and a lower amplitude impulse traverses the
    Southwest today. Much of the northern, central, and eastern CONUS
    will be dominated by surface high pressure while surface lee
    troughing, with dry low-level trajectories, takes place over the
    southern High Plains. As such, convective potential will be limited
    over the much of the U.S. with few exceptions. A few embedded
    mid-level impulses, accompanied by cooler temperatures aloft, will
    foster enough lift amid scant buoyancy to encourage a few lightning
    flashes across the northern Rockies, Four Corners region, and the
    eastern Great Lakes today.

    The best chance for organized thunderstorm potential will be over
    the FL Peninsula, where ample low-level moisture will exist in
    proximity to a stalled frontal boundary. Afternoon peak heating will
    support scattered thunderstorm development amid tall, thin CAPE
    profiles, but relatively poor vertical wind shear. While strong
    gusts may accompany some of the deeper storm cores, the threat for
    severe storms appears too low for the inclusion of severe
    wind-driven probabilities at this time.

    ..Squitieri/Chalmers.. 04/06/2026

    $$

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  • From COD Weather Processor@1:2320/107 to wx-storm@lists.illinois.edu on Monday, April 06, 2026 12:50:19
    ACUS01 KWNS 061250
    SWODY1
    SPC AC 061248

    Day 1 Convective Outlook
    NWS Storm Prediction Center Norman OK
    0748 AM CDT Mon Apr 06 2026

    Valid 061300Z - 071200Z

    ...NO SEVERE THUNDERSTORM AREAS FORECAST...

    ...SUMMARY...
    Isolated to scattered thunderstorms are expected today across the
    Florida Peninsula, and portions of the Four Corners, northern
    Rockies, and eastern Great Lakes. While a few strong storms may
    occur across the central/southern Florida Peninsula, organized
    severe potential is expected to remain low.

    ...Synopsis...
    The East will remain influenced by longwave troughing, while
    westerly quasi-zonal upper flow prevails elsewhere. Much of the
    northern, central, and eastern CONUS will be dominated by surface
    high pressure while surface lee troughing, with dry low-level
    trajectories, takes place over the southern High Plains.
    Thunderstorms are expected mainly this afternoon across the Florida
    Peninsula. A few embedded mid-level impulses, accompanied by cooler temperatures aloft, will foster enough lift amid scant buoyancy to
    encourage a few lightning flashes across the northern Rockies, Four
    Corners region, and the eastern Great Lakes today.

    ...Central/southern Florida Peninsula...
    Ample insolation/heating should occur today along and south of the slow-southward progressing front. This heating combined with
    easterly low-level winds should focus convergence and scattered
    thunderstorm development this afternoon across the interior
    peninsula. With the upstream shortwave trough not influencing the
    region until later tonight, mid-level lapse rates will remain
    relatively poor with weak deep-layer shear. Regardless, steepening
    low-level lapse rates should lead to increasing storm coverage and
    intensity this afternoon, particularly across the interior, and a
    few of these pulse-type storms could produce strong
    downburst-related gusty winds. However, it currently appears that severe-caliber wind gust potential will remain limited given the
    marginality of the overall scenario.

    ..Guyer/Weinman.. 04/06/2026

    $$

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  • From COD Weather Processor@1:2320/107 to wx-storm@lists.illinois.edu on Monday, April 06, 2026 16:18:21
    ACUS01 KWNS 061618
    SWODY1
    SPC AC 061616

    Day 1 Convective Outlook
    NWS Storm Prediction Center Norman OK
    1116 AM CDT Mon Apr 06 2026

    Valid 061630Z - 071200Z

    ...NO SEVERE THUNDERSTORM AREAS FORECAST...

    ...SUMMARY...
    Isolated to scattered thunderstorms are expected today across the
    Florida Peninsula and portions of the Southwest, Pacific Northwest,
    and eastern Great Lakes. While a few strong storms may occur across
    the central/southern Florida Peninsula, organized severe potential
    should remain low.

    ...Synopsis and Discussion...
    Mean longwave troughing will remain over the eastern COUNS today,
    while a weak mid-level shortwave trough advances eastward across the
    Gulf towards the FL Peninsula by late tonight. At the surface, high
    pressure centered over the southern Plains to TN/OH Valleys will
    maintain offshore low-level trajectories and limited low-level
    moisture over a large majority of the CONUS. Still, isolated
    lightning flashes may occur today across parts of the eastern Great
    Lakes, Southwest, and Pacific Northwest in association with weak
    mid-level perturbations amid the presence of sufficient MUCAPE and
    modest lift.

    Greater low-level moisture (mid 60s to low 70s surface dewpoints)
    will remain confined along/south of a cold front draped across the
    central FL Peninsula. Isolated to scattered thunderstorms are
    expected to develop this afternoon across central/south FL as
    daytime heating erodes lingering MLCIN, especially across interior
    areas. With the low-amplitude shortwave trough remaining well to the
    west over the Gulf through the day, weak low/mid-level winds and
    meager deep-layer shear over land will likely limit updraft
    organization and severe potential. Still, occasional strong/gusty
    downburst winds may occur with the more robust cores as low-level
    lapse rates become steepened with continued diurnal heating.

    ..Gleason/Wendt.. 04/06/2026

    $$

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  • From COD Weather Processor@1:2320/107 to wx-storm@lists.illinois.edu on Monday, April 06, 2026 19:22:22
    ACUS01 KWNS 061922
    SWODY1
    SPC AC 061920

    Day 1 Convective Outlook
    NWS Storm Prediction Center Norman OK
    0220 PM CDT Mon Apr 06 2026

    Valid 062000Z - 071200Z

    ...NO SEVERE THUNDERSTORM AREAS FORECAST...

    ...SUMMARY...
    Isolated to scattered thunderstorms are expected today across the
    Florida Peninsula and portions of the Southwest, Pacific Northwest,
    and eastern Great Lakes. While a few strong storms may occur across
    the central/southern Florida Peninsula, organized severe potential
    should remain low.

    ...20z Update...
    No changes are need to the current D1 Convective Outlook. See
    previous discussion below for more information.

    ..Thornton.. 04/06/2026

    .PREV DISCUSSION... /ISSUED 1116 AM CDT Mon Apr 06 2026/

    ...Synopsis and Discussion...
    Mean longwave troughing will remain over the eastern COUNS today,
    while a weak mid-level shortwave trough advances eastward across the
    Gulf towards the FL Peninsula by late tonight. At the surface, high
    pressure centered over the southern Plains to TN/OH Valleys will
    maintain offshore low-level trajectories and limited low-level
    moisture over a large majority of the CONUS. Still, isolated
    lightning flashes may occur today across parts of the eastern Great
    Lakes, Southwest, and Pacific Northwest in association with weak
    mid-level perturbations amid the presence of sufficient MUCAPE and
    modest lift.

    Greater low-level moisture (mid 60s to low 70s surface dewpoints)
    will remain confined along/south of a cold front draped across the
    central FL Peninsula. Isolated to scattered thunderstorms are
    expected to develop this afternoon across central/south FL as
    daytime heating erodes lingering MLCIN, especially across interior
    areas. With the low-amplitude shortwave trough remaining well to the
    west over the Gulf through the day, weak low/mid-level winds and
    meager deep-layer shear over land will likely limit updraft
    organization and severe potential. Still, occasional strong/gusty
    downburst winds may occur with the more robust cores as low-level
    lapse rates become steepened with continued diurnal heating.

    $$

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  • From COD Weather Processor@1:2320/107 to wx-storm@lists.illinois.edu on Tuesday, April 07, 2026 00:47:56
    ACUS01 KWNS 070047
    SWODY1
    SPC AC 070046

    Day 1 Convective Outlook
    NWS Storm Prediction Center Norman OK
    0746 PM CDT Mon Apr 06 2026

    Valid 070100Z - 071200Z

    ...NO SEVERE THUNDERSTORM AREAS FORECAST...

    ...SUMMARY...
    A few thunderstorms remain possible this evening across portions of
    the Pacific Northwest, Desert Southwest, and Florida Peninsula.

    ...Synopsis...
    A broad mid-level trough continues to progress across the Northeast,
    with upper ridging persisting over the Northwest, and a
    low-amplitude impulse impinging on the Southwest this evening.
    Across the Northwest and Southwest, colder air aloft is supporting
    scant buoyancy, which will continue to promote the potential for a
    couple of lightning flashes through early tonight. Thunderstorms
    continue to benefit from a moist, unstable environment across the
    central and southern FL Peninsula. Storms should gradually weaken
    this evening with the onset of nocturnal cooling.

    ..Squitieri.. 04/07/2026

    $$

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  • From COD Weather Processor@1:2320/107 to wx-storm@lists.illinois.edu on Tuesday, April 07, 2026 04:55:59
    ACUS01 KWNS 070455
    SWODY1
    SPC AC 070454

    Day 1 Convective Outlook
    NWS Storm Prediction Center Norman OK
    1154 PM CDT Mon Apr 06 2026

    Valid 071200Z - 081200Z

    ...NO SEVERE THUNDERSTORM AREAS FORECAST...

    ...SUMMARY...
    Isolated to scattered thunderstorms are expected today across parts
    of the Florida Peninsula, the southern Rockies, and northern High
    Plains. Severe thunderstorms are not expected.

    ...Synopsis...
    A mid-level trough will eject over the Atlantic while another
    pronounced mid-level trough rapidly traverses the northern Rockies
    today. Meanwhile, multiple low-amplitude impulses traversing
    relatively zonal upper flow will overspread the Southwest and the FL
    Peninsula. Across the Southern Rockies, enough lift amid cool air
    aloft (and thus scant buoyancy) should accompany the aforementioned low-amplitude mid-level impulse to support isolated to potentially
    scattered thunderstorm development. Scattered thunderstorms may also
    develop across the FL Peninsula along sea-breeze boundaries given a
    moist, heated low-level airmass. Scattered high-based/low-topped
    storms are likely across the northern High Plains with the approach
    of the upper trough. Storms will develop atop a deep and dry
    boundary layer, but with scant buoyancy. Given the dry boundary
    layer, gusty conditions may accompany the stronger storms. However,
    the severe wind threat currently appears too low for the
    introduction of a Category 1/Marginal risk at this time.

    ..Squitieri/Chalmers.. 04/07/2026

    $$

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  • From COD Weather Processor@1:2320/107 to wx-storm@lists.illinois.edu on Tuesday, April 07, 2026 12:35:57
    ACUS01 KWNS 071235
    SWODY1
    SPC AC 071234

    Day 1 Convective Outlook
    NWS Storm Prediction Center Norman OK
    0734 AM CDT Tue Apr 07 2026

    Valid 071300Z - 081200Z

    ...NO SEVERE THUNDERSTORM AREAS FORECAST...

    ...SUMMARY...
    Isolated to scattered thunderstorms are expected today across parts
    of the Florida Peninsula, the southern Rockies, and northern High
    Plains. Severe thunderstorm potential is currently expected to
    remain low.

    ...Synopsis...
    Split/nearly zonal upper-level flow will prevail across most of the
    CONUS to the south of an amplifying trough from the Canadian Rockies southeastward toward the northern High Plains, and in the wake of
    low-amplitude troughs crossing both New England and Florida today.

    ...Florida Peninsula...
    Scattered thunderstorms should increase across the Florida Peninsula
    into the afternoon, influenced by the passing mid-level trough and
    sea-breeze convergence in the presence of a very moist airmass. A
    few of the storms across the southern Florida Peninsula could
    produce locally strong thunderstorm winds, but severe potential
    should remain relatively low.

    ...Northern High Plains...
    Isolated high-based storms are expected across the northern High
    Plains, including eastern Montana into western North Dakota, aided
    by the approach of the aforementioned upper trough. Storms will
    develop atop a relatively dry/well-mixed boundary layer, but with
    very limited buoyancy overall. Given the dry boundary layer and
    strengthening mid-tropospheric winds, strong and gusty winds may
    accompany this convection during the late afternoon until around
    sunset.

    ..Guyer/Weinman.. 04/07/2026

    $$

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  • From COD Weather Processor@1:2320/107 to wx-storm@lists.illinois.edu on Tuesday, April 07, 2026 16:22:30
    ACUS01 KWNS 071622
    SWODY1
    SPC AC 071620

    Day 1 Convective Outlook
    NWS Storm Prediction Center Norman OK
    1120 AM CDT Tue Apr 07 2026

    Valid 071630Z - 081200Z

    ...NO SEVERE THUNDERSTORM AREAS FORECAST...

    ...SUMMARY...
    Isolated to potentially scattered thunderstorms should occur today
    across parts of the central/southern Florida Peninsula,
    southern/central Rockies/High Plains, and northern High Plains.
    Organized severe thunderstorm potential appears low.

    ...Synopsis and Discussion...
    A mid-level shortwave trough will move east-southeastward today from
    British Columbia/Alberta to the northern Rockies/High Plains. Strong
    mid-level winds will accompany this shortwave trough, and a
    deep/well-mixed boundary layer is expected to develop across parts
    of eastern MT and vicinity by this afternoon with diurnal heating.
    However, low-level moisture will remain quite limited, with surface
    dewpoints currently in the 20s to mid 30s across the northern High
    Plains. This will hinder the development of any more than weak
    MLCAPE by mid to late afternoon, although high-based convection
    capable of producing occasional lightning flashes and strong/gusty
    winds may occur. Given expectations for moisture and related
    instability to remain quite meager, have not included low severe
    wind probabilities across the northern High Plains with this update.

    A weak mid-level shortwave trough will continue to advance eastward
    across the FL Peninsula through the afternoon. Isolated to perhaps
    scattered thunderstorms remain possible, mainly across parts of
    south FL along and south of a convectively reinforced front. Prior
    convection and ongoing cloud cover across the central/southern FL
    Peninsula will probably hinder more robust diurnal heating this
    afternoon. Still, locally gusty downdraft winds and small hail may
    occur with the stronger cores that can develop, before convection
    eventually focuses offshore by this evening.

    Isolated to widely scattered thunderstorms also appear possible
    across parts of the southern/central Rockies and adjacent High
    Plains through this evening, but weak instability across these
    regions are expected to preclude severe thunderstorms.

    ..Gleason.. 04/07/2026

    $$

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  • From COD Weather Processor@1:2320/107 to wx-storm@lists.illinois.edu on Tuesday, April 07, 2026 19:48:02
    ACUS01 KWNS 071947
    SWODY1
    SPC AC 071946

    Day 1 Convective Outlook
    NWS Storm Prediction Center Norman OK
    0246 PM CDT Tue Apr 07 2026

    Valid 072000Z - 081200Z

    ...NO SEVERE THUNDERSTORM AREAS FORECAST...

    ...SUMMARY...
    Isolated to widely scattered thunderstorms remain possible across
    parts of the central/southern Florida Peninsula, southern/central
    Rockies/High Plains, and northern High Plains today and tonight.
    Organized severe thunderstorm potential appears low.

    ...20z Update...
    The only change was to trim thunder probabilities over parts of the
    southern FL Peninsula. Isolated storms remain possible south of the
    front over the Keys tonight. While a brief stronger thunderstorm
    remains possible across south FL, weak mid-level lapse rates and
    modest vertical shear will continue to limit severe potential before
    convection moves offshore this afternoon. Otherwise, the outlook
    remains unchanged, see the previous discussion.

    ..Lyons.. 04/07/2026

    .PREV DISCUSSION... /ISSUED 1120 AM CDT Tue Apr 07 2026/

    ...Synopsis and Discussion...
    A mid-level shortwave trough will move east-southeastward today from
    British Columbia/Alberta to the northern Rockies/High Plains. Strong
    mid-level winds will accompany this shortwave trough, and a
    deep/well-mixed boundary layer is expected to develop across parts
    of eastern MT and vicinity by this afternoon with diurnal heating.
    However, low-level moisture will remain quite limited, with surface
    dewpoints currently in the 20s to mid 30s across the northern High
    Plains. This will hinder the development of any more than weak
    MLCAPE by mid to late afternoon, although high-based convection
    capable of producing occasional lightning flashes and strong/gusty
    winds may occur. Given expectations for moisture and related
    instability to remain quite meager, have not included low severe
    wind probabilities across the northern High Plains with this update.

    A weak mid-level shortwave trough will continue to advance eastward
    across the FL Peninsula through the afternoon. Isolated to perhaps
    scattered thunderstorms remain possible, mainly across parts of
    south FL along and south of a convectively reinforced front. Prior
    convection and ongoing cloud cover across the central/southern FL
    Peninsula will probably hinder more robust diurnal heating this
    afternoon. Still, locally gusty downdraft winds and small hail may
    occur with the stronger cores that can develop, before convection
    eventually focuses offshore by this evening.

    Isolated to widely scattered thunderstorms also appear possible
    across parts of the southern/central Rockies and adjacent High
    Plains through this evening, but weak instability across these
    regions are expected to preclude severe thunderstorms.

    $$

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  • From COD Weather Processor@1:2320/107 to wx-storm@lists.illinois.edu on Wednesday, April 08, 2026 01:02:34
    ACUS01 KWNS 080102
    SWODY1
    SPC AC 080100

    Day 1 Convective Outlook
    NWS Storm Prediction Center Norman OK
    0800 PM CDT Tue Apr 07 2026

    Valid 080100Z - 081200Z

    ...NO SEVERE THUNDERSTORM AREAS FORECAST...

    ...SUMMARY...
    Isolated thunderstorms remain possible tonight over the northern and
    southern High Plains. Severe thunderstorms are not expected.

    ...Synopsis...
    A mid-level trough continues to progress across the northern
    Rockies, providing enough mechanical lift amid cool temperatures
    aloft to support isolated high-based thunderstorms atop a dry
    boundary layer. A low-amplitude mid-level impulse will also continue
    to traverse the northern Rockies, supporting scattered lightning
    flashes given the presence of scant buoyancy. These storms should
    gradually diminish through the evening as boundary-layer
    stabilization from nocturnal cooling takes place.

    ..Squitieri.. 04/08/2026

    $$

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  • From COD Weather Processor@1:2320/107 to wx-storm@lists.illinois.edu on Wednesday, April 08, 2026 05:58:35
    ACUS01 KWNS 080558
    SWODY1
    SPC AC 080556

    Day 1 Convective Outlook
    NWS Storm Prediction Center Norman OK
    1256 AM CDT Wed Apr 08 2026

    Valid 081200Z - 091200Z

    ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF
    WESTERN AND CENTRAL KANSAS...

    ...SUMMARY...
    A few strong thunderstorms may develop across western into central
    Kansas this afternoon and evening, with an instance or two of severe
    wind and hail possible.

    ...Synopsis...
    A mid-level trough will traverse the north-central CONUS today,
    supporting modest surface troughing across the Plains states.
    Despite initially meager low-level moisture return, storms may
    develop along a frontal boundary over the central Plains by late
    afternoon. A few of which may be strong. Otherwise, isolated to
    scattered thunderstorms may develop along sea-breeze boundaries over
    the FL Peninsula, as was with the upper trough over the Upper MS
    Valley. A couple of lightning flashes may also occur over northern
    CA surrounding areas as an upper trough impinges on the coastline.

    ...Central into western Kansas...
    By afternoon peak heating, clear skies and robust heating of the
    boundary layer will result in convective temperatures being reached
    along/just ahead of a frontal boundary, which is poised to drift
    southward through late afternoon. Convective initiation is likely
    around or after 20Z, when 30+ F T/Td spreads should be in place.
    High-based multicells will be the likely storm mode, as strong
    northwesterly flow aloft will contribute to elongated, straight
    hodographs. The strongest storms may produce a couple of severe
    gusts and perhaps an instance or two of hail.

    ..Squitieri/Chalmers.. 04/08/2026

    $$

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  • From COD Weather Processor@1:2320/107 to wx-storm@lists.illinois.edu on Wednesday, April 08, 2026 12:47:08
    ACUS01 KWNS 081247
    SWODY1
    SPC AC 081245

    Day 1 Convective Outlook
    NWS Storm Prediction Center Norman OK
    0745 AM CDT Wed Apr 08 2026

    Valid 081300Z - 091200Z

    ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF
    KANSAS...

    ...SUMMARY...
    Isolated severe thunderstorms may develop across western and central
    Kansas late this afternoon and early evening, with hail and locally
    severe wind gusts possible.

    ...Western/central Kansas...
    The region will be glancingly influenced by an eastward-progressing
    upper trough over the northern Plains. Ample insolation and robust
    heating of a boundary layer, characterized by limited moisture (40s
    F dewpoints), will result in convective temperatures being reached
    by peak heating near a southeastward-moving front. Isolated to
    widely scattered convective initiation is expected around or after
    20Z, when 30+ F T/Td spreads will be in place. High-based multicells
    will be the likely storm mode, as strong northwesterly flow aloft
    will contribute to elongated, straight hodographs. The strongest
    storms may produce hail and severe wind gusts on an isolated basis.

    ...Southern Florida...
    A couple of stronger storms with gusty winds could again occur
    today, mainly across the southeast part of the Florida Peninsula
    this afternoon. Any severe threat should remain relatively marginal
    and localized given the overall setup and thermodynamic environment.

    ..Guyer/Weinman.. 04/08/2026

    $$

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  • From COD Weather Processor@1:2320/107 to wx-storm@lists.illinois.edu on Wednesday, April 08, 2026 16:12:08
    ACUS01 KWNS 081612
    SWODY1
    SPC AC 081610

    Day 1 Convective Outlook
    NWS Storm Prediction Center Norman OK
    1110 AM CDT Wed Apr 08 2026

    Valid 081630Z - 091200Z

    ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF
    KANSAS...

    ...SUMMARY...
    Isolated severe thunderstorms may develop across parts of Kansas
    late this afternoon and early evening, with hail and locally severe
    wind gusts possible.

    ...Kansas...
    A strong upper trough/low over the northern Plains and south-central
    Canada will move eastward today towards the Upper Midwest/Great
    Lakes, and eventually spread into Ontario by late tonight. At the
    surface, an occluded low will develop eastward in tandem with the
    upper trough/low, while a cold front extending southwestward into
    the central Plains continues moving slowly southward through this
    evening. Limited low-level moisture is expected to exist ahead of
    the front by late this afternoon across KS, with late morning
    surface observations and short-term guidance both suggesting surface
    dewpoints will likely remain in the mid 30s to no more than mid 40s.
    A well-mixed boundary layer will likely develop with ample daytime
    heating across the narrow warm sector, with MLCAPE perhaps peaking
    in the 250-500 J/kg range around 21-23Z in parts of western/central
    KS. MLCIN is forecast to become minimal in this time frame, and weak
    low-level convergence along the front may be enough to aid isolated thunderstorm development across this area.

    While stronger flow aloft associated with the upper-level trough/low
    will remain displaced to the north of KS, modest enhancement to the
    mid-level westerlies may still support around 25-35 kt of deep-layer
    shear. This should be sufficient for some updraft organization with
    any thunderstorms that can develop and be sustained. The primary
    uncertainty remains how many thunderstorms will form given overall
    modest large-scale ascent amid weak instability. Still, some risk
    for isolated hail and locally severe gusts remains apparent with the
    strongest multicell cores. The Marginal Risk has been maintained
    across KS with no changes.

    ...Central/South Florida...
    20-30 kt mid-level westerlies will overlie weak low-level easterlies
    today across parts of the central/southern Florida Peninsula.
    Resultant modest effective bulk shear would conditionally support
    updraft organization, but poor mid-level lapse rates noted on the
    12Z TBW and KEY observed soundings should generally limit updraft
    strength. Still, isolated to locally scattered thunderstorms should
    develop this afternoon, and preferentially focus along/near the
    Atlantic Coast sea breeze. Small hail and gusty winds may occur with
    the strongest cores, but the overall severe threat appears too
    limited/isolated to include any probabilities at this time.

    ..Gleason/Wendt.. 04/08/2026

    $$

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  • From COD Weather Processor@1:2320/107 to wx-storm@lists.illinois.edu on Wednesday, April 08, 2026 19:48:41
    ACUS01 KWNS 081948
    SWODY1
    SPC AC 081946

    Day 1 Convective Outlook
    NWS Storm Prediction Center Norman OK
    0246 PM CDT Wed Apr 08 2026

    Valid 082000Z - 091200Z

    ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS WESTERN
    AND CENTRAL KANSAS...

    ...SUMMARY...
    Isolated severe thunderstorms may develop across parts of Kansas
    late this afternoon and early evening, with hail and locally severe
    wind gusts possible.

    ...20z Update KS...
    The prior outlook remains valid with no changes. High-based
    thunderstorms remain possible late this afternoon and this evening
    ahead of the cold front in western and central KS. Steep low and
    mid-level lapse rates should be sufficient for modest
    destabilization amid limited boundary-layer moisture (dewpoints in
    the 40s F). Despite the limited buoyancy, a few stronger multi-cell
    clusters capable of isolated severe gusts and some small hail are
    possible.

    Elsewhere, isolated thunderstorms remain possible across parts of
    FL, the West Coast and northern Plains through tonight. Weak
    buoyancy and poor overlap with vertical shear should limit severe
    potential. See the previous discussion for more information.

    ..Lyons.. 04/08/2026

    .PREV DISCUSSION... /ISSUED 1110 AM CDT Wed Apr 08 2026/

    ...Kansas...
    A strong upper trough/low over the northern Plains and south-central
    Canada will move eastward today towards the Upper Midwest/Great
    Lakes, and eventually spread into Ontario by late tonight. At the
    surface, an occluded low will develop eastward in tandem with the
    upper trough/low, while a cold front extending southwestward into
    the central Plains continues moving slowly southward through this
    evening. Limited low-level moisture is expected to exist ahead of
    the front by late this afternoon across KS, with late morning
    surface observations and short-term guidance both suggesting surface
    dewpoints will likely remain in the mid 30s to no more than mid 40s.
    A well-mixed boundary layer will likely develop with ample daytime
    heating across the narrow warm sector, with MLCAPE perhaps peaking
    in the 250-500 J/kg range around 21-23Z in parts of western/central
    KS. MLCIN is forecast to become minimal in this time frame, and weak
    low-level convergence along the front may be enough to aid isolated thunderstorm development across this area.

    While stronger flow aloft associated with the upper-level trough/low
    will remain displaced to the north of KS, modest enhancement to the
    mid-level westerlies may still support around 25-35 kt of deep-layer
    shear. This should be sufficient for some updraft organization with
    any thunderstorms that can develop and be sustained. The primary
    uncertainty remains how many thunderstorms will form given overall
    modest large-scale ascent amid weak instability. Still, some risk
    for isolated hail and locally severe gusts remains apparent with the
    strongest multicell cores. The Marginal Risk has been maintained
    across KS with no changes.

    ...Central/South Florida...
    20-30 kt mid-level westerlies will overlie weak low-level easterlies
    today across parts of the central/southern Florida Peninsula.
    Resultant modest effective bulk shear would conditionally support
    updraft organization, but poor mid-level lapse rates noted on the
    12Z TBW and KEY observed soundings should generally limit updraft
    strength. Still, isolated to locally scattered thunderstorms should
    develop this afternoon, and preferentially focus along/near the
    Atlantic Coast sea breeze. Small hail and gusty winds may occur with
    the strongest cores, but the overall severe threat appears too
    limited/isolated to include any probabilities at this time.

    $$

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  • From COD Weather Processor@1:2320/107 to wx-storm@lists.illinois.edu on Thursday, April 09, 2026 00:58:12
    ACUS01 KWNS 090058
    SWODY1
    SPC AC 090056

    Day 1 Convective Outlook
    NWS Storm Prediction Center Norman OK
    0756 PM CDT Wed Apr 08 2026

    Valid 090100Z - 091200Z

    ...NO SEVERE THUNDERSTORM AREAS FORECAST...

    ...SUMMARY...
    Severe thunderstorms are not expected through tonight.

    ...Discussion...
    The Marginal Risk across western/central Kansas was removed with
    this outlook update. A cluster of thunderstorm activity continues to
    shift south and east, but has largely remained below severe limits.
    This activity is expected to further weaken over the next couple of
    hours with the loss of daytime heating and gradually waning MLCAPE.

    ..Thornton.. 04/09/2026

    $$

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  • From COD Weather Processor@1:2320/107 to wx-storm@lists.illinois.edu on Thursday, April 09, 2026 05:59:44
    ACUS01 KWNS 090559
    SWODY1
    SPC AC 090557

    Day 1 Convective Outlook
    NWS Storm Prediction Center Norman OK
    1257 AM CDT Thu Apr 09 2026

    Valid 091200Z - 101200Z

    ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS CENTRAL/NORTHEAST
    KANSAS INTO SOUTHEAST NEBRASKA AND NORTHWEST MISSOURI...

    ...SUMMARY...
    Areas of hail and strong wind gusts are expected this afternoon and
    evening in parts of the lower to mid Missouri Valley westward into
    Kansas. Locally very large hail is possible.

    ...Synopsis...
    The upper-level pattern across the US today will consist of a
    deepening trough across the Western US with enhanced westerly flow
    extending across the central/northern US within the base of a
    broader upper-low across portions of Canada. Within the broad area
    of westerly flow, several disturbances will rotate across the
    northern Plains into the Great Lakes Region.

    At the surface, a warm front will lift northward through the day
    across the central Plains, extending as far north as southern NE/IA.
    As a surface high builds to the north across the Dakotas, this
    boundary will sag southward as a cold front through the late
    afternoon/evening. Scattered thunderstorm development is expected
    along this east/west oriented boundary and as well across the
    dryline further west into the OK/TX Panhandles. The primary threat
    will be for large to very large hail and damaging wind. A more
    isolated risk for large hail will extend southward across the
    dryline into western Kansas/OK/TX Panhandles.

    ...Central Plains...
    South of the aforementioned boundary across central KS into
    southeastern NE, low to mid-50s dew points in combination with
    strong daytime heating will yield moderate MLCAPE values around
    1000-1500 J/kg. Thunderstorm activity should develop along the warm
    front around 18z and increase with the incoming upper-level wave and
    cooling aloft. Forecast soundings along and south of the boundary in
    Kansas depict steep low to mid-level lapse rates (7-8 C/km) and deep
    layer shear around 40 kts, supportive of supercells capable of large
    to very large hail(some 2+ inches in diameter)and severe wind. The
    Slight was extended southward into central Kansas to account for
    potential for development into this region and continuation of the
    large to very large hail threat.

    With west to northwest winds aloft, all these storms may eventually
    merge into the evening, propagating southeastward across much of
    eastern KS into northwest MO. The warm boundary layer, combined with
    cold downdraft material, will likely support scattered damaging
    gusts.

    ...Northern California/Oregon Coasts...
    As the upper-level low approaches the West Coast, forcing for ascent
    will overspread portions of northern California into southern Oregon
    with scattered thunderstorm development expected by the late
    morning/afternoon. Sufficient moisture and MLCAPE will extend inland overlapping deep layer shear 20-25 kts and steep low to mid-level
    lapse rates to support potential for strong to severe wind gusts. As
    such, a 5% wind area was introduced with this outlook to cover this
    potential. Some instances of small hail will also be possible, owing
    to steep lapse rates and cooling temperatures aloft.

    ..Thornton/Chalmers.. 04/09/2026

    $$

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  • From COD Weather Processor@1:2320/107 to wx-storm@lists.illinois.edu on Thursday, April 09, 2026 12:52:14
    ACUS01 KWNS 091252
    SWODY1
    SPC AC 091250

    Day 1 Convective Outlook
    NWS Storm Prediction Center Norman OK
    0750 AM CDT Thu Apr 09 2026

    Valid 091300Z - 101200Z

    ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS THE CENTRAL
    PLAINS AND LOWER/MIDDLE MISSOURI VALLEY...

    ...SUMMARY...
    Severe storms capable of large hail and severe wind gusts are
    expected late this afternoon and evening across Kansas, southeast
    Nebraska into northwest Missouri and southwest Iowa. Isolated severe
    storms may also occur across the south-central High Plains and
    northern California/western Oregon.

    ...Central Plains and Lower/Middle Missouri Valley...
    A frontal zone will focus and shift northward toward across Kansas
    toward the Kansas/Nebraska and Iowa/Missouri border vicinities
    today, before gradually accelerating southeastward tonight. The
    region will be influenced later today by a secondary shortwave
    trough digging southeastward over the northern Plains, with the
    persistence of cyclonic and somewhat strengthening mid/upper-level
    flow. On the nose of south-southwesterly lower tropospheric winds,
    low-level moisture will diurnally increase along/south of the front,
    offset by ample mixing across Kansas, resulting in surface dewpoints
    mainly in the lower/middle 50s F into peak heating. Beneath very
    steep mid-level lapse rates, 1000-1500 J/kg MLCAPE values are
    expected near/south of the front.

    After some early day thunderstorms, more intense surface-based
    thunderstorm development should occur as early as 22-23z/5-6pm CDT
    near the boundary including portions of northern Kansas/southeast
    Nebraska to the Iowa/Missouri border region, with other more
    isolated and higher-based storms possible across western Kansas and
    the nearby High Plains in vicinity of the lee trough/surface low.

    Moderately strong westerlies will reside along/north of the
    boundary, with 40+ kt effective shear supporting supercells capable
    of large hail, potentially some in excess of 2 inches in diameter.
    Some tornado potential may exist mainly across northeast Kansas/far
    southeast Nebraska and northwest Missouri near the boundary, but
    this overall potential will tend to be mitigated by modest-caliber
    moisture and the influence of diurnal mixing. Severe winds are also
    possible into evening as storms tend to cluster and spread/increase east-southeastward during the evening, although the modest early
    season moisture and nocturnal influences will lead to a diminished
    intensity trend into late evening.

    ...Northern California/western Oregon...
    As the upper-level low approaches the West Coast, forcing for ascent
    will overspread portions of northern California into southern Oregon
    with scattered thunderstorm development expected into afternoon.
    Sufficient moisture and CAPE will exist inland beneath strengthening
    deep-layer southwesterly winds ahead of the trough. As lapse rates
    steepen and flow aloft increases, storms may be capable of strong to
    severe wind gusts and possibly some hail.

    ..Guyer/Weinman.. 04/09/2026

    $$

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  • From COD Weather Processor@1:2320/107 to wx-storm@lists.illinois.edu on Thursday, April 09, 2026 16:30:46
    ACUS01 KWNS 091630
    SWODY1
    SPC AC 091628

    Day 1 Convective Outlook
    NWS Storm Prediction Center Norman OK
    1128 AM CDT Thu Apr 09 2026

    Valid 091630Z - 101200Z

    ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF
    KANSAS INTO SOUTHEAST NEBRASKA AND NORTHWEST MISSOURI...

    ...SUMMARY...
    Severe thunderstorms capable of producing large hail and severe wind
    gusts are expected late this afternoon and evening across parts of
    Kansas, southeast Nebraska, and northwest Missouri. Isolated severe thunderstorms may also occur across portions of the south-central
    High Plains and northern California/southwest Oregon.

    ...Southern High Plains into the Central Plains and Lower/Mid
    Missouri Valley...
    Ongoing precipitation/thunderstorms and related cloud cover across north-central/northeast KS into southeast NE/southwest IA is being
    aided by modest low-level warm/moist advection in the vicinity of a
    surface front. Current expectations are for this activity to
    gradually diminish in coverage as it shifts eastward into the
    northwest MO/southern IA. In its wake, daytime heating may be
    hampered a bit by residual cloudiness across much of
    north-central/northeast KS. Even so, continued northward low-level
    moisture advection is anticipated across the southern/central Plains
    through the afternoon, with surface dewpoints generally in the upper
    40s to low/mid 50s. This, coupled with steep mid-level lapse rates
    and cold temperatures aloft, will aid in the development of moderate instability (MLCAPE around 1000-1500 J/kg) along/south of a front
    draped generally west to east across northern KS/MO.

    Stronger ascent aloft and enhanced westerly flow at mid/upper levels
    will remain mostly displaced to the north of the central Plains
    today, as multiple mid-level perturbations rotate through mean
    mid/upper-level troughing over central/eastern Canada. Still, most
    guidance continues to suggest that minimal MLCIN will exist in the
    vicinity of the front in north-central/northeast KS and southeast NE
    by 22-23Z as surface temperatures warm into the 70s/low 80s.
    Isolated to scattered thunderstorms are expected to develop across
    this area by late afternoon/early evening, with modest
    south-southwesterly low-level winds veering to west-northwesterly at
    mid/upper levels supporting 35-45 kt of deep-layer shear.

    Initial convective development will likely be supercellular and pose
    a threat for mainly large hail (isolated 2+ inches in diameter
    possible). Fairly large surface temperature-dewpoint spreads with a
    well-mixed boundary layer and related high cloud bases render
    considerable uncertainty regarding tornado potential. But, some risk
    for a tornado or two may focus along/near the front through early
    evening as effective SRH gradually increases in tandem with a
    strengthening south-southwesterly low-level jet. Otherwise, the risk
    for severe/damaging winds may gradually increase through mid evening
    as thunderstorms tend to cluster/grow modestly upscale. But, the
    severe wind risk will likely become more limited by late evening
    with the loss of daytime heating and increasing MLCIN with
    southward/eastward extent.

    Isolated thunderstorms may also develop this afternoon farther
    southwest across the central/southern High Plains along and east of
    a sharpening surface dryline/lee trough. Overall convective coverage
    remains highly uncertain given nebulous/weak large-scale ascent this
    far south. Still, some risk for occasional hail and severe gusts
    should exist with any sustained cells or clusters that can develop
    and spread east-southeastward through the late afternoon/early
    evening.

    ...Northern California/Southwest Oregon...
    As an upper-level low over the eastern Pacific approaches the West
    Coast today, large-scale ascent will overspread portions of northern
    CA into southern OR with scattered thunderstorm development expected
    into afternoon. Sufficient moisture and instability should exist
    inland beneath strengthening deep-layer southwesterly winds ahead of
    the trough to support semi-organized convection. As low-level lapse
    rates gradually steepen and flow aloft increases, this activity may
    be capable of producing isolated strong to severe gusts and possibly
    some hail.

    ..Gleason/Wendt.. 04/09/2026

    $$

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  • From COD Weather Processor@1:2320/107 to wx-storm@lists.illinois.edu on Thursday, April 09, 2026 19:45:45
    ACUS01 KWNS 091945
    SWODY1
    SPC AC 091943

    Day 1 Convective Outlook
    NWS Storm Prediction Center Norman OK
    0243 PM CDT Thu Apr 09 2026

    Valid 092000Z - 101200Z

    ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS PORTIONS OF
    CENTRAL AND NORTHEAST KANSAS INTO SOUTHERN NEBRASKA AND FAR
    NORTHWEST MISSOURI...

    ...SUMMARY...
    Severe thunderstorms capable of producing large hail and severe wind
    gusts are expected late this afternoon and evening across parts of
    Kansas, southeast Nebraska, and northwest Missouri. Isolated severe thunderstorms may also occur across portions of the south-central
    High Plains and northern California/southwest Oregon.

    ...20z Update central and southern Plains...
    Thunderstorm development remains likely late this afternoon and this
    evening along the frontal zone from southern NE into northeast KS.
    While remnant cloud cover has slowed destabilization, sufficient
    buoyancy and supercell wind profiles will likely support a risk for
    hail, damaging gusts and perhaps a tornado or two this
    afternoon/evening. See MCD #367 for specific short-term information.

    Farther south along the trailing surface trough/dryline, more
    isolated thunderstorm development is expected across the TX
    Panhandle and far eastern NM. High cloud bases with deep inverted-v
    structures could support isolated severe wind gusts with the heavier
    cores. Storm coverage is likely to decrease farther south where
    weaker forcing and overall more limited buoyancy is present. Still,
    isolated storms are possible, and the 5% wind area was expanded
    southward slightly for the latest hi-res guidance.

    ...CA and OR...
    East of an upper low, broad-scale ascent over a modestly warm/moist
    air mass was supporting widely scattered thunderstorms over portions
    of northern CA and southern OR. While overall buoyancy is weak
    (generally below 500 J/kg of MLCAPE), strengthening southerly flow
    aloft could support a few organized clusters or transient supercells
    capable of producing isolated strong to severe gusts and some hail.

    ..Lyons.. 04/09/2026

    .PREV DISCUSSION... /ISSUED 1128 AM CDT Thu Apr 09 2026/

    ...Southern High Plains into the Central Plains and Lower/Mid
    Missouri Valley...
    Ongoing precipitation/thunderstorms and related cloud cover across north-central/northeast KS into southeast NE/southwest IA is being
    aided by modest low-level warm/moist advection in the vicinity of a
    surface front. Current expectations are for this activity to
    gradually diminish in coverage as it shifts eastward into the
    northwest MO/southern IA. In its wake, daytime heating may be
    hampered a bit by residual cloudiness across much of
    north-central/northeast KS. Even so, continued northward low-level
    moisture advection is anticipated across the southern/central Plains
    through the afternoon, with surface dewpoints generally in the upper
    40s to low/mid 50s. This, coupled with steep mid-level lapse rates
    and cold temperatures aloft, will aid in the development of moderate instability (MLCAPE around 1000-1500 J/kg) along/south of a front
    draped generally west to east across northern KS/MO.

    Stronger ascent aloft and enhanced westerly flow at mid/upper levels
    will remain mostly displaced to the north of the central Plains
    today, as multiple mid-level perturbations rotate through mean
    mid/upper-level troughing over central/eastern Canada. Still, most
    guidance continues to suggest that minimal MLCIN will exist in the
    vicinity of the front in north-central/northeast KS and southeast NE
    by 22-23Z as surface temperatures warm into the 70s/low 80s.
    Isolated to scattered thunderstorms are expected to develop across
    this area by late afternoon/early evening, with modest
    south-southwesterly low-level winds veering to west-northwesterly at
    mid/upper levels supporting 35-45 kt of deep-layer shear.

    Initial convective development will likely be supercellular and pose
    a threat for mainly large hail (isolated 2+ inches in diameter
    possible). Fairly large surface temperature-dewpoint spreads with a
    well-mixed boundary layer and related high cloud bases render
    considerable uncertainty regarding tornado potential. But, some risk
    for a tornado or two may focus along/near the front through early
    evening as effective SRH gradually increases in tandem with a
    strengthening south-southwesterly low-level jet. Otherwise, the risk
    for severe/damaging winds may gradually increase through mid evening
    as thunderstorms tend to cluster/grow modestly upscale. But, the
    severe wind risk will likely become more limited by late evening
    with the loss of daytime heating and increasing MLCIN with
    southward/eastward extent.

    Isolated thunderstorms may also develop this afternoon farther
    southwest across the central/southern High Plains along and east of
    a sharpening surface dryline/lee trough. Overall convective coverage
    remains highly uncertain given nebulous/weak large-scale ascent this
    far south. Still, some risk for occasional hail and severe gusts
    should exist with any sustained cells or clusters that can develop
    and spread east-southeastward through the late afternoon/early
    evening.

    ...Northern California/Southwest Oregon...
    As an upper-level low over the eastern Pacific approaches the West
    Coast today, large-scale ascent will overspread portions of northern
    CA into southern OR with scattered thunderstorm development expected
    into afternoon. Sufficient moisture and instability should exist
    inland beneath strengthening deep-layer southwesterly winds ahead of
    the trough to support semi-organized convection. As low-level lapse
    rates gradually steepen and flow aloft increases, this activity may
    be capable of producing isolated strong to severe gusts and possibly
    some hail.

    $$

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  • From COD Weather Processor@1:2320/107 to wx-storm@lists.illinois.edu on Friday, April 10, 2026 01:02:50
    ACUS01 KWNS 100102
    SWODY1
    SPC AC 100100

    Day 1 Convective Outlook
    NWS Storm Prediction Center Norman OK
    0800 PM CDT Thu Apr 09 2026

    Valid 100100Z - 101200Z

    ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FOR PARTS OF CENTRAL/NORTHEAST KS INTO FAR SOUTHEAST NE/NORTHWEST MO...

    ...SUMMARY...
    Severe thunderstorms capable of producing large hail and severe wind
    gusts remain possible this evening across parts of Kansas, southeast
    Nebraska, and northwest Missouri.

    ...Central/southern Plains...
    Scattered strong to severe storms have developed this evening from
    southwest into north-central KS and far southern NE this evening,
    near/south of a southward-moving cold front, and along/east of a
    weak dryline. Despite modest low-level moisture (with warm-sector
    dewpoints generally in the low 50s F), steep midlevel lapse rates
    and relatively cold temperatures aloft are supporting MLCAPE of
    1000-1500 J/kg, within a moderately sheared environment.

    A few relatively high-based supercells remain possible through the
    evening, with an attendant threat of large hail (potentially
    golf-ball-sized or larger) and localized severe gusts. A tornado
    also cannot be ruled out across north-central/northeast KS, as
    low-level moisture/shear gradually improve in conjunction with a
    nocturnal low-level jet. Otherwise, some upscale growth remains
    possible with time, which could result in at least an isolated
    severe-wind threat spreading across parts of northeast KS and
    northwest MO later tonight, before the threat diminishes in response
    to increasing MLCINH. See MCD 370 and MD 371 for more information
    regarding the short-term severe threat in this area.

    ...Northwest CA/southwest OR vicinity...
    A few strong storms remain possible through early evening across
    parts of northwest CA and southwest OR, in association with an upper
    low off of the northern CA coast. Any remaining severe threat should
    tend to diminish with time, as already weak buoyancy further
    decreases due to convective overturning and nocturnal stabilization.

    ...CA Central Valley...
    Isolated strong storms have recently developed across parts of the
    CA central valley, with a supercell noted northwest of Fresno. While
    deep-layer flow is rather weak, MUCAPE of 500-1000 J/kg and modest
    veering of the wind profile could support a very isolated threat of
    gusty winds and small to marginally severe hail, though coverage and
    duration of the threat are expected to remain limited.

    ..Dean.. 04/10/2026

    $$

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  • From COD Weather Processor@1:2320/107 to wx-storm@lists.illinois.edu on Friday, April 10, 2026 05:55:21
    ACUS01 KWNS 100555
    SWODY1
    SPC AC 100553

    Day 1 Convective Outlook
    NWS Storm Prediction Center Norman OK
    1253 AM CDT Fri Apr 10 2026

    Valid 101200Z - 111200Z

    ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS FOR PARTS OF THE SOUTH-CENTRAL PLAINS INTO THE OZARKS...NORTHERN NV INTO SOUTHEAST
    OR/SOUTHWEST ID...AND PARTS OF CENTRAL CA...

    ...SUMMARY...
    Thunderstorms with isolated large hail and severe gusts will be
    possible this afternoon and evening from parts of the south-central
    Plains into the Ozarks. Strong to locally severe storms may also
    occur from northern Nevada into southeast Oregon and southwest
    Idaho, and also across parts of central California.

    ...Synopsis...
    A mid/upper-level shortwave trough will move from the Great Lakes
    region toward New England through the period. Upstream, a mid/upper
    low initially offshore of California will move inland toward the
    Great Basin as a shortwave trough, as another mid/upper
    shortwave/low approaches the Pacific Coast.

    ...Parts of the south-central Plains into the Ozarks...
    In the wake of morning elevated convection, an outflow-reinforced
    cold front is expected to become nearly stationary this afternoon
    and early evening. Steep midlevel lapse rates and rather cool
    temperatures aloft will support MLCAPE of near/above 1500 J/kg
    along/south of the front, with minimal MLCINH by afternoon.
    Scattered thunderstorms are expected to develop by late afternoon in
    the vicinity of the boundary across parts of southern KS/northern OK
    into the Ozarks, with additional development possible near the front
    and within a post-frontal regime across the south-central High
    Plains vicinity.

    With rather modest large-scale ascent and weak deep-layer flow
    forecast across the region, storm organization and duration may
    generally remain somewhat limited. However, more organized cells may
    briefly develop on an isolated basis near the boundary, where some
    enhancement to effective shear/SRH will be possible. Isolated large
    hail appears to be the most likely hazard, though localized
    strong/damaging gusts also cannot be ruled out with the strongest
    storms.

    ...Northern NV into southeast OR/southwest ID and central/northern
    CA...
    In response to the approaching mid/upper low and shortwave trough,
    scattered thunderstorm development is expected this afternoon across
    parts of central/northern CA into the northern Great Basin and
    interior Northwest. Cold temperatures aloft and rather strong
    diurnal heating will result in steep low/midlevel lapse rates and
    MUCAPE increasing to near/above 500 J/kg, despite limited low-level
    moisture.

    Midlevel flow and deep-layer shear will gradually increase with
    time, with the most favorable overlap of shear and instability
    currently expected from northern NV into southeast OR/southwest ID.
    Modestly organized cells/clusters and perhaps a couple of supercells
    may develop in this area, with an attendant threat of hail and
    localized severe gusts.

    A few strong storms may also develop across parts of the Sacramento
    and northern San Joaquin Valleys in California. While deep-layer
    shear will be somewhat less favorable compared to the northern Great
    Basin area, cold temperatures aloft (near/below -20C at 500 mb) may
    support potential for marginally severe hail with the strongest
    storms. Local terrain influences could also support transient cell organization/rotation and possibly a brief tornado, though this
    potential remains very uncertain at this time.

    ..Dean/Chalmers.. 04/10/2026

    $$

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  • From COD Weather Processor@1:2320/107 to wx-storm@lists.illinois.edu on Friday, April 10, 2026 12:37:52
    ACUS01 KWNS 101237
    SWODY1
    SPC AC 101236

    Day 1 Convective Outlook
    NWS Storm Prediction Center Norman OK
    0736 AM CDT Fri Apr 10 2026

    Valid 101300Z - 111200Z

    ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF
    THE SOUTH-CENTRAL PLAINS/OZARKS AND NORTHERN CALIFORNIA/GREAT
    BASIN...

    ...SUMMARY...
    Thunderstorms with isolated large hail and severe gusts are possible
    this afternoon and evening across parts of the south-central Plains
    to the Ozarks. Strong to locally severe storms may also occur from western/northern Nevada into southeast Oregon and southwest Idaho,
    and also across parts of north-central California.

    ...South-central Plains/Ozarks...
    Scattered rain and generally weak thunderstorms will continue to
    accompany and reinforce a southward-shifting front, with the
    boundary stalling today, before starting to shift back northward
    late tonight. Weakening flow aloft will occur today in the presence
    of a building upper ridge and corresponding height rises. As
    outflows dissipate, ample heating/mixing is expected later today to
    the south of the front, where MLCAPE values may exceed 1500 J/kg
    across Oklahoma/Texas Panhandle and northeast New Mexico.

    Even with modest overall forcing for ascent, scattered thunderstorms
    are expected to develop by late afternoon in the vicinity of the
    boundary across parts of far southern Kansas/northern Oklahoma into
    the Ozarks, with additional development possible near the front, and
    also within a post-frontal regime across the south-central High
    Plains vicinity.

    With rather modest large-scale ascent and weak deep-layer flow
    across the region, storm organization and duration may generally
    remain somewhat limited. However, more organized cells may briefly
    develop on an isolated basis more immediately near the boundary,
    where some enhancement to effective shear/SRH will be possible.
    Isolated large hail appears to be the most likely hazard, although
    localized strong/damaging wind gusts could also occur.

    ...Nevada/southeast OR/southwest ID and north-central CA...
    A closed upper low off the coast of northern California will open
    and become more progressive, reaching the Sierra and parts of the
    Great Basin tonight. Related forcing for ascent and moisture will
    influence scattered thunderstorm development this afternoon across
    parts of central/northern California into the northern Great Basin
    and interior Northwest. Cold temperatures aloft and rather strong
    diurnal heating will result in steep low/mid-level lapse rates and
    MUCAPE increasing to near/above 500 J/kg.

    Mid-level flow and deep-layer shear will gradually increase over
    time, with the most favorable overlap of vertical shear and
    instability expected across western/northern Nevada into southeast
    Oregon and southwest Idaho. Semi-organized cells/clusters, and
    perhaps even a few supercells, may develop with an attendant threat
    of hail and localized severe wind gusts.

    A few locally severe storms may also develop across parts of the
    Sacramento and northern San Joaquin Valleys in California this
    afternoon. While deep-layer shear will be somewhat weaker as
    compared to the northern Great Basin, cold temperatures aloft
    (near/below -20C at 500 mb) may support marginally severe hail with
    the strongest storms. The steep lapse rate environment and local
    terrain influences could also support transient cell rotation and
    possibly funnels, or even a brief tornado, although this potential
    currently seems low/uncertain.

    ..Guyer/Broyles.. 04/10/2026

    $$

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  • From COD Weather Processor@1:2320/107 to wx-storm@lists.illinois.edu on Friday, April 10, 2026 16:31:52
    ACUS01 KWNS 101631
    SWODY1
    SPC AC 101630

    Day 1 Convective Outlook
    NWS Storm Prediction Center Norman OK
    1130 AM CDT Fri Apr 10 2026

    Valid 101630Z - 111200Z

    ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF
    THE SOUTH-CENTRAL PLAINS/OZARKS...NORTHERN CALIFORNIA/GREAT
    BASIN...AND WESTERN OREGON...

    ...SUMMARY...
    Thunderstorms with isolated large hail and severe gusts are possible
    this afternoon and evening across parts of the south-central Plains
    to the Ozarks. Strong to locally severe storms may also occur from western/northern Nevada into southeast Oregon and southwest Idaho,
    and also across parts of north-central California.

    ...Southern High Plains/South-central Plains into the Ozarks...
    Recent surface analysis places a low over the western TX Panhandle,
    with a cold front extending east-northeastward from this low across
    northwest and north-central OK, and far southeast KS, before
    becoming oriented more northeastward across southern and central MO.
    Showers and thunderstorms are ongoing in the vicinity of this
    boundary, as well modest southeastward-progressing outflow, across
    far southern KS and northern OK.

    The cold front is forecast to trend more stationary throughout the
    day as heights rise across the Plains and southerly low-level flow
    persists across the southern Plains, with the outflow following this
    trend as well. After 06Z, this stationary boundary will likely begin
    shifting back northward into southern KS as warm front. Additional
    thunderstorm development is possible amid low-level convergence near
    both the stationary front and outflow as the airmass modestly
    destabilizes this afternoon. Isolated damaging gusts and/or
    marginally severe hail is possible with the strongest storms, but
    modest shear and buoyancy suggests most storms will be sub-severe.

    Farther west, low-level convergence along a sharpening lee trough
    may contribute to late afternoon thunderstorm development across the
    southern High Plain, particularly northeast NM. High cloud bases and
    steep low-level lapse rates support the potential for strong
    downbursts with any deep/more persistent updrafts. Some interaction
    with the western extent of the frontal zone is possible as well,
    which could briefly enhance updrafts, contributing to a continued
    potential for damaging gusts as well as isolated hail.

    ...North-central CA/western OR into the northern Great Basin...
    Upper low currently centered just off the northern/central CA coast
    is forecast to become more progressive and negatively tilted
    throughout the day today. Mid-level moisture and ascent attendant to
    this wave will support scattered thunderstorm development this
    afternoon from central/northern CA and western OR into the northern
    Great Basin and interior Northwest. Cold temperatures aloft (i.e.
    -20 deg C at 500 mb) and strong diurnal heating will result in steep low/mid-level lapse rates and at least modest buoyancy across much
    of the region.

    A few areas (interior valley of central CA, Willamette Valley in OR,
    and northern NV/southwest OR/southern ID) appear to have a slightly
    higher potential for isolated strong to severe storms, largely a
    result of more diurnal heating/higher afternoon temperatures.
    Greater buoyancy combined with moderate/strong deep-layer shear will
    support semi-organized cells/clusters, and perhaps even a few
    supercells, may develop with an attendant threat of hail and
    localized severe wind gusts. Deep-layer shear will be a bit weaker
    across the interior valley of central CA but still sufficient for a
    few organized storms. The steep lapse rate environment and local
    terrain influences could also support transient cell rotation and
    possibly funnels, or even a brief tornado.

    ..Mosier/Squitieri.. 04/10/2026

    $$

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  • From COD Weather Processor@1:2320/107 to wx-storm@lists.illinois.edu on Friday, April 10, 2026 19:53:53
    ACUS01 KWNS 101953
    SWODY1
    SPC AC 101952

    Day 1 Convective Outlook
    NWS Storm Prediction Center Norman OK
    0252 PM CDT Fri Apr 10 2026

    Valid 102000Z - 111200Z

    ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS OVER PARTS OF
    OREGON...THE CENTRAL VALLEY OF CALIFORNIA...THE GREAT BASIN AND
    SOUTHERN PLAINS/OZARKS...

    ...SUMMARY...
    Thunderstorms with isolated large hail and severe gusts remain
    possible this afternoon and evening across parts of the
    south-central Plains to the Ozarks. Strong to locally severe storms
    may also occur from western/northern Nevada into southeast Oregon
    and southwest Idaho, and also across parts of north-central
    California.

    ...20z Update...
    Minimal changes were made to the prior outlook. A prominent
    differential heating/outflow boundary associated with a cluster of thunderstorms over OK is forecast to continue sagging southward this
    afternoon. An increase in storm coverage is possible this afternoon
    and evening associated with the ongoing cluster and the trailing
    boundary. With moderate buoyancy weak vertical shear, a low-end risk
    for damaging gusts and hail could develop. 5% wind and hail
    probabilities have been expanded slightly farther southeastward.

    To the West across the Great Basin, strong mid-level ascent ahead of
    the upper low over the Pacific Coast was overspreading a marginally
    moist and buoyant air mass across parts of NV. Strong southerly flow
    aloft could support a few semi-organized storms or clusters capable
    of damaging gusts and sporadic hail. 5% wind and hail probabilities
    have been expanded southward over parts of NV where buoyancy and
    shear overlap could support some severe potential.

    Otherwise, isolated severe storms remain possible across parts of
    the central Valley of CA and western OR. The forecast remains
    unchanged, see the prior discussion for more information.

    ..Lyons.. 04/10/2026

    .PREV DISCUSSION... /ISSUED 1130 AM CDT Fri Apr 10 2026/

    ...Southern High Plains/South-central Plains into the Ozarks...
    Recent surface analysis places a low over the western TX Panhandle,
    with a cold front extending east-northeastward from this low across
    northwest and north-central OK, and far southeast KS, before
    becoming oriented more northeastward across southern and central MO.
    Showers and thunderstorms are ongoing in the vicinity of this
    boundary, as well modest southeastward-progressing outflow, across
    far southern KS and northern OK.

    The cold front is forecast to trend more stationary throughout the
    day as heights rise across the Plains and southerly low-level flow
    persists across the southern Plains, with the outflow following this
    trend as well. After 06Z, this stationary boundary will likely begin
    shifting back northward into southern KS as warm front. Additional
    thunderstorm development is possible amid low-level convergence near
    both the stationary front and outflow as the airmass modestly
    destabilizes this afternoon. Isolated damaging gusts and/or
    marginally severe hail is possible with the strongest storms, but
    modest shear and buoyancy suggests most storms will be sub-severe.

    Farther west, low-level convergence along a sharpening lee trough
    may contribute to late afternoon thunderstorm development across the
    southern High Plain, particularly northeast NM. High cloud bases and
    steep low-level lapse rates support the potential for strong
    downbursts with any deep/more persistent updrafts. Some interaction
    with the western extent of the frontal zone is possible as well,
    which could briefly enhance updrafts, contributing to a continued
    potential for damaging gusts as well as isolated hail.

    ...North-central CA/western OR into the northern Great Basin...
    Upper low currently centered just off the northern/central CA coast
    is forecast to become more progressive and negatively tilted
    throughout the day today. Mid-level moisture and ascent attendant to
    this wave will support scattered thunderstorm development this
    afternoon from central/northern CA and western OR into the northern
    Great Basin and interior Northwest. Cold temperatures aloft (i.e.
    -20 deg C at 500 mb) and strong diurnal heating will result in steep low/mid-level lapse rates and at least modest buoyancy across much
    of the region.

    A few areas (interior valley of central CA, Willamette Valley in OR,
    and northern NV/southwest OR/southern ID) appear to have a slightly
    higher potential for isolated strong to severe storms, largely a
    result of more diurnal heating/higher afternoon temperatures.
    Greater buoyancy combined with moderate/strong deep-layer shear will
    support semi-organized cells/clusters, and perhaps even a few
    supercells, may develop with an attendant threat of hail and
    localized severe wind gusts. Deep-layer shear will be a bit weaker
    across the interior valley of central CA but still sufficient for a
    few organized storms. The steep lapse rate environment and local
    terrain influences could also support transient cell rotation and
    possibly funnels, or even a brief tornado.

    $$

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  • From COD Weather Processor@1:2320/107 to wx-storm@lists.illinois.edu on Saturday, April 11, 2026 00:59:55
    ACUS01 KWNS 110059
    SWODY1
    SPC AC 110058

    Day 1 Convective Outlook
    NWS Storm Prediction Center Norman OK
    0758 PM CDT Fri Apr 10 2026

    Valid 110100Z - 111200Z

    ...NO SEVERE THUNDERSTORM AREAS FORECAST...

    ...SUMMARY...
    Isolated to scattered thunderstorms remain possible during the late
    evening hours across parts of the southern Plains and Great Basin;
    however, the overall severe risk appears limited.

    ...Southern Plains...
    Latest MRMS imagery depicts steady weakening of convection across
    northeast NM and across northern OK with the onset of nocturnal
    cooling and expanding convective outflows. While a couple of
    stronger storms are noted across far eastern NM and southwest TX,
    weak deep-layer wind shear and diminishing buoyancy should favor a
    weakening trend heading into the late evening hours.

    Additional elevated thunderstorms are anticipated well north of the
    stalled surface boundary along the OK/KS border with recent CAM
    guidance suggesting multi-cell clusters developing across portions
    of central to northeast KS after 03 UTC. The recent 00z DDC RAOB
    likely sampled the environment this convection will develop in, and
    hints that at least a small hail threat may materialize with
    initially discrete cells prior to upscale growth within the first
    couple of hours after initiation.

    ...Great Basin...
    Similar to the southern Plains, convective trends have largely shown
    signs of weakening over the past hour across central to northern NV
    where surface temperatures are quickly cooling into the 60s. The
    combination of rain-cooled air/outflows and the onset of nocturnal
    cooling should further reduce any remaining mixed-layer buoyancy
    (which was already fairly marginal per regional 00z RAOBs).
    Consequently, the thermodynamic environment no longer appears
    supportive of intense convection, though a strong storm or two may
    persist for the next hour as the boundary layer continues to
    stabilize.

    ..Moore.. 04/11/2026

    $$

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  • From COD Weather Processor@1:2320/107 to wx-storm@lists.illinois.edu on Saturday, April 11, 2026 05:43:26
    ACUS01 KWNS 110543
    SWODY1
    SPC AC 110542

    Day 1 Convective Outlook
    NWS Storm Prediction Center Norman OK
    1242 AM CDT Sat Apr 11 2026

    Valid 111200Z - 121200Z

    ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PORTIONS OF
    THE SOUTHERN HIGH PLAINS...

    ...SUMMARY...
    Scattered thunderstorms producing hail and strong wind gusts will be
    possible across portions of the southern High Plains this afternoon
    and evening. More isolated strong to severe thunderstorms are
    expected across parts of the central Rockies, central Plains, upper
    Mississippi Valley, and portions of the California coast.

    ...Synopsis...
    An upper trough is evident in early-morning water-vapor imagery off
    the California Coast. This wave will gradually de-amplify over the
    next 24 hours as it progresses northeastward into the northern
    Rockies. Further south, a lower-amplitude upper disturbance is noted
    off the coast of Baja CA, and will migrate northeast into southwest
    TX through this evening. Ahead of these features, modest lee
    troughing along the High Plains and the southeastward shift of
    surface high from the Midwest into the upper OH Valley will yield an
    extended fetch of southerly low-level flow from the TX coast into
    the upper MS Valley, resulting in northward moisture return as well
    as a broad zone of isentropic ascent from the Plains into the upper
    MS Valley.

    ...Southern High Plains...
    Thunderstorm development appears likely by mid-afternoon across
    southwest TX as ascent associated with the upper disturbance off the
    coast of Baja CA migrates out of northern Mexico and overspreads
    returning moisture. Initially discrete cells are likely and will
    pose a threat for large hail given adequate deep-layer wind shear.
    However, weak capping and strong ascent should promote upscale
    growth by early evening into one or more convective lines. As this
    transition occurs, strong to severe wind gusts will become the
    predominant hazard, though an embedded circulation or two may be
    possible. Based on latest guidance, the wind/tornado threat may be
    maximized along and south of the I-20 corridor where the signal for clustering/banding is greatest in latest CAM and ensemble guidance.

    ...Central Plains to the Upper MS Valley...
    Low-level warm air advection will likely become increasingly focused
    through the day and into the overnight hours from the central Plains
    into the upper MS Valley. 850 mb winds are forecast to strengthen to
    40-50 knots by this evening and will support steady moistening in
    the lowest 1-2 km under a plume of 7-7.5 C/km mid-level lapse rates.
    Forecast soundings suggest that this environment will be weakly
    capped and should support isolated to scattered thunderstorms during
    the afternoon hours across the central Plains before
    spreading/re-developing northeastward into the upper MS Valley late
    tonight. While deep-layer wind shear will not be overly strong
    (around 30 knots), it should be sufficient for a few transient
    organized cells capable of large hail.

    A more conditional supercell threat may materialize across portions
    of the lower MO valley where some CAM guidance depicts convection
    developing late afternoon along the surface warm front. Forecast
    soundings from this region suggest a weakly capped, but moderately
    buoyant and strongly sheared environment may be in place that could
    support a well-organized supercell. However, poor ensemble consensus
    limits confidence in this scenario.

    ...Central to northern Rockies...
    00z RAOBs from the Great Basin/Four Corners region sampled steep
    mid-level lapse rates with modest mid-level moisture. While fairly
    dry, this environment was sufficient for convection yesterday and
    will likely support additional thunderstorms across the central to
    northern Rockies this afternoon as diurnal heating erodes inhibition
    and maximizes surface-based buoyancy. Ascent ahead of the decaying
    upper wave will likely support isolated to scattered thunderstorms,
    and a combination of modest deep-layer wind shear and deep,
    well-mixed boundary layers will promote strong to severe downburst
    winds. A fairly strong wind signal in latest HREF guidance
    co-located with transient UH streaks lent enough confidence to
    expand 5% wind probabilities northwestward to address this concern.

    ...CA Coast...
    A progressive upper wave will move into northern CA late this
    afternoon into the overnight hours. As this occurs, ascent within
    the left-exit region of an attendant upper jet, coupled with cool
    mid-level temperatures near the center of the upper low, should
    support isolated thunderstorms across northern CA. Winds within the
    lowest 1-2 km should increase to around 40 knots as the wave moves
    onshore, which may be augmented by convective downdrafts to yield a
    few damaging gusts along the coast.

    ..Moore/Halbert.. 04/11/2026

    $$

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  • From COD Weather Processor@1:2320/107 to wx-storm@lists.illinois.edu on Saturday, April 11, 2026 12:44:29
    ACUS01 KWNS 111244
    SWODY1
    SPC AC 111242

    Day 1 Convective Outlook
    NWS Storm Prediction Center Norman OK
    0742 AM CDT Sat Apr 11 2026

    Valid 111300Z - 121200Z

    ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS THE
    SOUTHERN HIGH PLAINS...

    ...SUMMARY...
    Scattered thunderstorms producing hail and strong wind gusts are
    possible across portions of the southern High Plains this afternoon
    and evening. More isolated strong to severe thunderstorms are
    expected across parts of the central Rockies, central Plains, upper
    Mississippi Valley, and portions of the California coast.

    ...Southern High Plains...
    Thunderstorm development is likely by mid/late-afternoon across
    southwest Texas and eastern New Mexico as increase forcing for
    ascent overspreads modest but increasing low-level moisture.
    Initially discrete cells are likely and will pose a threat for large
    hail given adequate deep-layer wind shear /generally 30-40 kt/.
    However, weak capping and strong ascent should promote upscale
    growth by early evening into several linear clusters. As this
    transition occurs, strong to severe wind gust potential will
    increase and become the predominant hazard, though an embedded
    circulation or two may occur with a tornado possible.

    ...Central Plains to the Upper Mississippi Valley...
    Low-level warm air advection will likely become increasingly focused
    through the day and into the overnight hours from the central Plains
    into the upper Mississippi Valley. 850 mb winds are forecast to
    steadily strengthen to 40-60 kt by this evening and will support
    moistening in the lowest 1-2 km under a plume of 7-7.5 C/km
    mid-level lapse rates. Forecast soundings suggest that this
    environment will be weakly capped and should support isolated to
    widely scattered thunderstorms during the afternoon hours across the
    central Plains before spreading/re-developing northeastward into the
    upper Mississippi Valley late tonight. While deep-layer wind shear
    will not be overly strong (around 30 kt), it should be sufficient
    for a few organized cells capable of severe hail.

    A more conditional supercell potential may materialize by mid/late
    afternoon through early evening across portions of the middle/lower
    Missouri Valley near/just south of the northward-shifting surface
    warm front, which may augmented by residual cloud cover/weakening
    storms across northeast Kansas/far southeast Nebraska in the
    pre-dawn hours. Forecast soundings from this region suggest a weakly
    capped, but moderately buoyant airmass, with notably strong low-level/deep-layer wind profiles that would conditionally support
    supercells including some tornado risk.

    ...Central/northern Rockies...
    A northeast-ejecting shortwave trough, along with steep mid-level
    lapse rates and modest mid-level moisture, will likely support
    additional thunderstorms across the central to northern Rockies this
    afternoon as diurnal heating occurs. A combination of modest
    deep-layer wind shear and well-mixed boundary layers will support
    potential for strong to severe downburst winds.

    ...Northern/central California Coast...
    A progressive upper wave will continue eastward and reach the
    northern California coast tonight. As this occurs, ascent within
    the left-exit region of an attendant upper jet, coupled with cool
    mid-level temperatures near the center of the upper low, will
    support isolated thunderstorms across northern/central California.
    Winds within the lowest 1-2 km AGL should increase to around 40 kt
    as the wave moves onshore, which will contribute to the potential
    for convective downdrafts to produce a few locally damaging wind
    gusts.

    ..Guyer/Broyles.. 04/11/2026

    $$

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  • From COD Weather Processor@1:2320/107 to wx-storm@lists.illinois.edu on Saturday, April 11, 2026 16:30:00
    ACUS01 KWNS 111629
    SWODY1
    SPC AC 111628

    Day 1 Convective Outlook
    NWS Storm Prediction Center Norman OK
    1128 AM CDT Sat Apr 11 2026

    Valid 111300Z - 121200Z

    ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS THE
    SOUTHERN HIGH PLAINS...

    ...SUMMARY...
    Scattered thunderstorms producing hail and strong wind gusts are
    possible across portions of the southern High Plains this afternoon
    and evening. More isolated strong to severe thunderstorms are
    expected across parts of the central Rockies, central Plains, upper
    Mississippi Valley, and portions of the California coast.

    ...Synopsis...
    Recent satellite imagery reveals two shortwave troughs, one moving
    through the Great Basin and the other moving into central Mexico,
    progressing through the southwesterly flow aloft between the
    subtropical ridging that extends through the Southeast states and a
    deep upper low off the central West Coast. Steep mid-level lapse
    rates precede the northern shortwave (i.e. from the northern/central
    Rockies northeastward) and low-level moisture continues to advect
    northward across the southern and central Plains. Both of these
    factors will increase buoyancy ahead of these two shortwaves, which
    are expected to become increasingly phased as they progress
    northeastward throughout the day. This evolution will support a
    large area of thunderstorms from the northern Rockies through the
    southern Plains this afternoon/evening. Environmental conditions
    support strong to isolated severe thunderstorms across these areas,
    with a relatively higher chance of severe from the southern High
    Plains into central TX and along the eastern NE/KS border vicinity.

    Additionally, the West Coast upper low is forecast to progress east-southeastward into southern OR and northern/central CA this
    evening and overnight, supporting the potential for thunderstorms, a
    few of which could be strong.

    ...Southern High Plains into Central Texas...
    Scattered to numerous thunderstorms are expected to develop this
    afternoon across the southern High Plains as a shortwave trough
    lifts out of central Mexico and interacts with the moist and
    modestly buoyant airmass in places over the region. A few initially
    discrete storms are possible, and adequate deep-layer wind shear
    around 35 kt could result in a few instances of severe hail.
    However, weak capping and strong ascent should promote increasing
    thunderstorm coverage, resulting in a transition to a more clustered
    storm mode. Eventual evolution into one or more line segments is
    possible, particularly over southwest TX as low-level flow
    nocturnally strengthens and low-level moisture increases. As this
    transition occurs, damaging gust potential will become the
    predominant hazard. The strengthening low-level flow will also
    lengthen low-level hodograph, supporting the potential for an
    embedded circulation or two, particularly along the southern extent
    of whatever line develops.

    ...Central Plains into the Upper Mississippi Valley...
    Recent surface analysis places a warm front across central KS. This
    warm front is forecast to progress northward throughout the day amid
    persistent southerly flow and resulting moderate/strong low-level
    moisture advection. Given the ongoing cloud cover across the region,
    as well as the showers and thunderstorms over northwest MO, there is
    some uncertainty to how this surface boundary will evolve. General
    expectation is for this front to extend from the central NE vicinity
    into north-central MO by this evening.

    Large, looping low-level hodographs are anticipated in the vicinity
    of this warm front. These profiles, along with dewpoints in the
    low/mid 60s and modestly steep mid-level lapse rates, result in an
    environment that is conditionally favorable for supercells. However,
    some capping will likely linger across the region and large-scale
    forcing will be negligible, casting doubt to whether convective
    initiation will be realized. This uncertainty is matched by the CAM
    guidance, none of which establishes meaningful convection during the
    afternoon and evening. All that to say, if an updraft does mature in
    this environment, all severe hazards are possible, including a
    tornado.

    More certain (but less intense) thunderstorm potential is
    anticipated as low-level warm air advection becomes increasingly
    focused from the central Plains into the upper Mississippi Valley
    this evening and overnight. Moderate elevated buoyancy and
    deep-layer shear support the potential for a few stronger updrafts
    capable of hail as thunderstorms expand northeastward from IA into
    the Upper Midwest.

    ...Northern/Central Rockies...
    Scattered thunderstorm development is anticipated across the
    northern and central Rockies, ahead of a shortwave trough
    progressing northeastward into the region. Deep boundary-layer
    mixing ahead of this system coupled with steep mid-level lapse rates
    and moderate deep-layer vertical shear will result in an environment
    that supports the potential for strong to severe gusts across much
    of the region.

    ...Northern/Central California Coast...
    A frontal band, associated with an upper low moving over the
    northern California coast tonight, is expected to progress
    southeastward through the central CA coastal vicinity this evening. Thermodynamic profiles appear marginally supportive of isolated
    convection deep enough to produce lightning. Winds within the lowest
    1-2 km AGL should increase to around 40 kt as the wave moves
    onshore, which will contribute to the potential for convective
    downdrafts to produce a few locally damaging wind gusts.

    ..Mosier/Squitieri.. 04/11/2026

    $$

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  • From COD Weather Processor@1:2320/107 to wx-storm@lists.illinois.edu on Saturday, April 11, 2026 17:07:28
    ACUS01 KWNS 111707
    SWODY1
    SPC AC 111705

    Day 1 Convective Outlook
    NWS Storm Prediction Center Norman OK
    1205 PM CDT Sat Apr 11 2026

    Valid 111630Z - 121200Z

    ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS THE
    SOUTHERN HIGH PLAINS...

    ...SUMMARY...
    Scattered thunderstorms producing hail and strong wind gusts are
    possible across portions of the southern High Plains this afternoon
    and evening. More isolated strong to severe thunderstorms are
    expected across parts of the central Rockies, central Plains, upper
    Mississippi Valley, and portions of the California coast.

    ...Synopsis...
    Recent satellite imagery reveals two shortwave troughs, one moving
    through the Great Basin and the other moving into central Mexico,
    progressing through the southwesterly flow aloft between the
    subtropical ridging that extends through the Southeast states and a
    deep upper low off the central West Coast. Steep mid-level lapse
    rates precede the northern shortwave (i.e. from the northern/central
    Rockies northeastward) and low-level moisture continues to advect
    northward across the southern and central Plains. Both of these
    factors will increase buoyancy ahead of these two shortwaves, which
    are expected to become increasingly phased as they progress
    northeastward throughout the day. This evolution will support a
    large area of thunderstorms from the northern Rockies through the
    southern Plains this afternoon/evening. Environmental conditions
    support strong to isolated severe thunderstorms across these areas,
    with a relatively higher chance of severe from the southern High
    Plains into central TX and along the eastern NE/KS border vicinity.

    Additionally, the West Coast upper low is forecast to progress east-southeastward into southern OR and northern/central CA this
    evening and overnight, supporting the potential for thunderstorms, a
    few of which could be strong.

    ...Southern High Plains into Central Texas...
    Scattered to numerous thunderstorms are expected to develop this
    afternoon across the southern High Plains as a shortwave trough
    lifts out of central Mexico and interacts with the moist and
    modestly buoyant airmass in places over the region. A few initially
    discrete storms are possible, and adequate deep-layer wind shear
    around 35 kt could result in a few instances of severe hail.
    However, weak capping and strong ascent should promote increasing
    thunderstorm coverage, resulting in a transition to a more clustered
    storm mode. Eventual evolution into one or more line segments is
    possible, particularly over southwest TX as low-level flow
    nocturnally strengthens and low-level moisture increases. As this
    transition occurs, damaging gust potential will become the
    predominant hazard. The strengthening low-level flow will also
    lengthen low-level hodograph, supporting the potential for an
    embedded circulation or two, particularly along the southern extent
    of whatever line develops.

    ...Central Plains into the Upper Mississippi Valley...
    Recent surface analysis places a warm front across central KS. This
    warm front is forecast to progress northward throughout the day amid
    persistent southerly flow and resulting moderate/strong low-level
    moisture advection. Given the ongoing cloud cover across the region,
    as well as the showers and thunderstorms over northwest MO, there is
    some uncertainty to how this surface boundary will evolve. General
    expectation is for this front to extend from the central NE vicinity
    into north-central MO by this evening.

    Large, looping low-level hodographs are anticipated in the vicinity
    of this warm front. These profiles, along with dewpoints in the
    low/mid 60s and modestly steep mid-level lapse rates, result in an
    environment that is conditionally favorable for supercells. However,
    some capping will likely linger across the region and large-scale
    forcing will be negligible, casting doubt to whether convective
    initiation will be realized. This uncertainty is matched by the CAM
    guidance, none of which establishes meaningful convection during the
    afternoon and evening. All that to say, if an updraft does mature in
    this environment, all severe hazards are possible, including a
    tornado.

    More certain (but less intense) thunderstorm potential is
    anticipated as low-level warm air advection becomes increasingly
    focused from the central Plains into the upper Mississippi Valley
    this evening and overnight. Moderate elevated buoyancy and
    deep-layer shear support the potential for a few stronger updrafts
    capable of hail as thunderstorms expand northeastward from IA into
    the Upper Midwest.

    ...Northern/Central Rockies...
    Scattered thunderstorm development is anticipated across the
    northern and central Rockies, ahead of a shortwave trough
    progressing northeastward into the region. Deep boundary-layer
    mixing ahead of this system coupled with steep mid-level lapse rates
    and moderate deep-layer vertical shear will result in an environment
    that supports the potential for strong to severe gusts across much
    of the region.

    ...Northern/Central California Coast...
    A frontal band, associated with an upper low moving over the
    northern California coast tonight, is expected to progress
    southeastward through the central CA coastal vicinity this evening. Thermodynamic profiles appear marginally supportive of isolated
    convection deep enough to produce lightning. Winds within the lowest
    1-2 km AGL should increase to around 40 kt as the wave moves
    onshore, which will contribute to the potential for convective
    downdrafts to produce a few locally damaging wind gusts.

    ..Mosier/Squitieri.. 04/11/2026

    $$

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  • From COD Weather Processor@1:2320/107 to wx-storm@lists.illinois.edu on Saturday, April 11, 2026 20:02:01
    ACUS01 KWNS 112001
    SWODY1
    SPC AC 112000

    Day 1 Convective Outlook
    NWS Storm Prediction Center Norman OK
    0300 PM CDT Sat Apr 11 2026

    Valid 112000Z - 121200Z

    ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS OVER PORTIONS OF NORTH-CENTRAL KANSAS AND SOUTHEASTERN NEBRASKA...

    ...SUMMARY...
    Scattered thunderstorms producing hail and strong wind gusts are
    possible across portions of the southern High Plains and into parts
    of Kansas and Nebraska this afternoon and evening. More isolated
    strong to severe thunderstorms are expected across parts of the
    central Rockies, upper Mississippi Valley, and portions of the
    California coast.

    ...20z Update KS/NE...
    An MCV evident in visible imagery over southwest/central KS is
    forecast to shift northeastward this afternoon toward a differential
    heating zone associated with a modifying remnant outflow boundary
    across northern KS and southern NE. Ample heating south of this zone
    has warmed temperatures ~5-7 degree above model guidance, with
    observation trends suggestive of locally stronger buoyancy and
    vertical shear on modified 12 and 18z RAOBs (1500-2000 J/kg of
    MLCAPE). While overall mid-level flow is modest, some enhancement in
    the low and mid-levels ahead of the MCV is also evident in area
    VADs, bolstering bulk shear to 30-35 kt. Backed low-level winds
    along the retreating boundary are also aiding in maintaining sizable
    clockwise curved low-level hodographs. This could support the
    development of small supercell structures with potential to produce
    tornadoes, particularly near and just north of the retreating
    outflow boundary, and perhaps in close proximity to the MCV.

    Otherwise, some hail and localized strong wind gusts are possible
    with any more robust storms able to develop and maintain themselves
    into this evening. Deep-layer shear is progged to increase after
    dark, as a 40-50 kt low-level jet develops, supporting an increase
    in storm coverage along and north of the boundary tonight. Hail and
    damaging winds would be the primary threats. Given the local
    increase in severe potential, a small zone ahead of the MCV and
    along the boundary has been upgraded to a level 2/5 Slight Risk.

    ...TX and NM...
    Scattered strong to severe thunderstorms remain likely tonight
    across West TX, the Rio Grand Valley and southeastern NM.
    Eventually, one ore more lines or clusters may emerge and spread
    east/northeast into central TX/west-central OK. A risk for damaging
    gusts or a tornado remain possible with these storms into early
    Sunday morning. High-res guidance suggests these storms may maintain
    intensity slightly farther east. The 5% wind are was moved eastward
    to account for the overnight/early morning risk for a few damaging
    gusts.

    Elsewhere, severe storms remain possible over parts of the Rockies
    and West Coast. The outlook remains largely unchanged. See the prior
    discussion for additional information.

    ..Lyons.. 04/11/2026

    .PREV DISCUSSION... /ISSUED 1205 PM CDT Sat Apr 11 2026/

    ...Synopsis...
    Recent satellite imagery reveals two shortwave troughs, one moving
    through the Great Basin and the other moving into central Mexico,
    progressing through the southwesterly flow aloft between the
    subtropical ridging that extends through the Southeast states and a
    deep upper low off the central West Coast. Steep mid-level lapse
    rates precede the northern shortwave (i.e. from the northern/central
    Rockies northeastward) and low-level moisture continues to advect
    northward across the southern and central Plains. Both of these
    factors will increase buoyancy ahead of these two shortwaves, which
    are expected to become increasingly phased as they progress
    northeastward throughout the day. This evolution will support a
    large area of thunderstorms from the northern Rockies through the
    southern Plains this afternoon/evening. Environmental conditions
    support strong to isolated severe thunderstorms across these areas,
    with a relatively higher chance of severe from the southern High
    Plains into central TX and along the eastern NE/KS border vicinity.

    Additionally, the West Coast upper low is forecast to progress east-southeastward into southern OR and northern/central CA this
    evening and overnight, supporting the potential for thunderstorms, a
    few of which could be strong.

    ...Southern High Plains into Central Texas...
    Scattered to numerous thunderstorms are expected to develop this
    afternoon across the southern High Plains as a shortwave trough
    lifts out of central Mexico and interacts with the moist and
    modestly buoyant airmass in places over the region. A few initially
    discrete storms are possible, and adequate deep-layer wind shear
    around 35 kt could result in a few instances of severe hail.
    However, weak capping and strong ascent should promote increasing
    thunderstorm coverage, resulting in a transition to a more clustered
    storm mode. Eventual evolution into one or more line segments is
    possible, particularly over southwest TX as low-level flow
    nocturnally strengthens and low-level moisture increases. As this
    transition occurs, damaging gust potential will become the
    predominant hazard. The strengthening low-level flow will also
    lengthen low-level hodograph, supporting the potential for an
    embedded circulation or two, particularly along the southern extent
    of whatever line develops.

    ...Central Plains into the Upper Mississippi Valley...
    Recent surface analysis places a warm front across central KS. This
    warm front is forecast to progress northward throughout the day amid
    persistent southerly flow and resulting moderate/strong low-level
    moisture advection. Given the ongoing cloud cover across the region,
    as well as the showers and thunderstorms over northwest MO, there is
    some uncertainty to how this surface boundary will evolve. General
    expectation is for this front to extend from the central NE vicinity
    into north-central MO by this evening.

    Large, looping low-level hodographs are anticipated in the vicinity
    of this warm front. These profiles, along with dewpoints in the
    low/mid 60s and modestly steep mid-level lapse rates, result in an
    environment that is conditionally favorable for supercells. However,
    some capping will likely linger across the region and large-scale
    forcing will be negligible, casting doubt to whether convective
    initiation will be realized. This uncertainty is matched by the CAM
    guidance, none of which establishes meaningful convection during the
    afternoon and evening. All that to say, if an updraft does mature in
    this environment, all severe hazards are possible, including a
    tornado.

    More certain (but less intense) thunderstorm potential is
    anticipated as low-level warm air advection becomes increasingly
    focused from the central Plains into the upper Mississippi Valley
    this evening and overnight. Moderate elevated buoyancy and
    deep-layer shear support the potential for a few stronger updrafts
    capable of hail as thunderstorms expand northeastward from IA into
    the Upper Midwest.

    ...Northern/Central Rockies...
    Scattered thunderstorm development is anticipated across the
    northern and central Rockies, ahead of a shortwave trough
    progressing northeastward into the region. Deep boundary-layer
    mixing ahead of this system coupled with steep mid-level lapse rates
    and moderate deep-layer vertical shear will result in an environment
    that supports the potential for strong to severe gusts across much
    of the region.

    ...Northern/Central California Coast...
    A frontal band, associated with an upper low moving over the
    northern California coast tonight, is expected to progress
    southeastward through the central CA coastal vicinity this evening. Thermodynamic profiles appear marginally supportive of isolated
    convection deep enough to produce lightning. Winds within the lowest
    1-2 km AGL should increase to around 40 kt as the wave moves
    onshore, which will contribute to the potential for convective
    downdrafts to produce a few locally damaging wind gusts.

    $$

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  • From COD Weather Processor@1:2320/107 to wx-storm@lists.illinois.edu on Sunday, April 12, 2026 00:58:34
    ACUS01 KWNS 120058
    SWODY1
    SPC AC 120056

    Day 1 Convective Outlook
    NWS Storm Prediction Center Norman OK
    0756 PM CDT Sat Apr 11 2026

    Valid 120100Z - 121200Z

    ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS SOUTHERN TEXAS...

    ...SUMMARY...
    Scattered strong to severe thunderstorms remain possible overnight
    across portions central Texas while more isolated severe
    thunderstorms are expected across the southern and central Plains
    and into the upper Mississippi River Valley.

    ...Synopsis...
    Strong to severe thunderstorms remain possible late this evening and
    into the overnight hours across parts of the central CONUS. A lee
    cyclone will continue to deepen across the northern High Plains and
    maintain northward moisture return across the Plains as well as a
    focused zone of strong isentropic ascent across the upper MS Valley.
    Buoyant conditions and modest, but adequate, deep-layer wind shear
    should continue to support the potential for organized convection.

    ...Texas...
    The early stages of MCV development are noted in regional
    reflectivity across the Big Bend region of TX where a convective
    clustering has been focused over the past several hours. The nearby
    00z DRT RAOB recently sampled a 0-6 km bulk shear value on the order
    of 45 knots, which is favorable for organized convection. This
    kinematic environment remains favorable for organized convection and
    could support intensification/organization of a convective line
    associated with the MCV as it migrates eastward into a more
    moist/buoyant environment. This scenario is supported by recent CAM
    guidance, and warrants maintaining/expanding 15% wind probabilities
    downstream of the MCV.

    ...Oklahoma into Kansas...
    Modestly moist and uncapped conditions were recently sampled across
    northern TX and central OK with effective bulk shear values on the
    order of 25 knots. Continued northward moisture advection should
    modulate nocturnal stabilization, and increasing ascent ahead of the
    upper wave emanating out of northern Mexico may support isolated
    strong to severe convection through the late evening and overnight
    hours.

    ...Upper MS Valley...
    VWPs across the Midwest and upper MS Valley all show a strong
    veering within the lowest 1-2 km and a recent uptick in wind speed
    within this layer. Additionally, upstream RAOBs sampled 7-8 C/km
    lapse rates that should be advecting eastward into the region
    through the overnight hours. The combination of continued ascent and
    increasing instability should promote the potential for additional
    elevated convection late tonight with an attendant threat for hail
    approach severe limits.

    ...California...
    The 00z OAK RAOB sampled weak buoyancy with around 150 J/kg SBCAPE.
    However, temperatures near 700 mb should continue to cool through
    the overnight hours with the approach of an upper wave just off the
    coast. Continued ascent within the left-exit region of the attendant
    upper jet will maintain the potential for isolated convection along
    the CA coast and areas inland. Additionally, 35-45 knot flow within
    the lowest few kilometers will likely be maintained through the
    overnight. Given the expectation of a slight increase in buoyancy
    and maintenance of low-level flow, opted to keep the 5% wind risk.

    ..Moore.. 04/12/2026

    $$

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  • From COD Weather Processor@1:2320/107 to wx-storm@lists.illinois.edu on Sunday, April 12, 2026 06:03:11
    ACUS01 KWNS 120603
    SWODY1
    SPC AC 120601

    Day 1 Convective Outlook
    NWS Storm Prediction Center Norman OK
    0101 AM CDT Sun Apr 12 2026

    Valid 121200Z - 131200Z

    ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS PORTIONS OF
    CENTRAL AND SOUTHERN TEXAS...

    ...SUMMARY...
    Isolated to scattered severe thunderstorms are possible this
    afternoon and evening across parts of the southern High Plains. More
    isolated severe storms will be possible across portions of the Upper
    Great Lakes and northern Rockies.

    ...Synopsis...
    Early-morning surface observations reveal a surface low developing
    across the northern High Plains with a broad fetch of southerly flow
    from the western Gulf into the Plains and Midwest. This broad warm
    sector characterized by mid 50s to low/mid 60s dewpoints will
    largely remain in place through the day as the surface low
    translates east across the Plains into the Great Lakes region
    tonight. The greatest potential for strong/severe thunderstorms will
    reside within this warm sector where regional forcing for ascent
    will support a chance for deep convection.

    ...Southern Plains...
    Latest 00z HREF/REFS guidance, as well as more recent CAM solutions,
    all show considerable variability in the evolution of an ongoing MCS
    through late morning across southern/southeast TX. While most
    solutions depict a steady weakening trend, others - notably the
    WRF-ARW - hint at some continued wind threat across the TX Coastal
    Plain this morning. Regardless, this activity is forecast to
    diminish by late morning/early afternoon, and will likely leave an
    outflow boundary on the western periphery of the cold pool in its
    wake.

    Dewpoints in the low to mid 60s will quickly return northward in the
    wake of the MCS with ensemble guidance depicting a plume of MLCAPE
    values between 1500-2000 J/kg from central TX into western OK by
    mid-afternoon. Thunderstorm development appears possible along any
    residual outflow boundaries across central TX given weak capping
    depicted in forecast soundings, though confidence in precisely where
    this will occur or how widespread storm coverage will be remains
    fairly uncertain. Thunderstorm initiation off the Sierra Del Carmen
    mountains in northern Mexico and along a weak dryline across
    southern KS southward into western OK/TX appears more probable,
    though again, storm coverage will likely remain fairly isolated
    given weak forcing for ascent and some degree of synoptic-scale
    subsidence in the wake of the upper disturbance currently passing
    over the region.

    Convection that can develop within this buoyant and weakly capped
    environment could become fairly intense given favorable
    thermodynamic profiles. Despite some mid-level backing in forecast
    hodographs, effective bulk shear values appear sufficient for a
    large, to perhaps very large hail threat. However, given the
    aforementioned uncertainties in thunderstorm coverage, 15% hail
    probabilities have been confined to where ensemble guidance depicts
    the best overall convective signal.

    ...Minnesota...
    A lee cyclone evident in recent surface observations over the
    northern High Plains will migrate eastward along the U.S./Canaidan
    border through the day, reaching northern MN by around peak heating.
    A narrow tongue of returning moisture may support a corridor of
    sufficient ascent and buoyancy for deep convection. While latest
    guidance remains somewhat mixed on thunderstorm coverage, forecast
    soundings suggest elevated convection may support a threat for large
    hail. Furthermore, several high-res forecast soundings depict an
    environment favorable for surface-based supercells along the frontal
    zone where dewpoints may reach into the mid/upper 50s. While this
    potential appears very low per recent ensemble guidance, some
    tornado threat could materialize along the front where STP values of
    1-2 may emerge.

    ...Northern Rockies...
    A plume of mid-level moisture (PWATs between 0.4 to 0.5 inches) was
    recently observed in regional 00z RAOBs across the Great Basin
    region. This air mass will largely remain in place over the next 24
    hours ahead of an approaching upper low out of northern CA. This
    mid-level moisture will support another day of fairly modest
    surface-based buoyancy (around 250-500 J/kg SBCAPE), but persistent
    30-40 knot flow within the CAPE-bearing layer combined with somewhat
    deep boundary-layer mixing (LCLs forecast to be around 2 km) may
    support another day of strong to severe downburst winds with the
    more robust convective cells.

    ..Moore/Halbert.. 04/12/2026

    $$

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  • From COD Weather Processor@1:2320/107 to wx-storm@lists.illinois.edu on Sunday, April 12, 2026 12:56:36
    ACUS01 KWNS 121256
    SWODY1
    SPC AC 121254

    Day 1 Convective Outlook
    NWS Storm Prediction Center Norman OK
    0754 AM CDT Sun Apr 12 2026

    Valid 121300Z - 131200Z

    ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PORTIONS OF
    TEXAS...

    ...SUMMARY...
    Isolated to scattered severe thunderstorms are possible today into
    evening mainly across parts of Texas and perhaps other nearby parts
    of the southern Plains. More isolated severe storms may occur across
    portions of the Upper Great Lakes and northern Rockies.

    ...Texas/Southern Plains...
    A rather complex scenario exists early today attributable to several
    factors including an MCS that de-intensified/decayed generally near
    I-35 in Texas overnight, with residual cloud cover and outflow
    impacts. Potentially focused in vicinity of outflow, the passing
    mid-level wave and persistent warm/moist advection may support storm persistence and redevelopment/intensification later today across
    central Texas into parts of east Texas and possibly Louisiana within
    a moderately unstable environment.

    In the wake of the mid-level wave, mid-level height rises/subsidence
    are otherwise anticipated coincident with the dryline from central
    Kansas south-southwestward across western Oklahoma and
    west/southwest Texas. The extent and likelihood of storm development
    later today is highly uncertain, but if/where storms do form, the
    environment would generally be supportive of supercells and related
    hazards given ample buoyancy and moderate deep-layer shear.

    ...Minnesota/Wisconsin...
    A surface low over the northern Plains will migrate eastward along
    the U.S./Canadian border through the day, reaching northern
    Minnesota by around peak heating. A narrow tongue of returning
    moisture may support a corridor of sufficient ascent and buoyancy
    for deep convection. A few surface-based supercells could occur
    along the frontal zone where dewpoints may reach into the mid/upper
    50s F. While this potential appears low/uncertain per latest
    guidance, some tornado threat could materialize along the front.
    Hail/wind will otherwise be possible regionally on an isolated
    basis.

    ...Northern Rockies...
    Ahead of an approaching upper wave, mid-level moisture will support
    another day of fairly modest surface-based buoyancy with persistent
    30-40 knot flow within the CAPE-bearing layer. Combined with
    somewhat deep boundary-layer mixing, this may support strong to
    severe downburst winds with the more robust convective cells, mainly
    this afternoon through early evening.

    ..Guyer/Broyles.. 04/12/2026

    $$

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  • From COD Weather Processor@1:2320/107 to wx-storm@lists.illinois.edu on Sunday, April 12, 2026 16:30:39
    ACUS01 KWNS 121630
    SWODY1
    SPC AC 121629

    Day 1 Convective Outlook
    NWS Storm Prediction Center Norman OK
    1129 AM CDT Sun Apr 12 2026

    Valid 121630Z - 131200Z

    ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PORTIONS OF
    SOUTHWEST AND CENTRAL TX...

    ...SUMMARY...
    Isolated to scattered severe thunderstorms are possible today into
    evening mainly across parts of Texas and perhaps other nearby parts
    of the southern Plains. More isolated severe storms may occur across
    portions of the Upper Great Lakes and northern Rockies.

    ...Synopsis...
    Recent satellite imagery shows a pair of phased shortwave troughs
    over the Plains, one moving through the Dakotas and another moving
    through KS/OK. Both of these waves are forecast to continue
    northeastward through the day, with the northern wave reaching
    northwestern Ontario and the southern wave reaching the Great Lakes
    region. This evolution will take these waves east/northeast of the
    higher low-level moisture, which will remain in a corridor from the
    southern Plains northeastward into the Upper Midwest. Showers and
    thunderstorms are anticipated throughout much of this corridor
    today, with highest thunderstorm chances across central/east TX and
    from the Upper Midwest into the Great Lakes.

    Farther west, an upper low is slowly drifting eastward across
    northern CA. Guidance suggests this eastward drift will continue
    today, with several shortwave troughs rotating quickly through the
    base of this system and ejecting across the Great Basin and northern
    Rockies. Large-scale ascent and modest mid-level moisture associated
    with these waves will combine with cold temperatures aloft and
    associated buoyancy to support thunderstorms today from northern CA
    across the northern Great Basin and northern Rockies, and into the
    northern Plains.

    ...Southern/Central Plains...
    Much of this region will be displaced south and west of any notable
    large-scale forcing for ascent. This limited ascent, combined with
    the showers and isolated thunderstorms currently ongoing across
    central and east TX, complicates the overall forecast today, with
    mesoscale factors likely contributing significantly to when and
    where storms develop this afternoon and evening. General expectation
    is for development along the southern and western periphery on the
    ongoing storms (i.e. from southeast/south-central TX into southwest
    TX) later this afternoon and this evening. This redevelopment will
    be supported by a combination of moist advection, modest heating,
    and limited low-level convergence. Moderate to strong buoyancy amid
    moderate vertical shear could support supercells if the mode remains
    discrete. However, the weakness in the mid-level flow suggests
    storms may tend to cluster, a scenario that is supported by most CAM
    guidance. Buoyancy and shear are still strong enough to support
    rotating updrafts and large hail early in the convective cycle, but
    the trends towards a messy convective mode could limit the
    persistence and coverage of robust updrafts. Damaging gusts are
    possible even with the clustered storm mode, especially given there
    is some potential for slightly more organized bowing segments over
    time.

    Farther west, mid-level height rises/subsidence are anticipated
    coincident with the dryline from central Kansas south-southwestward
    across western Oklahoma and west/southwest Texas. The environment, characterized by 1500 to 2000 J/kg of MLCAPE and 30 to 40 kt of
    westerly deep-layer shear, is conditionally supportive of supercells
    capable of all severe hazards. However, the previously mentioned
    height rises and subsidence, combined with modest convective
    inhibition, are generally expected to preclude thunderstorm
    development. Even so, given the conditional risk, Marginal risk
    probabilities will be maintained.

    ...Minnesota/Wisconsin...
    Recent surface analysis places a low just west of FAR, with a warm
    front extending southwestward across central/southeast MN and
    southern WI. This low is forecast to move eastward today, while the
    warm front expands northward. A narrow corridor of surface-based
    buoyancy could develop from north-central MN into far northwest WI
    as dewpoints increase in the upper 50s (perhaps even low 60s).
    Thunderstorm initiation appears possible along the cold front within
    this corridor, although veered low-level flow and northward/westward displacement of the better forcing casts doubt to whether updrafts
    will be maintained. Any storms that do mature within this warm
    sector should become supercells capable of all severe hazards,
    including large hail and tornadoes. However, low confidence in storm development and maturity precludes higher probabilities with this
    outlook.

    ...Northern Rockies...
    Mid-level moisture will support another day of modest surface-based
    buoyancy ahead of the shortwave trough mentioned in the synopsis.
    Persistent 30-40 knot flow within the CAPE-bearing layer combined
    with somewhat deep boundary-layer mixing will support strong to
    severe downburst winds with the more robust convective cells, mainly
    this afternoon through early evening.

    ..Mosier/Squitieri.. 04/12/2026

    $$

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  • From COD Weather Processor@1:2320/107 to wx-storm@lists.illinois.edu on Sunday, April 12, 2026 19:58:42
    ACUS01 KWNS 121958
    SWODY1
    SPC AC 121956

    Day 1 Convective Outlook
    NWS Storm Prediction Center Norman OK
    0256 PM CDT Sun Apr 12 2026

    Valid 122000Z - 131200Z

    ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PORTIONS OF
    CENTRAL TEXAS...

    ...SUMMARY...
    Isolated to scattered severe thunderstorms remain possible today
    into evening mainly across parts of Texas and perhaps other nearby
    parts of the southern Plains. More isolated severe storms may occur
    across portions of the Upper Great Lakes and northern Rockies.

    ...20z Update Central TX...
    Filtered diurnal heating in the wake of earlier showers and storms
    across much of central TX was supporting moderate destabilization
    this afternoon. While mid-level lapse rates are generally poor,
    sufficient destabilization should support a gradual uptick in
    convective coverage this afternoon and evening. With moderate
    deep-layer shear in place, some organization could support a risk
    for damaging gusts, hail, and tornado or two.

    ...MN/WI...
    The aforementioned warm front continues to surge north but has
    slowed farther south than earlier guidance. Weak to moderate
    destabilization along and just south of the boundary will remain
    supportive of a conditions supercell risk this afternoon/evening.
    Strong shear profiles east of the surface low and near the rapidly
    modifying boundary could support a risk for hail and possibly a
    tornado. Have shifted severe probabilities southward slightly to
    better match the observed frontal positioning. See MCD #390 for the
    latest information.

    ...OK/KS/TX Panhandle...
    A conditional risk for a supercell or two remains evident this
    afternoon across the dryline in the central and southern Plains.
    Ample heating in the wake of an early morning MCS could allow for
    isolated storm this afternoon or evening as the dryline is forecast
    to mix eastward before eventually retreating. Forecast guidance
    continues to show weak subsidence suppressing convective
    development, but deepening cumulus evident over the southern TX
    Panhandle could support an isolated storm this evening. All severe
    hazards would be possible.

    ...Intermountain West...
    Steep mid-level lapse rates beneath the cold core of the upper low
    over the West will continue to support scattered high-based storms
    this afternoon. With a relatively dry-sub cloud layer, somewhat deep boundary-layer mixing will support strong to
    severe downburst winds.

    ..Lyons.. 04/12/2026

    .PREV DISCUSSION... /ISSUED 1129 AM CDT Sun Apr 12 2026/

    ...Synopsis...
    Recent satellite imagery shows a pair of phased shortwave troughs
    over the Plains, one moving through the Dakotas and another moving
    through KS/OK. Both of these waves are forecast to continue
    northeastward through the day, with the northern wave reaching
    northwestern Ontario and the southern wave reaching the Great Lakes
    region. This evolution will take these waves east/northeast of the
    higher low-level moisture, which will remain in a corridor from the
    southern Plains northeastward into the Upper Midwest. Showers and
    thunderstorms are anticipated throughout much of this corridor
    today, with highest thunderstorm chances across central/east TX and
    from the Upper Midwest into the Great Lakes.

    Farther west, an upper low is slowly drifting eastward across
    northern CA. Guidance suggests this eastward drift will continue
    today, with several shortwave troughs rotating quickly through the
    base of this system and ejecting across the Great Basin and northern
    Rockies. Large-scale ascent and modest mid-level moisture associated
    with these waves will combine with cold temperatures aloft and
    associated buoyancy to support thunderstorms today from northern CA
    across the northern Great Basin and northern Rockies, and into the
    northern Plains.

    ...Southern/Central Plains...
    Much of this region will be displaced south and west of any notable
    large-scale forcing for ascent. This limited ascent, combined with
    the showers and isolated thunderstorms currently ongoing across
    central and east TX, complicates the overall forecast today, with
    mesoscale factors likely contributing significantly to when and
    where storms develop this afternoon and evening. General expectation
    is for development along the southern and western periphery on the
    ongoing storms (i.e. from southeast/south-central TX into southwest
    TX) later this afternoon and this evening. This redevelopment will
    be supported by a combination of moist advection, modest heating,
    and limited low-level convergence. Moderate to strong buoyancy amid
    moderate vertical shear could support supercells if the mode remains
    discrete. However, the weakness in the mid-level flow suggests
    storms may tend to cluster, a scenario that is supported by most CAM
    guidance. Buoyancy and shear are still strong enough to support
    rotating updrafts and large hail early in the convective cycle, but
    the trends towards a messy convective mode could limit the
    persistence and coverage of robust updrafts. Damaging gusts are
    possible even with the clustered storm mode, especially given there
    is some potential for slightly more organized bowing segments over
    time.

    Farther west, mid-level height rises/subsidence are anticipated
    coincident with the dryline from central Kansas south-southwestward
    across western Oklahoma and west/southwest Texas. The environment, characterized by 1500 to 2000 J/kg of MLCAPE and 30 to 40 kt of
    westerly deep-layer shear, is conditionally supportive of supercells
    capable of all severe hazards. However, the previously mentioned
    height rises and subsidence, combined with modest convective
    inhibition, are generally expected to preclude thunderstorm
    development. Even so, given the conditional risk, Marginal risk
    probabilities will be maintained.

    ...Minnesota/Wisconsin...
    Recent surface analysis places a low just west of FAR, with a warm
    front extending southwestward across central/southeast MN and
    southern WI. This low is forecast to move eastward today, while the
    warm front expands northward. A narrow corridor of surface-based
    buoyancy could develop from north-central MN into far northwest WI
    as dewpoints increase in the upper 50s (perhaps even low 60s).
    Thunderstorm initiation appears possible along the cold front within
    this corridor, although veered low-level flow and northward/westward displacement of the better forcing casts doubt to whether updrafts
    will be maintained. Any storms that do mature within this warm
    sector should become supercells capable of all severe hazards,
    including large hail and tornadoes. However, low confidence in storm development and maturity precludes higher probabilities with this
    outlook.

    ...Northern Rockies...
    Mid-level moisture will support another day of modest surface-based
    buoyancy ahead of the shortwave trough mentioned in the synopsis.
    Persistent 30-40 knot flow within the CAPE-bearing layer combined
    with somewhat deep boundary-layer mixing will support strong to
    severe downburst winds with the more robust convective cells, mainly
    this afternoon through early evening.

    $$

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  • From COD Weather Processor@1:2320/107 to wx-storm@lists.illinois.edu on Monday, April 13, 2026 00:51:42
    ACUS01 KWNS 130051
    SWODY1
    SPC AC 130049

    Day 1 Convective Outlook
    NWS Storm Prediction Center Norman OK
    0749 PM CDT Sun Apr 12 2026

    Valid 130100Z - 131200Z

    ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS PORTIONS OF
    CENTRAL TEXAS...

    ...SUMMARY...
    Isolated to scattered severe thunderstorms remain possible this
    evening across portions of central Texas and perhaps central/western
    Oklahoma.

    ...Synopsis...
    Mid-evening surface observations reveal an expansive warm sector
    from the TX coast northward into the Plains and upper MS Valley.
    Despite a high-quality thermodynamic environment throughout much of
    this warm sector, a combination of residual capping across the upper
    MS Valley and/or very weak ascent in the wake of an upper-level
    disturbance is limiting the overall potential for thunderstorms
    outside of the southern Plains. Across the West, convective coverage
    is gradually diminishing and will continue to dwindle heading into
    the late evening hours as nocturnal cooling begins to increase
    inhibition.

    ...Southern Plains...
    The most intense convection currently resides to the west of the
    I-35 corridor in central TX where strong to severe thunderstorms
    have developed on the western fringe of an expanding cold pool.
    MLCAPE values to the west of the cold pool were recently sampled
    near 2500 J/kg by the DRT and OUN soundings with around 30-35 knots
    of effective bulk shear also noted. This environment is favorable
    for organized convection, including splitting supercells with some
    potential for large to very large hail. However, close proximity to
    the residual cold pool should limit the overall spatial extent of
    this threat, and most guidance depicts this activity waning later
    tonight in the absence of persistent forcing for ascent.

    Further north into western Oklahoma and northwest TX, continued
    cumulus development along a diffuse dryline is noted in GOES
    imagery. While storm development appears unlikely given the
    approaching onset of nocturnal cooling, the downstream environment
    remains highly favorable for intense convection per the 00z OUN
    RAOB, and recent RRFS solutions hint at the potential for convection
    within the next 1-3 hours (though these solutions appear to be
    outliers compared to other guidance). Given this signal and the
    favorable environment, opted to maintain 5% hail/wind probabilities
    to account for this low-probability, but potentially high impact
    scenario.

    ..Moore.. 04/13/2026

    $$

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  • From COD Weather Processor@1:2320/107 to wx-storm@lists.illinois.edu on Monday, April 13, 2026 05:36:13
    ACUS01 KWNS 130536
    SWODY1
    SPC AC 130534

    Day 1 Convective Outlook
    NWS Storm Prediction Center Norman OK
    1234 AM CDT Mon Apr 13 2026

    Valid 131200Z - 141200Z

    ...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF
    THE UPPER MISSISSIPPI RIVER VALLEY...

    ...SUMMARY...
    Severe thunderstorms are likely across the Upper Mississippi Valley
    and Great Lakes region with potential for large to very large hail,
    damaging wind, and tornadoes. A more conditional and isolated risk
    for severe storms is possible across portions of the southern Plains
    late this afternoon and evening.

    ...Synopsis...
    Early-morning water-vapor imagery depicts an upper trough with
    multiple embedded vorticity maxima over the Great Basin. While the
    primary upper wave will remain over the West for today, a leading
    impulse is forecast to eject towards the northern Plains and into
    the Great Lakes through tonight. At the surface, a weak lee cyclone
    over the central High Plains will migrate northeastward in tandem
    with the upper impulse, likely reaching the southern MN vicinity by
    early evening. As this occurs, a plume of mid-60s dewpoints will
    spread north into the upper MS Valley along and south of a warm
    front. Scattered thunderstorm development along and north of the
    warm front is anticipated by late afternoon as forcing for ascent
    gradually increases. Elsewhere, more isolated strong to severe
    thunderstorms are possible across portions of TX and OK where deep
    mixing along a dryline may result in sustained deep convection.

    ...Upper MS Valley...
    A combination of shortwave ridging and capping at the base of an EML
    will limit thunderstorm development through much of the day across
    southern MN into central WI. This will allow for continued moisture
    return as a warm front lifts into the region with MLCAPE values
    forecast to reach 2000-2500 J/kg by around 21 UTC. Thunderstorm
    development will become increasingly probable through the 21-00 UTC
    period as isentropic ascent strengthens ahead of the approaching
    upper disturbance. Lingering inhibition coupled with 45-50 knot
    effective bulk shear should promote initially discrete supercells
    along or just north of the surface boundary. Hodograph elongation
    appears favorable for a large hail threat, possibly as large as 2-3
    inches with the more robust cells. Additionally, enhanced low-level
    SRH along the frontal zone may result in a corridor of relatively
    higher tornado potential if convection can remain rooted along the
    boundary.

    While the overall environment appears very favorable for intense
    convection, east/northeasterly storm motions along or just north of
    the warm front will likely promote storm advection towards the cool
    side of the boundary and clustering/upscale growth through the
    evening. This, combined with capping over the remainder of the warm
    sector, limits confidence in a more widespread tornado threat, and
    could modulate the potential for significant (2+ inch) hail within a
    few hours after convective initiation. Nonetheless, a corridor of
    higher hail potential remains evident in latest guidance along and
    just north of the warm front where discrete supercells are most
    probable. 30% hail probabilities have been shifted to reflect a
    southward trend in frontal placement noted in most recent guidance.

    ...Southern Plains...
    A moist and very unstable air mass will remain in place across TX
    and OK today with MLCAPE values expected to increase to around 2500
    J/kg by late afternoon. Ample diurnal heating/mixing on the western
    periphery of the moisture plume will likely result in weak,
    high-based convection by mid to late afternoon. Easterly storm
    motions may promote downstream intensification as convection
    migrates towards richer low-level moisture, but this will be
    conditional on convection remaining sustained long enough to realize
    the favorable thermodynamic environment. If this can occur,
    deep-layer shear values on the order of 40 knots should promote
    organized convection - likely in the form of supercells - with an
    attendant threat for all hazards, including very large hail. While
    both global and CAM ensemble guidance hint at this potential, the
    lack of appreciable lifting mechanisms (aside from the dryline circulation/boundary-layer mixing) casts considerable uncertainty on
    overall storm coverage.

    ..Moore/Wendt.. 04/13/2026

    $$

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  • From COD Weather Processor@1:2320/107 to wx-storm@lists.illinois.edu on Monday, April 13, 2026 13:01:44
    ACUS01 KWNS 131301
    SWODY1
    SPC AC 131300

    Day 1 Convective Outlook
    NWS Storm Prediction Center Norman OK
    0800 AM CDT Mon Apr 13 2026

    Valid 131300Z - 141200Z

    ...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS ACROSS SOUTHERN
    MINNESOTA AND PARTS OF WISCONSIN...

    ...SUMMARY...
    Severe thunderstorms are likely across the Upper Mississippi Valley
    and Great Lakes region with potential for large to very large hail,
    damaging wind, and tornadoes, mainly late this afternoon into
    tonight. A more conditional and isolated risk for severe storms is
    possible across portions of the southern Plains late this afternoon
    and evening.

    ...Upper Mississippi Valley/Great Lakes including MN/WI...
    Multiple lead mid-level disturbances over the northern High Plains
    will progress northeastward today toward the Upper Midwest, with
    strengthening winds aloft across this region particularly late today
    and tonight. A surface low will tend to deepen/develop
    east-northeastward from northeast Nebraska this morning into far
    southern Minnesota and Wisconsin by tonight in vicinity of a slow-moving/stalled frontal boundary. Low/middle 60s F surface
    dewpoints will advect north-northeastward and become increasingly
    prevalent along/south of the aforementioned stationary/warm front
    this afternoon. MLCAPE values are forecast to reach 2000-2500 J/kg
    by around 21z/4pm CDT.

    Thunderstorm development will become increasingly probable through
    mid/late afternoon (21-00z) as isentropic ascent strengthens ahead
    of the approaching upper disturbance. Lingering inhibition coupled
    with 45-50 kt effective bulk shear should promote initially discrete
    supercells along or just north of the surface boundary. Hodograph
    elongation appears favorable for a large hail threat, possibly as
    large as 2-3 inches in diameter with the more robust cells.
    Additionally, enhanced low-level SRH along the frontal zone is
    expected to result in a corridor of relatively higher tornado
    potential for storms that can remain rooted immediately along the
    boundary.

    While the overall environment appears very favorable for intense convection/supercells, east-northeasterly storm motions along or
    just north of the warm front will likely promote clustering/upscale
    growth through the evening, with an increasing damaging wind
    potential and a continued tornado risk via line-embedded circulation
    potential.

    ...Northern Illinois/northern Indiana and southern Lake Michigan...
    There is the potential that a somewhat separate corridor of
    severe-weather potential may unfold today, potentially born out of
    subtle mid-level wave and early morning convection across northeast
    Missouri vicinity and/or development later today. The initially
    elevated storms would be on the edge of the
    east/northeastward-advecting elevated mixed layer. Steep mid-level
    lapse rates and 35+ kt effective shear could support initially
    isolated hail potential, but a more organized surface-based severe
    risk could manifest if some of the more-aggressive early morning
    short-term guidance trends materialize (HRRR/RAP/RRFS).

    ...Southern Plains including Oklahoma/Texas...
    A moist and potentially unstable air mass will persist regionally to
    the east of a dryline located around peak heating from east-central
    Kansas south-southwestward into west-central Oklahoma and western
    north Texas to the Texas Big Bend vicinity. Immediately east of the
    dryline, warm-sector dewpoints are expected to generally be in the
    middle 60s F, supporting MLCAPE values to 2500-3000 J/kg.

    The extent/likelihood of sustained deep convection later today is a
    key question. The primary southern-stream trough will be well
    upstream over the southwest Desert, with neutral height tendencies
    across the southern Plains, although early morning water vapor
    imagery and derived wind data suggest that a subtle disturbance over
    northern Mexico and the southern Rockies could approach the
    dryline/warm sector later today.

    Regardless, ample post-dryline mixing and near-dryline
    confluence/weak convergence may be sufficient for deep convective
    initiation after 21z/4pm CDT, at least an isolated basis. Forecast
    mass fields would imply that this is most probable across
    central/southwest Oklahoma into the north Texas Big Country, and
    perhaps somewhat separately across the Texas Big Bend and Rio Grande
    vicinity.

    If/where storms develop and mature, deep-layer shear on the order of
    40+ kt will support supercells, potentially capable of all hazards
    including very large hail. An increased confidence in deep
    convective initiation late this afternoon/early evening could
    warrant focus Slight Risk delineations in subsequent Day 1 updates.

    ...Northern High Plains...
    Generally isolated severe storms capable of hail/wind will be
    possible late this afternoon into evening along/north of the surface
    front where modest low-level moisture and vertical shear will be
    maximized, in the presence of steep low/mid-level lapse rates.

    ..Guyer/Broyles.. 04/13/2026

    $$

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  • From COD Weather Processor@1:2320/107 to wx-storm@lists.illinois.edu on Monday, April 13, 2026 16:38:46
    ACUS01 KWNS 131638
    SWODY1
    SPC AC 131636

    Day 1 Convective Outlook
    NWS Storm Prediction Center Norman OK
    1136 AM CDT Mon Apr 13 2026

    Valid 131630Z - 141200Z

    ...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS ACROSS SOUTHERN MINNESOTA...FAR NORTHERN IOWA...AND PARTS OF WISCONSIN...

    ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS THE
    SOUTHERN PLAINS...

    ...SUMMARY...
    Severe thunderstorms are likely across the Upper Mississippi Valley
    and Great Lakes region with potential for large to very large hail,
    damaging wind, and tornadoes, mainly late this afternoon into
    tonight. A more isolated risk for severe storms is possible across
    portions of the southern Plains late this afternoon and evening.

    ...Upper Mississippi Valley/Great Lakes including MN/WI/IA...
    Multiple lead mid-level disturbances over the northern High Plains
    will progress northeastward today toward the Upper Midwest, with
    strengthening winds aloft across this region particularly late today
    and tonight. A surface low will tend to deepen/develop
    east-northeastward from northeast Nebraska into far southern
    Minnesota and Wisconsin by tonight in vicinity of a
    slow-moving/stalled frontal boundary. Low/middle 60s F surface
    dewpoints will advect north-northeastward and become increasingly
    prevalent along/south of the aforementioned stationary/warm front
    this afternoon. MLCAPE values are forecast to reach 2000-2500 J/kg
    by around 21z/4pm CDT.

    Thunderstorm development will become increasingly probable through
    mid/late afternoon (21-00z) as isentropic ascent strengthens ahead
    of the approaching upper disturbance. This should especially be the
    case near the primary boundary. However, semi-discrete warm sector supercellular development, across areas such as southern Wisconsin,
    cannot be ruled out. Lingering inhibition coupled with 45-50 kt
    effective bulk shear should promote initially discrete supercells.
    Hodograph elongation appears favorable for a large hail threat,
    possibly as large as 2-3 inches in diameter with the more robust
    cells. Additionally, enhanced low-level SRH along the frontal zone
    is expected to result in a corridor of relatively higher tornado
    potential for storms that can remain rooted immediately along the
    boundary.

    While the overall environment appears very favorable for intense convection/supercells, east-northeasterly storm motions along or
    just north of the warm front will likely promote clustering/upscale
    growth through the evening, with an increasing damaging wind
    potential and a continued tornado risk via line-embedded
    circulations.

    ...Northern Illinois/northern Indiana and southern Lake Michigan...
    See Mesoscale Discussion 395 for short-term details. There is the
    potential that a somewhat separate corridor of severe-weather
    potential today, potentially via a subtle mid-level wave and morning
    convection across northeast Missouri/northwest Illinois vicinity
    and/or additional development later today. The initially elevated
    storms are on the edge of the east/northeastward-advecting elevated
    mixed layer. Steep mid-level lapse rates and 35+ kt effective shear
    could support initially isolated hail potential, but a more
    organized surface-based severe risk could materialize later this
    afternoon, although the specific details remain uncertain.

    ...Southern Plains including Oklahoma/Texas...
    Confidence/potential for isolated to widely scattered locally
    intense storms later this afternoon has incrementally increased,
    although specifics regarding the extent of convective initiation are
    still uncertain.

    A moist and potentially unstable air mass will persist regionally to
    the east of a dryline located around peak heating from east-central
    Kansas south-southwestward into west-central Oklahoma and western
    north Texas to the Texas Big Bend vicinity. Immediately east of the
    dryline, warm-sector dewpoints are expected to generally be in the
    middle 60s F, supporting MLCAPE values to 2500-3000 J/kg. A subtle
    disturbance over northern Mexico and the southern Rockies could
    approach the dryline/warm sector later today.

    Regardless, ample post-dryline mixing and near-dryline
    confluence/weak convergence should be sufficient for isolated deep
    convective initiation after 21z/4pm CDT. Forecast mass fields and
    some short-term guidance would imply that this is most probable
    across central/southwest Oklahoma into the north Texas Big Country,
    and perhaps somewhat separately across the Texas Big Bend and Rio
    Grande vicinity.

    If/where storms develop and mature, deep-layer shear on the order of
    40+ kt will support supercells, potentially capable of all hazards
    including very large hail.

    ...Northern High Plains...
    Generally isolated severe storms including a few low-topped
    supercells capable of hail/wind are possible late this afternoon
    into evening along/north of the surface front. This is where modest
    low-level moisture and vertical shear will be maximized, in the
    presence of steep low/mid-level lapse rates.

    ..Guyer/Chalmers.. 04/13/2026

    $$

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  • From COD Weather Processor@1:2320/107 to wx-storm@lists.illinois.edu on Monday, April 13, 2026 19:57:46
    ACUS01 KWNS 131957
    SWODY1
    SPC AC 131956

    Day 1 Convective Outlook
    NWS Storm Prediction Center Norman OK
    0256 PM CDT Mon Apr 13 2026

    Valid 132000Z - 141200Z

    ...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS OVER PARTS OF
    SOUTHERN MINNESOTA...NORTHERN IOWA...AND CENTRAL WISCONSIN...

    ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS OVER PARTS OF TEXAS...OKLAHOMA AND THE CENTRAL GREAT LAKES....

    ...SUMMARY...
    Severe thunderstorms remain likely across the Upper Mississippi
    Valley and Great Lakes region with potential for large to very large
    hail, damaging wind, and tornadoes, mainly late this afternoon into
    tonight. A more isolated risk for severe storms is possible across
    portions of the southern Plains late this afternoon and evening.

    ...20z Update Upper Midwest...
    Afternoon visible imagery showed diurnal heating ongoing south of
    the stalled front from the eastern SD across southern MN into
    central WI. Moderate destabilization should support scattered to
    numerous thunderstorms this afternoon and evening. Initially
    supercells are likely, given strongly veering wind profiles and
    moderate deep-layer flow. All hazards are possible with these
    storms. With time, upscale growth into one or more lines or clusters
    appears likely as storms spread eastward into the Great Lakes.

    Convective development appears likely along the triple point near
    the surface low from northeast/eastern NE into southeastern SD.
    Supercell wind profiles and moderate buoyancy would support a risk
    for large hail and some damaging wind gusts. A tornado or two may
    occur as any supercells that develop move eastward into deeper
    low-level moisture across northwestern IA and southern MN.

    ...Southern and Central Plains...
    Towering cumulus along a dryline over parts of KS/OK/TX may support
    isolated storm development late this afternoon. A conditionally
    favorable environment (3000+ j/kg of MLCAPE and 35-40 kt effective
    shear) for supercells will support a risk for all hazards. See MCD
    #399 for short term information. The primary change for this outlook
    was to extend severe probabilities northeastward into eastern KS.
    Guidance and observational trends have shown an increased likelihood
    of a storm or two this afternoon.

    ..Lyons.. 04/13/2026

    .PREV DISCUSSION... /ISSUED 1136 AM CDT Mon Apr 13 2026/

    ...Upper Mississippi Valley/Great Lakes including MN/WI/IA...
    Multiple lead mid-level disturbances over the northern High Plains
    will progress northeastward today toward the Upper Midwest, with
    strengthening winds aloft across this region particularly late today
    and tonight. A surface low will tend to deepen/develop
    east-northeastward from northeast Nebraska into far southern
    Minnesota and Wisconsin by tonight in vicinity of a
    slow-moving/stalled frontal boundary. Low/middle 60s F surface
    dewpoints will advect north-northeastward and become increasingly
    prevalent along/south of the aforementioned stationary/warm front
    this afternoon. MLCAPE values are forecast to reach 2000-2500 J/kg
    by around 21z/4pm CDT.

    Thunderstorm development will become increasingly probable through
    mid/late afternoon (21-00z) as isentropic ascent strengthens ahead
    of the approaching upper disturbance. This should especially be the
    case near the primary boundary. However, semi-discrete warm sector supercellular development, across areas such as southern Wisconsin,
    cannot be ruled out. Lingering inhibition coupled with 45-50 kt
    effective bulk shear should promote initially discrete supercells.
    Hodograph elongation appears favorable for a large hail threat,
    possibly as large as 2-3 inches in diameter with the more robust
    cells. Additionally, enhanced low-level SRH along the frontal zone
    is expected to result in a corridor of relatively higher tornado
    potential for storms that can remain rooted immediately along the
    boundary.

    While the overall environment appears very favorable for intense convection/supercells, east-northeasterly storm motions along or
    just north of the warm front will likely promote clustering/upscale
    growth through the evening, with an increasing damaging wind
    potential and a continued tornado risk via line-embedded
    circulations.

    ...Northern Illinois/northern Indiana and southern Lake Michigan...
    See Mesoscale Discussion 395 for short-term details. There is the
    potential that a somewhat separate corridor of severe-weather
    potential today, potentially via a subtle mid-level wave and morning
    convection across northeast Missouri/northwest Illinois vicinity
    and/or additional development later today. The initially elevated
    storms are on the edge of the east/northeastward-advecting elevated
    mixed layer. Steep mid-level lapse rates and 35+ kt effective shear
    could support initially isolated hail potential, but a more
    organized surface-based severe risk could materialize later this
    afternoon, although the specific details remain uncertain.

    ...Southern Plains including Oklahoma/Texas...
    Confidence/potential for isolated to widely scattered locally
    intense storms later this afternoon has incrementally increased,
    although specifics regarding the extent of convective initiation are
    still uncertain.

    A moist and potentially unstable air mass will persist regionally to
    the east of a dryline located around peak heating from east-central
    Kansas south-southwestward into west-central Oklahoma and western
    north Texas to the Texas Big Bend vicinity. Immediately east of the
    dryline, warm-sector dewpoints are expected to generally be in the
    middle 60s F, supporting MLCAPE values to 2500-3000 J/kg. A subtle
    disturbance over northern Mexico and the southern Rockies could
    approach the dryline/warm sector later today.

    Regardless, ample post-dryline mixing and near-dryline
    confluence/weak convergence should be sufficient for isolated deep
    convective initiation after 21z/4pm CDT. Forecast mass fields and
    some short-term guidance would imply that this is most probable
    across central/southwest Oklahoma into the north Texas Big Country,
    and perhaps somewhat separately across the Texas Big Bend and Rio
    Grande vicinity.

    If/where storms develop and mature, deep-layer shear on the order of
    40+ kt will support supercells, potentially capable of all hazards
    including very large hail.

    ...Northern High Plains...
    Generally isolated severe storms including a few low-topped
    supercells capable of hail/wind are possible late this afternoon
    into evening along/north of the surface front. This is where modest
    low-level moisture and vertical shear will be maximized, in the
    presence of steep low/mid-level lapse rates.

    $$

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  • From COD Weather Processor@1:2320/107 to wx-storm@lists.illinois.edu on Tuesday, April 14, 2026 00:56:22
    ACUS01 KWNS 140056
    SWODY1
    SPC AC 140054

    Day 1 Convective Outlook
    NWS Storm Prediction Center Norman OK
    0754 PM CDT Mon Apr 13 2026

    Valid 140100Z - 141200Z

    ...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF
    THE UPPER MISSISSIPPI RIVER VALLEY...

    ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS FAR EASTERN
    KANSAS AND FAR WESTERN MISSOURI...

    ...SUMMARY...
    Severe thunderstorms will continue across the Upper Mississippi
    Valley and Great Lakes region with potential for large to very large
    hail, damaging wind, and tornadoes, through the overnight hours. A
    more focused risk for severe storms will continue through late
    evening across the southern to central Plains.

    ...Synopsis...
    Late-evening surface analysis reveals a slow-moving surface low over
    eastern NE with a warm frontal zone draped eastward into southern MN
    and central WI. Scattered strong to severe thunderstorms are ongoing
    along the frontal zone as of 01 UTC and will likely continue through
    much of the overnight hours across the upper MS Valley and the
    Midwest. Further south, several attempts at convective initiation
    have been noted along a dryline draped from eastern NE southward
    into KS, OK, and TX. Although additional attempts at thunderstorm
    development are possible over the next few hours, the primary severe
    risk will be focused across the Kansas City metro area where a
    cluster of supercells has emerged.

    ....Upper MS Valley/Midwest...
    Scattered supercells are ongoing across southern MN and into central
    WI along and north of the surface warm front. A tornado and
    significant (2+ inch) hail threat will likely persist for the next
    couple of hours, but the expectation is for increased storm
    clustering and upscale growth through the overnight hours. The
    developing MCS will likely spread east/southeast into southern WI
    and possibly northern IL prior to 12 UTC Tuesday with an attendant
    risk for severe winds.

    ...Eastern Kansas/western Missouri...
    A cluster of supercells has emerged across eastern KS over the past
    few hours and will likely continue to spread east into western MO
    through late evening. Given very favorable thermodynamic and
    kinematics noted in the 00z TOP sounding, this activity will likely
    continue to pose a threat for very large hail and tornadoes. 15%
    hail and 5% tornado probabilities have been introduced to account
    for this localized threat.

    ...Southern Plains...
    GOES imagery over the past few hours has shown several attempts at
    convective initiation across OK and TX; however, most of these
    attempts have failed due to very meager/localized ascent along the
    dryline. While one strong storm is noted across northwest TX, the
    potential for new storm development should wane through the evening
    given residual inhibition noted in 00z soundings and as nocturnal
    cooling begins to diminish the dryline circulation. Because of this,
    opted to remove 15% risk probabilities, but maintain some risk
    probabilities given the ongoing convection and otherwise very
    favorable convective environment.

    ..Moore.. 04/14/2026

    $$

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  • From COD Weather Processor@1:2320/107 to wx-storm@lists.illinois.edu on Tuesday, April 14, 2026 05:51:54
    ACUS01 KWNS 140551
    SWODY1
    SPC AC 140550

    Day 1 Convective Outlook
    NWS Storm Prediction Center Norman OK
    1250 AM CDT Tue Apr 14 2026

    Valid 141200Z - 151200Z

    ...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS ACROSS PORTIONS
    OF THE MIDWEST...

    ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS THE CENTRAL
    TO SOUTHERN PLAINS AND PARTS OF THE NORTHEAST...

    ...SUMMARY...
    Severe thunderstorms are expected this afternoon through tonight
    from the southern Plains to the Great Lakes. Large to very large
    hail, a few tornadoes (some strong), and damaging wind gusts will be
    possible, particularly across parts of eastern Iowa, northern
    Illinois, and southern Wisconsin. Additional severe storms, mainly
    producing strong wind gusts, will be possible across parts of the
    Northeast this afternoon.

    ...Synopsis...
    An upper wave is evident in recent water-vapor imagery across the
    southern Great Basin. This trough will translate east into the
    Plains through today, reaching the Great Lakes region by tonight.
    This will support slight deepening of a diffuse surface low analyzed
    over the central High Plains as it drifts east towards the lower MO
    River Valley. Ahead of the low, an expansive warm sector
    (characterized by widespread mid to upper 60s dewpoints) remains in
    place from the southern Plains northeastward into the upper MS
    Valley region. Strong to severe thunderstorms are expected along a
    composite outflow boundary/warm front from eastern IA into southern
    WI/northern IL as well as along a dryline draped from eastern KS
    into OK and TX. Further east, a mid-level wave associated with
    ongoing convection over the Great Lakes will support re-intensification/re-development of strong/severe storms across the
    Northeast.

    ...Midwest...
    An outflow boundary emanating from the ongoing MCS across the Great
    Lakes will likely be draped across the Midwest early this morning.
    This boundary is forecast to drift northward within a southerly flow
    regime as an effective warm front ahead of the approaching surface
    low and upper wave. Latest guidance generally depicts this boundary
    stalling across eastern IA into southern WI by late afternoon when
    daytime heating and ascent ahead of the upper wave will erode
    inhibition and promote convective initiation along the boundary.

    Dewpoints in the mid to upper 60s coupled with steep mid-level lapse
    rates (already noted in upstream 00z RAOBs) will support MLCAPE
    values near 2500 J/kg by late afternoon. Moderate buoyancy combined
    with 45-55 knots of effective bulk shear will be highly favorable
    for organized convection. Capping at the base of the EML should
    initially limit thunderstorm coverage and favor discrete supercells
    along the boundary. In addition to very large hail (possibly up to
    2-3 inches in diameter), enhanced low-level SRH along the boundary
    may support a corridor of locally higher tornado potential,
    including the potential for significant tornadoes. With time,
    easterly storm motions along the boundary will promote upscale
    growth with an increasing wind threat heading into the late evening
    hours.

    The primary uncertainty will be the location of the boundary by late
    afternoon. 30% hail and 10% tornado probabilities were adjusted to
    reflect the most likely placement of the boundary based on a
    consensus of guidance; however, exact placement of the boundary will
    be conditional on the precise evolution of the morning MCS.
    Similarly, how quickly upscale growth occurs after initiation may
    modulate the duration of the significant hail/tornado threat.

    ...Kansas into Oklahoma and Texas...
    Modest height falls across the central to southern Plains combined
    with weak convergence along the dryline will likely support isolated
    to perhaps scattered thunderstorms from eastern KS southward into TX
    this afternoon. Consensus among latest HREF/REFS guidance is that
    initiation is most probable across northwest TX into central OK -
    possibly ahead of a subtle mid-level wave, though in reality the
    unfocused nature of the broad-scale ascent suggests that initiation
    will be possible anywhere along the dryline where low-level
    convergence can be maximized. Regardless, ample buoyancy within the
    warm sector (2500-3000 J/kg MLCAPE sampled in evening RAOBs) coupled
    with 30-40 knots of effective bulk shear will support supercells
    with an attendant threat for large hail (possibly exceeding 2 inches
    in diameter). Some tornado threat will likely materialize around and
    after 00 UTC as the nocturnal jet strengthens and enlarges low-level hodographs.

    ...Northeast...
    A low-amplitude upper wave associated with an ongoing MCS across the
    Great Lakes will migrate eastward towards the Northeast through the
    day. Residual convection associated with the MCS may linger through
    morning before re-intensifying by early afternoon as daytime heating
    supports steepening low-level lapse rates and increasing MLCAPE
    values (likely up to the 500-1000 J/kg range). While buoyancy will
    likely remain weak, 35-40 knot bulk shear through the CAPE-bearing
    layer and focused ascent ahead of a low-amplitude upper wave will
    likely support organization of convective bands with an attendant
    threat for strong to severe winds.

    ..Moore/Wendt.. 04/14/2026

    $$

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  • From COD Weather Processor@1:2320/107 to wx-storm@lists.illinois.edu on Tuesday, April 14, 2026 12:39:26
    ACUS01 KWNS 141239
    SWODY1
    SPC AC 141237

    Day 1 Convective Outlook
    NWS Storm Prediction Center Norman OK
    0737 AM CDT Tue Apr 14 2026

    Valid 141300Z - 151200Z

    ...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS FOR IOWA INTO
    THE SOUTHERN GREAT LAKES AND PORTIONS OF OKLAHOMA...

    ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FOR PARTS OF THE
    NORTHEAST...

    ...SUMMARY...
    Severe thunderstorms are expected this afternoon through tonight
    from the southern Plains into the Midwest. Large to giant hail,
    several tornadoes (some strong), and severe gusts will be possible, particularly from Iowa into the southern Great Lakes.

    ...Midwest...
    An MCV near the IL-IN border this morning and southward-moving
    outflow are linked to thunderstorms over parts of the eastern Corn
    Belt. This outflow boundary will likely stall with the western
    portion of the boundary advancing northward within a strengthening
    warm conveyor this afternoon. Guidance generally depicts this
    boundary stalling across eastern IA into southern WI by late
    afternoon when daytime heating and ascent ahead of the upper wave
    will erode inhibition and promote convective initiation along the
    boundary. A moist airmass upstream over the lower MO Valley will
    advect northeast beneath steep 700-500 mb lapse rates (reference the
    12 UTC Topeka, KS raob). MLCAPE at or above 2500 J/kg is forecast
    by mid-late afternoon from IA into the IA-WI-IL border vicinity.
    Initial storms later this afternoon will rapidly become supercells
    with all severe hazards possible. Large to giant hail and an
    intense tornado will be possible with the more mature/strongest
    supercells where SRH is locally maximized near the boundary.
    Upscale growth into a severe cluster is forecast to eventually
    evolve during the evening aided by a strong southwesterly LLJ into
    the southern Great Lakes. If a supercell develops ahead of the
    eastward-moving cluster, a tornado threat could develop as the
    boundary layer quickly recovers/destabilizes.

    ...Kansas into Oklahoma and Texas...
    Modest height falls across the central to southern Plains combined
    with weak convergence along the dryline will likely support
    scattered thunderstorms from eastern KS southward into western north
    TX this afternoon into the evening. Aligning with earlier thinking,
    strong heating and perhaps weak ascent tied to a subtle mid-level
    wave, will favor storm development by 20-22z as convective
    inhibition erodes. A very unstable airmass characterized by
    2500-3000 J/kg MLCAPE and elongated hodographs will strongly favor
    supercells. The strength of low-level shear remains unclear during
    the early evening, when the tornado risk could maximize.
    Nonetheless, increased confidence in widely scattered to scattered
    supercells yielding a risk for large to giant hail prompted an
    increase in hail and hail-intensity highlights this outlook update.

    ...Northeast...
    A low-amplitude disturbance associated with an ongoing MCS near Lake
    Ontario this morning will move east into the Northeast during the
    day. Cloud breaks and low-level warm/moist advection will
    contribute to a destabilizing airmass by midday. Veering and
    strengthening winds with height will support storm organization,
    including the potential for supercells. Eventually a band of storms
    is forecast to evolve by mid-late afternoon with wind damage being
    the primary risk. Have introduced low hail/tornado probabilities to
    account for hazards associated with supercells.

    ..Smith/Dean.. 04/14/2026

    $$

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  • From COD Weather Processor@1:2320/107 to wx-storm@lists.illinois.edu on Tuesday, April 14, 2026 16:32:26
    ACUS01 KWNS 141632
    SWODY1
    SPC AC 141630

    Day 1 Convective Outlook
    NWS Storm Prediction Center Norman OK
    1130 AM CDT Tue Apr 14 2026

    Valid 141630Z - 151200Z

    ...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF
    THE MIDWEST/SOUTHERN GREAT LAKES AND SOUTHERN/CENTRAL PLAINS...

    ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF
    THE NORTHEAST...

    ...SUMMARY...
    Severe thunderstorms are expected this afternoon through tonight
    from the southern Plains into the Midwest. Large to giant hail,
    several tornadoes (some strong), and swaths of severe/damaging gusts
    are all likely, particularly from Iowa into the southern Great
    Lakes.

    ...Synopsis...
    An active severe weather day is anticipated for much of the
    southern/central Plains into the Midwest/Great Lakes and parts of
    the Northeast. The primary upper trough centered over the Four
    Corners late this morning will eject east-northeastward towards the southern/central Plains by this evening, while a separate mid-level
    shortwave trough over the northern Plains/Upper Midwest will also
    move east-northeastward across the Upper Great Lakes into Ontario.
    Another convectively enhanced low-amplitude shortwave trough will
    also develop eastward across the Lower Great Lakes into the
    Northeast.

    Recent surface analysis indicates multiple surface lows, with one
    over southern Ontario and another over southeast NE/northeast KS. A
    seasonably rich/moist low-level airmass exists to the south of a
    front extending between these two lows, with surface dewpoints
    already in the low to mid 60s across much of the southern/central
    Plains to the east of a dryline. Both the dryline in the
    southern/central Plains and developing warm front in the
    Midwest/southern Great Lakes will likely serve as foci for intense thunderstorms this afternoon and evening, including the potential
    for several supercells.

    ...Midwest/Ohio Valley/Great Lakes...
    A complex scenario for severe thunderstorms remains apparent across
    the Midwest/OH Valley into the southern Great Lakes today, with
    multiple outflow boundaries from earlier convection rendering
    greater than usual uncertainty with the southward extent of possible thunderstorm development in IL/IN/OH. In general, continued
    low-level warm advection from the central Plains into the Midwest/OH
    Valley will support a moistening/destabilizing airmass through the
    afternoon as a northern-stream shortwave trough moves eastward
    across the Upper Midwest. A surface warm front will extend
    northeastward from a weak surface low in IA across southern WI and
    Lower MI. It still appears likely that multiple intense supercells
    will develop by 20-21Z along/near this boundary in IA/southern
    WI/northern IL in a very favorable airmass for significant severe
    hail given strong deep-layer shear and the presence of steep
    mid-level lapse rates. Low-level shear is expected to gradually
    strengthen through the evening in tandem with a modestly increasing south-southwesterly low-level jet.

    Any supercells than can remain on the warm/south side of the front
    will be capable of producing tornadoes, a few of which could be
    strong (EF-2/3). Some consideration was given to including greater
    tornado probabilities and a Moderate Risk (level 4 of 5) focused
    across southern WI/far northern IL. But, convection may have a
    tendency to grow upscale fairly quickly this evening, so confidence
    was not high enough for a categorical upgrade at this time.
    Regardless, very large to giant hail (potentially up to 3-4 inches
    in diameter) will be a threat with sustained supercells, and a swath
    of severe/damaging winds appears likely with a convective cluster
    spreading eastward across southern Lower MI this evening into
    tonight.

    A somewhat separate area of severe potential should also exist
    farther south across central IL into IN/OH this afternoon and
    evening. Greater low-level moisture and related instability are
    expected to exist across these areas compared to locations farther
    north. While large-scale forcing should remain fairly weak/nebulous
    across this region, a remnant outflow boundary may provide a focus
    for supercell development across central IL into IN by 20-21Z. Have
    expanded the Slight Risk for large hail, damaging winds, and perhaps
    a few tornadoes southward across these areas to account for this
    still somewhat uncertain potential.

    ...Southern/Central Plains...
    12Z observed soundings from DRT/MAF/FWD/OUN/TOP show the presence of
    steep mid-level lapse rates atop rich low-level moisture (generally
    14-15 g/kg mean mixing ratios) along/east of the surface dryline.
    Southwesterly mid-level flow and modest ascent preceding the upper
    trough over the Southwest/southern Rockies will gradually overspread
    the warm sector by mid to late afternoon. Moderate to strong
    instability (MLCAPE around 2000-3000 J/kg, locally stronger
    possible) and 35-45 kt of deep-layer shear will support multiple
    intense supercells. Explosive convective initiation across parts of
    western OK into south-central/southeast KS is expected by 20-21Z as
    lingering MLCIN erodes with filtered daytime heating and as
    convective temperatures are breached.

    The overall thermodynamic and kinematic environment appears quite
    favorable for very large to potentially giant hail (up to 3-4 inches
    in diameter) with any supercells that spread east-northeastward
    through the afternoon/evening. A gradually strengthening low-level
    jet across OK/KS by 00Z will also support a threat for a few
    tornadoes, a couple of which could be strong as low-level hodographs
    become enlarged. Gradual upscale growth/clustering should occur with
    time through the evening, with some risk for severe/damaging winds.
    The Enhanced Risk has been expanded a bit northeastward into south-central/southeast KS for a focused severe wind corridor.
    Farther south along the length of the dryline in TX, isolated to
    scattered supercells may develop this afternoon and evening, with a
    risk for mainly large to very large hail and occasional severe
    gusts.

    ...Northeast...
    Ongoing convection across southern Ontario and the Lower Great Lakes
    will continue to track eastward this afternoon into NY and parts of
    New England in tandem with a low-amplitude shortwave trough. Gradual
    clearing of low/mid-level clouds has already encouraged surface
    temperatures to warm into the 70s along/south of west-east oriented
    front. Thunderstorms are expected to gradually increase in coverage
    and intensity as weak to locally moderate instability and strong
    deep-layer shear support organized updrafts, including the potential
    for some supercells initially. The greatest severe risk will
    probably be scattered damaging winds given a tendency for convection
    to consolidate into one or more clusters. But, an isolated severe
    hail threat may exist with any sustained supercell, along with some
    chance for a tornado or two near the front where low-level shear
    will be locally enhanced.

    ..Gleason/Chalmers.. 04/14/2026

    $$

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  • From COD Weather Processor@1:2320/107 to wx-storm@lists.illinois.edu on Tuesday, April 14, 2026 19:38:32
    ACUS01 KWNS 141938
    SWODY1
    SPC AC 141936

    Day 1 Convective Outlook
    NWS Storm Prediction Center Norman OK
    0236 PM CDT Tue Apr 14 2026

    Valid 142000Z - 151200Z

    ...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF
    THE MIDWEST/SOUTHERN GREAT LAKES AND SOUTHERN/CENTRAL PLAINS...

    ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF
    THE NORTHEAST...

    ...SUMMARY...
    Severe thunderstorms are expected this afternoon through tonight
    from the southern Plains into the Midwest. Large to giant hail,
    several tornadoes (some strong), and swaths of severe/damaging gusts
    are all likely, particularly from Iowa into the southern Great
    Lakes.

    ...20Z Update...
    A complex yet active severe weather day remains in the forecast for
    portions of the Midwest-OH Valley into the Southern Plains this
    afternoon into early tonight. While several lines were slightly
    adjusted to account for the latest guidance consensus, the following substantial changes and/or decisions were made:

    1.) 30 percent wind probabilities were expanded southwestward into
    southwest and central OK to account for the possibility of more
    rapid upscale growth into one or more wind-producing MCSs or linear
    segments.

    2.) Category 1/Marginal Risk probabilities for severe wind and hail
    were expanded west-southwest into NE along a frontal boundary to
    account for two possible scenarios. First, an isolated strong storm
    may develop within the next few hours along the boundary as a
    consequence of strong diurnal heating. Second, late tonight, there
    is low potential for gravity-wave associated convection on the
    immediate cool side of the frontal boundary, atop a stable boundary
    layer.

    3.) Confidence is still too low for supercells across the Midwest to
    remain discrete for long periods of time, which would warrant a
    Categorical Moderate risk upgrade. Nonetheless, should a dominant
    supercell become sustained and discrete for at least a few hours,
    especially along the warm front over northeast IA into southern WI,
    a sustained and intense tornado will be possible.

    The rest of the forecast (see below) remains on track.

    ..Squitieri.. 04/14/2026

    .PREV DISCUSSION... /ISSUED 1130 AM CDT Tue Apr 14 2026/

    ...Synopsis...
    An active severe weather day is anticipated for much of the
    southern/central Plains into the Midwest/Great Lakes and parts of
    the Northeast. The primary upper trough centered over the Four
    Corners late this morning will eject east-northeastward towards the southern/central Plains by this evening, while a separate mid-level
    shortwave trough over the northern Plains/Upper Midwest will also
    move east-northeastward across the Upper Great Lakes into Ontario.
    Another convectively enhanced low-amplitude shortwave trough will
    also develop eastward across the Lower Great Lakes into the
    Northeast.

    Recent surface analysis indicates multiple surface lows, with one
    over southern Ontario and another over southeast NE/northeast KS. A
    seasonably rich/moist low-level airmass exists to the south of a
    front extending between these two lows, with surface dewpoints
    already in the low to mid 60s across much of the southern/central
    Plains to the east of a dryline. Both the dryline in the
    southern/central Plains and developing warm front in the
    Midwest/southern Great Lakes will likely serve as foci for intense thunderstorms this afternoon and evening, including the potential
    for several supercells.

    ...Midwest/Ohio Valley/Great Lakes...
    A complex scenario for severe thunderstorms remains apparent across
    the Midwest/OH Valley into the southern Great Lakes today, with
    multiple outflow boundaries from earlier convection rendering
    greater than usual uncertainty with the southward extent of possible thunderstorm development in IL/IN/OH. In general, continued
    low-level warm advection from the central Plains into the Midwest/OH
    Valley will support a moistening/destabilizing airmass through the
    afternoon as a northern-stream shortwave trough moves eastward
    across the Upper Midwest. A surface warm front will extend
    northeastward from a weak surface low in IA across southern WI and
    Lower MI. It still appears likely that multiple intense supercells
    will develop by 20-21Z along/near this boundary in IA/southern
    WI/northern IL in a very favorable airmass for significant severe
    hail given strong deep-layer shear and the presence of steep
    mid-level lapse rates. Low-level shear is expected to gradually
    strengthen through the evening in tandem with a modestly increasing south-southwesterly low-level jet.

    Any supercells than can remain on the warm/south side of the front
    will be capable of producing tornadoes, a few of which could be
    strong (EF-2/3). Some consideration was given to including greater
    tornado probabilities and a Moderate Risk (level 4 of 5) focused
    across southern WI/far northern IL. But, convection may have a
    tendency to grow upscale fairly quickly this evening, so confidence
    was not high enough for a categorical upgrade at this time.
    Regardless, very large to giant hail (potentially up to 3-4 inches
    in diameter) will be a threat with sustained supercells, and a swath
    of severe/damaging winds appears likely with a convective cluster
    spreading eastward across southern Lower MI this evening into
    tonight.

    A somewhat separate area of severe potential should also exist
    farther south across central IL into IN/OH this afternoon and
    evening. Greater low-level moisture and related instability are
    expected to exist across these areas compared to locations farther
    north. While large-scale forcing should remain fairly weak/nebulous
    across this region, a remnant outflow boundary may provide a focus
    for supercell development across central IL into IN by 20-21Z. Have
    expanded the Slight Risk for large hail, damaging winds, and perhaps
    a few tornadoes southward across these areas to account for this
    still somewhat uncertain potential.

    ...Southern/Central Plains...
    12Z observed soundings from DRT/MAF/FWD/OUN/TOP show the presence of
    steep mid-level lapse rates atop rich low-level moisture (generally
    14-15 g/kg mean mixing ratios) along/east of the surface dryline.
    Southwesterly mid-level flow and modest ascent preceding the upper
    trough over the Southwest/southern Rockies will gradually overspread
    the warm sector by mid to late afternoon. Moderate to strong
    instability (MLCAPE around 2000-3000 J/kg, locally stronger
    possible) and 35-45 kt of deep-layer shear will support multiple
    intense supercells. Explosive convective initiation across parts of
    western OK into south-central/southeast KS is expected by 20-21Z as
    lingering MLCIN erodes with filtered daytime heating and as
    convective temperatures are breached.

    The overall thermodynamic and kinematic environment appears quite
    favorable for very large to potentially giant hail (up to 3-4 inches
    in diameter) with any supercells that spread east-northeastward
    through the afternoon/evening. A gradually strengthening low-level
    jet across OK/KS by 00Z will also support a threat for a few
    tornadoes, a couple of which could be strong as low-level hodographs
    become enlarged. Gradual upscale growth/clustering should occur with
    time through the evening, with some risk for severe/damaging winds.
    The Enhanced Risk has been expanded a bit northeastward into south-central/southeast KS for a focused severe wind corridor.
    Farther south along the length of the dryline in TX, isolated to
    scattered supercells may develop this afternoon and evening, with a
    risk for mainly large to very large hail and occasional severe
    gusts.

    ...Northeast...
    Ongoing convection across southern Ontario and the Lower Great Lakes
    will continue to track eastward this afternoon into NY and parts of
    New England in tandem with a low-amplitude shortwave trough. Gradual
    clearing of low/mid-level clouds has already encouraged surface
    temperatures to warm into the 70s along/south of west-east oriented
    front. Thunderstorms are expected to gradually increase in coverage
    and intensity as weak to locally moderate instability and strong
    deep-layer shear support organized updrafts, including the potential
    for some supercells initially. The greatest severe risk will
    probably be scattered damaging winds given a tendency for convection
    to consolidate into one or more clusters. But, an isolated severe
    hail threat may exist with any sustained supercell, along with some
    chance for a tornado or two near the front where low-level shear
    will be locally enhanced.

    $$

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  • From COD Weather Processor@1:2320/107 to wx-storm@lists.illinois.edu on Wednesday, April 15, 2026 00:56:31
    ACUS01 KWNS 150056
    SWODY1
    SPC AC 150054

    Day 1 Convective Outlook
    NWS Storm Prediction Center Norman OK
    0754 PM CDT Tue Apr 14 2026

    Valid 150100Z - 151200Z

    ...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS ACROS PORTIONS
    OF THE GREAT LAKES REGION...

    ...SUMMARY...
    Severe thunderstorms are expected through tonight from the southern
    Plains into the Midwest. Large hail, several tornadoes (some
    strong), and swaths of severe/damaging gusts are all likely,
    particularly from eastern Iowa into the southern Great Lakes.

    ...Synopsis...
    Scattered discrete/semi-discrete supercells are ongoing across
    eastern Iowa, far northern Illinois, and southern Wisconsin along a
    diffuse warm frontal zone stretching eastward from weak surface low
    analyzed over eastern NE/western IA. The primary severe risk through
    the overnight hours will be associated with this activity as it
    spreads southeast through early morning. Further south across the central/southern Plains, poorly organized convection casts
    uncertainty in the nocturnal severe threat; however, a favorable
    environment will remain in place through Wednesday morning and could
    support severe convection.

    ...Midwest/Great Lakes...
    01 UTC regional radar mosaics show semi-discrete supercells ongoing
    across far eastern IA, northern IL, and southern WI with the early
    stages of upscale growth evident as storms interactions increase.
    This trend will continue through the overnight hours as this
    activity propagates east/southeast into lower MI and northern IN.
    The recent 00z DVN RAOB sampled a convective environment highly
    favorable for organized convection, which will maintain the
    potential for significant hail and tornadoes in the near term (most
    likely through 03 UTC) before a full transition to a linear mode
    takes place. Once this transition occurs, severe winds (including
    the potential for significant gusts in excess of 75 mph) and
    embedded circulations appear probable for areas downstream.

    ...Southern Iowa into Kansas...
    Thunderstorm development along a southward sagging cold front is
    anticipated in the coming hours across northeast KS into southern
    IA. Regional soundings sampled adequate buoyancy and strong
    deep-layer wind shear (around 50 knots) that will likely support
    organized convection along the front for a few hours. Storm motions
    along the boundary may foster clustering/upscale growth, but a
    severe wind, hail, and perhaps tornado threat is expected to
    materialize through the night.

    ...Oklahoma into Texas...
    Convective evolution thus far across western OK into northwest TX
    has been relatively lackluster given the otherwise buoyant and
    strongly sheared environment sampled by the 00z OUN sounding. This
    is likely due to expansive convective outflows resulting in
    undercutting and clustered storm modes as well as the presence of a
    subsidence inversion (also noted in the 00z sounding). It remains
    unclear whether or not this activity will be able to re-intensify
    through the late evening hours given. However, strengthening flow
    fields through 06 UTC may support some degree of improved
    organization and a more robust severe threat. This potential is
    hinted by recent HRRR solutions, but overall confidence is limited.
    Based on these trends, opted to remove the 30% hail/wind
    probabilities given low confidence in severe coverage. Further south
    into western TX, attempts at sustained convection have been noted
    over the past hour along the dryline, but downstream inhibition may
    limit overall storm coverage.

    ..Moore.. 04/15/2026

    $$

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  • From COD Weather Processor@1:2320/107 to wx-storm@lists.illinois.edu on Wednesday, April 15, 2026 05:55:05
    ACUS01 KWNS 150554
    SWODY1
    SPC AC 150553

    Day 1 Convective Outlook
    NWS Storm Prediction Center Norman OK
    1253 AM CDT Wed Apr 15 2026

    Valid 151200Z - 161200Z

    ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS THE
    SOUTHERN PLAINS...MIDWEST...AND INTO THE GREAT LAKES...

    ...SUMMARY...
    Severe thunderstorms posing a risk for large hail, strong wind
    gusts, and a couple of tornadoes will be possible across portions of
    the southern Plains toward the Great Lakes this afternoon and
    evening.

    ...Synopsis...
    A migratory upper-level wave is evident in water-vapor imagery over
    northern Mexico. This feature will lift northeastward into the
    Plains through the day, resulting in the eastward progression of a
    modest surface cyclone from the central High Plains into eastern NE
    by late afternoon. A broad, uncapped, and moderately sheared warm
    sector will be in place from the southern Plains into the mid-MS
    Valley and eastward into the Great Lakes/OH Valley. Strong to severe thunderstorm development appears probable across much of this warm
    sector, whether induced by ascent ahead of the primary upper wave or
    by localized mesoscale boundaries.

    ...Iowa and northern Missouri...
    Thunderstorm development appears likely by late afternoon from
    central IA into northern MO in the vicinity of the surface low.
    Stronger mid-level height falls compared to previous days lends
    higher confidence in thunderstorm development, and 50-60 knot 500 mb
    flow overspreading much of the warm sector will support organized
    convection, including the potential for splitting supercells capable
    of very large hail and tornadoes across IA and northern MO. A
    focused zone of higher tornado potential may emerge roughly along
    the I-80 corridor where backed low-level winds along the effective
    warm front will locally augment SRH and could support a strong
    tornado. HREF/REFS guidance both show the strongest UH signals
    across this zone, warranting higher (5%) tornado probabilities.

    ...Ozarks into Oklahoma and north Texas...
    Further south, initially discrete cells are anticipated along the
    dryline from southeast KS into OK and north TX by mid-afternoon.
    Despite somewhat higher confidence in storm development compared to
    previous days, mean flow vectors along the boundary may promote
    clustering and upscale growth within a few hours after initiation.
    This scenario appears to be reflected in recent HREF/REFS guidance
    in the form of numerous, but weak, UH streaks, as well as in
    deterministic CAM solutions that depict one or more convective bands
    emerging by early evening. Additionally, guidance hints at the
    potential for morning convection across parts of OK and the Ozark
    Plateau. It remains unclear what influence - if any- this activity
    will have on the southern Plains warm sector or if any outflow
    boundaries can emerge and focus a higher severe threat along
    mesoscale corridors. Given these uncertainties, all severe
    probabilities were expanded to account for the fairly wide envelope
    of potential outcomes, most of which will likely feature the
    potential for severe hail, wind, and tornadoes.

    ...Great Lakes into New England...
    The combination of low to mid-60s dewpoints and the eastward
    advection of an EML will support MLCAPE values upwards of 1000-1500
    J/kg across much of the Great Lakes region with gradually
    diminishing buoyancy with eastward extent towards the New England
    coast. Aloft, 40-50 knot westerly mid-level winds will remain in
    place within the crest of a modest ridge, establishing a zonal
    corridor of a buoyant and moderately sheared environment. It appears
    likely that multiple outflow boundaries and/or mid-level
    perturbations associated with upstream MCSs across MI, AR, and IA
    will likely reside within the warm sector by peak heating.
    Thunderstorm development along or in the vicinity of these features
    will support multiple corridors of strong to severe convection. This
    scenario is depicted by most recent CAMs, which show multiple
    convection bands traversing the warm sector through early evening.
    However, exactly where these bands will become established (and
    where corridors of higher severe potential will emerge) remains
    uncertain given variance in recent guidance.

    ..Moore/Wendt.. 04/15/2026

    $$

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  • From COD Weather Processor@1:2320/107 to wx-storm@lists.illinois.edu on Wednesday, April 15, 2026 12:47:23
    ACUS01 KWNS 151247
    SWODY1
    SPC AC 151246

    Day 1 Convective Outlook
    NWS Storm Prediction Center Norman OK
    0746 AM CDT Wed Apr 15 2026

    Valid 151300Z - 161200Z

    ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FROM THE SOUTHERN
    PLAINS INTO THE MIDWEST AND SOUTHERN GREAT LAKES...

    ...SUMMARY...
    Severe thunderstorms posing a risk for large hail to very large
    hail, severe gusts, and a couple of tornadoes will be possible
    across portions of the southern Plains toward the Great Lakes this
    afternoon and evening.

    ...Synopsis...
    Water-vapor imagery this morning shows an upper trough from the
    eastern Dakotas south-southwestward into the southern Rockies. A
    few disturbances will migrate eastward coincident with the trough
    with the most notable being over the central High Plains this
    morning. The aforementioned disturbance will move east reaching the
    mid-upper MS Valley with the trailing southern extent of the wave
    moving into the MO Ozarks and OK by daybreak Thursday. A weak
    diffuse low will move from northern KS to the southwest Great Lakes
    by late tonight. Farther east, an MCV near MO-IL will translate
    east and become perhaps a focus for storm activity later this
    afternoon across OH-PA. A rather complex forecast is apparent due
    in large part to considerable convection and related outflow
    permeating the warm sector overnight across much of the Slight-Risk
    area.

    ...Iowa into the mid MS Valley...
    In the wake of showers/storms this morning from IA southward into
    MO, a moist and weakly capped airmass will destabilize through early
    afternoon. The eastward approach of the mid-level disturbance will
    likely contribute towards scattered thunderstorms developing 19-21z
    from near the weak low eastward along the composite outflow/frontal
    zone into IL-WI and southward into MO within a weakly capped warm
    sector. Forecast soundings show straight-line hodographs over IA
    with sizable CAPE in the hail growth zone. The potential for
    splitting supercells appears evident with the stronger storms
    capable of very large hail and perhaps some tornado risk across IA
    and northern MO.

    ...Ozarks into Oklahoma and north Texas...
    Morning raobs showed steep 700-500 mb lapse rates (7.5-8 deg C/km)
    atop a seasonably very moist return-flow airmass. Models generally
    show storm development near the dryline by mid afternoon with
    initial development becoming supercellular. Large to very large
    hail will be possible with the stronger updrafts. Residual outflow
    from overnight convection moving into the Ozarks may play a role in
    enhancing low-level shear later today. Forecast soundings show
    somewhat limited low-level hodographs with a tendency for a
    veer-back-veer signature. Additional storms will favor some
    clustering and upscale growth with time due in part to the forecast
    hodographs. Nonetheless, all hazards will be possible at least
    through the early convective life cycle before the possibility for
    wind damage and linear structures perhaps evolve during the evening.

    ...Southern Great Lakes into the Northeast...
    The remnants of an overnight squall line are moving east across
    NY-PA this morning with a trailing outflow boundary extending
    westward into OH and northeast IN. Moist low levels and the
    eastward advection of steeper mid-level lapse rates will act to
    destabilize the southern Great Lakes into western PA through midday
    and into the afternoon. Forcing for ascent and enhancement of flow
    associated with the MCV will potentially focus thunderstorms and aid
    in their organization potential beginning this afternoon.
    Considerable uncertainty remains regarding this scenario and whether
    a mesoscale corridor of higher tornado probabilities is needed
    (i.e., northeast OH). Will defer to later outlooks to where perhaps
    mesoscale corridors of greater wind/hail threat and an isolated risk
    for a couple of tornadoes could develop.

    ..Smith/Dean.. 04/15/2026

    $$

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  • From COD Weather Processor@1:2320/107 to wx-storm@lists.illinois.edu on Wednesday, April 15, 2026 16:32:28
    ACUS01 KWNS 151632
    SWODY1
    SPC AC 151630

    Day 1 Convective Outlook
    NWS Storm Prediction Center Norman OK
    1130 AM CDT Wed Apr 15 2026

    Valid 151630Z - 161200Z

    ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF
    THE SOUTHERN/CENTRAL PLAINS INTO THE MIDWEST/OHIO VALLEY AND
    SOUTHERN GREAT LAKES...

    ...SUMMARY...
    Severe thunderstorms posing a risk for large to very large hail,
    damaging winds, and perhaps a few tornadoes will be possible across
    parts of the southern/central Plains into the Midwest/Ohio Valley
    and southern Great Lakes this afternoon and evening.

    ...Synopsis...
    Severe potential across the broad warm sector will be complicated by
    ongoing thunderstorms/MCVs and associated cloud cover. A neutral to
    positively tilted upper trough will eject northeastward across the southern/central Plains today, with a broad zone of enhanced
    mid-level southwesterly winds extending over much of TX/OK into the
    Midwest/OH Valley and Great Lakes. At the surface, a weak low over
    southeast NE late this morning is forecast to develop slowly
    northeastward across IA through the afternoon and evening, with a quasi-stationary front extending northeastward from this low towards
    southern WI/Lower MI. A dryline extends southward across KS/OK into
    west TX. Multiple MCVs related to ongoing/earlier convection are
    also noted in recent visible satellite/radar imagery, and these
    features may aid additional convective development this afternoon.

    ...Iowa into Missouri...
    Forcing for ascent associated with the ejecting upper trough will
    overspread the front draped across IA this afternoon. Ongoing
    supercell in western IA and cloudiness near the front late this
    morning cast some uncertainty on the degree of destabilization that
    will occur this afternoon, and the overall intensity of convection.
    Still, expectations are for additional robust thunderstorms to
    eventually develop by 19-21Z along/near the front in IA, with steep
    mid-level lapse rates noted on the observed 12Z TOP sounding
    supporting moderate to locally strong MLCAPE even if
    clouds/precipitation hinder daytime heating to some extent. Various
    NAM/RAP forecast soundings show elongated/nearly straight hodographs
    at mid/upper levels and 50+ kt of deep-layer shear, which will be
    favorable for upper-level/anvil venting and hail production with any
    supercells that form. Large to very large hail will be a concern
    with initially discrete convection. But, some tendency for
    clustering and movement north of the surface front casts
    considerable uncertainty on the wind/tornado potential. Even so,
    some chance for a few tornadoes and scattered damaging winds may
    exist along/south of the front across IA into MO with any convection
    that can develop east of the dryline.

    ...Southern Plains into the Ozarks and Mid Mississippi Valley...
    A seasonably moist low-level airmass remains in place across the
    southern Plains into the Ozarks and mid MS Valley, with observed 12Z
    soundings from FWD/OUN/SGF indicating mean mixing ratios ranging
    12-13.6 g/kg. However, even with steep mid-level lapse rates noted
    across TX/OK, profiles are fairly saturated at mid/upper levels, and
    plentiful cloud cover is present in recent visible satellite imagery
    across these regions. It still appears likely that surface-based
    thunderstorms will develop this afternoon (around 19-21Z) along/east
    of the dryline as MLCIN gradually erodes ahead of the ejecting upper
    trough. But, overall evolution remains somewhat unclear, with
    potential for messy storm modes/interactions fairly early in the
    convective life cycle given a large degree of boundary-parallel flow
    in low/mid levels. Initial supercells should pose a threat for
    mainly large to very large hail (isolated 2+ inches in diameter),
    before clustering and an increase in damaging wind potential occurs.
    The tornado threat is less clear, as stronger low-level flow will
    tend to remain focused farther north into the Midwest. Still,
    sufficient low-level shear should exist this afternoon and evening
    to support a threat for a few tornadoes with both supercells and
    embedded within clusters.

    ...Midwest/Ohio Valley into Western Pennsylvania...
    An MCV evident over eastern IL/western IN will continue to track
    eastward into northern IN and eventually OH this afternoon and
    evening. Ongoing thunderstorms associated with this MCV have
    remained sub-severe through much of the morning. But, gradual
    destabilization of the already moist low-level airmass downstream
    should support some uptick in convective coverage and intensity
    across the OH Valley by mid to late afternoon. Localized enhancement
    to the west-southwesterly low-level winds should focus across parts
    of northern OH and vicinity, where somewhat greater low-level shear
    and tornado potential may exist. Strong deep-layer shear will easily
    support organized convection, including the potential for supercells
    with a threat for large hail, damaging winds, and perhaps a couple
    of tornadoes. Additional thunderstorms may eventually develop
    eastward from the mid MS Valley into IL/IN in association with
    another MCV. Large hail, damaging winds, and a tornado or two may
    also occur with this activity, if it develops.

    ..Gleason/Squitieri.. 04/15/2026

    $$

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  • From COD Weather Processor@1:2320/107 to wx-storm@lists.illinois.edu on Wednesday, April 15, 2026 19:57:30
    ACUS01 KWNS 151957
    SWODY1
    SPC AC 151955

    Day 1 Convective Outlook
    NWS Storm Prediction Center Norman OK
    0255 PM CDT Wed Apr 15 2026

    Valid 152000Z - 161200Z

    ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS PARTS OF THE
    SOUTHERN/CENTRAL PLAINS INTO THE MIDWEST/OHIO VALLEY AND SOUTHERN
    GREAT LAKES...

    ...SUMMARY...
    Severe thunderstorms posing a risk for large to very large hail,
    damaging winds, and perhaps a few tornadoes will be possible across
    parts of the southern/central Plains into the Midwest/Ohio Valley
    and southern Great Lakes this afternoon and evening.

    ...20Z Update...

    ...Mid MS Valley through the Ozarks into the Southern Plains...
    Recent surface analysis places a low in the NE/IA/MO border
    intersection vicinity, with a dry line extending southwestward from
    this low through eastern KS, western OK, and northwest TX. As
    mentioned in MCD #448, the elevated supercell ongoing across central
    IA could begin to interact with an environment more supportive of
    surface-based storms. If a transition to surface-based is realized,
    an increased potential for damaging gusts and a tornado will exist.
    New development is also beginning across central IA, along the
    outflow extending southwestward for this supercell. Hail remains the
    primary risk across the region, both with the ongoing supercell and
    any new development along its outflow.

    Increasing thunderstorm coverage is still expected tonight along the
    dryline as it shifts eastward, beginning across northwest TX and
    central OK now before expanding northward into MO, and potentially southwestward into more of southwest TX later. Large hail remains
    the primary threat with this initially more cellular activity. Some
    very large hail (i.e. 2"+ in diameter) is possible. Over time,
    storm interactions and/or upscale growth is anticipated, with a
    trend towards a threat for more damaging gusts. Tornado threat
    remains low, largely due weakness in the low to mid-level flow and
    convective mode issues. However, some modest strengthening of the
    low-level flow should exist this afternoon and evening from eastern
    OK into the mid MS Valley, supporting a threat for a few tornadoes
    with both supercells and embedded within clusters.

    ...OH Valley...
    Severe Thunderstorm Watch #120 is currently ongoing from far
    southeast Lower MI across northern OH into far northwest PA. Here, a
    mix of clusters and supercells pose a threat for scattered damaging
    winds and large hail as they spread quickly east-northeastward this
    afternoon and evening. A tornado or two is also possible.

    ..Mosier.. 04/15/2026

    .PREV DISCUSSION... /ISSUED 1130 AM CDT Wed Apr 15 2026/

    ...Synopsis...
    Severe potential across the broad warm sector will be complicated by
    ongoing thunderstorms/MCVs and associated cloud cover. A neutral to
    positively tilted upper trough will eject northeastward across the southern/central Plains today, with a broad zone of enhanced
    mid-level southwesterly winds extending over much of TX/OK into the
    Midwest/OH Valley and Great Lakes. At the surface, a weak low over
    southeast NE late this morning is forecast to develop slowly
    northeastward across IA through the afternoon and evening, with a quasi-stationary front extending northeastward from this low towards
    southern WI/Lower MI. A dryline extends southward across KS/OK into
    west TX. Multiple MCVs related to ongoing/earlier convection are
    also noted in recent visible satellite/radar imagery, and these
    features may aid additional convective development this afternoon.

    ...Iowa into Missouri...
    Forcing for ascent associated with the ejecting upper trough will
    overspread the front draped across IA this afternoon. Ongoing
    supercell in western IA and cloudiness near the front late this
    morning cast some uncertainty on the degree of destabilization that
    will occur this afternoon, and the overall intensity of convection.
    Still, expectations are for additional robust thunderstorms to
    eventually develop by 19-21Z along/near the front in IA, with steep
    mid-level lapse rates noted on the observed 12Z TOP sounding
    supporting moderate to locally strong MLCAPE even if
    clouds/precipitation hinder daytime heating to some extent. Various
    NAM/RAP forecast soundings show elongated/nearly straight hodographs
    at mid/upper levels and 50+ kt of deep-layer shear, which will be
    favorable for upper-level/anvil venting and hail production with any
    supercells that form. Large to very large hail will be a concern
    with initially discrete convection. But, some tendency for
    clustering and movement north of the surface front casts
    considerable uncertainty on the wind/tornado potential. Even so,
    some chance for a few tornadoes and scattered damaging winds may
    exist along/south of the front across IA into MO with any convection
    that can develop east of the dryline.

    ...Southern Plains into the Ozarks and Mid Mississippi Valley...
    A seasonably moist low-level airmass remains in place across the
    southern Plains into the Ozarks and mid MS Valley, with observed 12Z
    soundings from FWD/OUN/SGF indicating mean mixing ratios ranging
    12-13.6 g/kg. However, even with steep mid-level lapse rates noted
    across TX/OK, profiles are fairly saturated at mid/upper levels, and
    plentiful cloud cover is present in recent visible satellite imagery
    across these regions. It still appears likely that surface-based
    thunderstorms will develop this afternoon (around 19-21Z) along/east
    of the dryline as MLCIN gradually erodes ahead of the ejecting upper
    trough. But, overall evolution remains somewhat unclear, with
    potential for messy storm modes/interactions fairly early in the
    convective life cycle given a large degree of boundary-parallel flow
    in low/mid levels. Initial supercells should pose a threat for
    mainly large to very large hail (isolated 2+ inches in diameter),
    before clustering and an increase in damaging wind potential occurs.
    The tornado threat is less clear, as stronger low-level flow will
    tend to remain focused farther north into the Midwest. Still,
    sufficient low-level shear should exist this afternoon and evening
    to support a threat for a few tornadoes with both supercells and
    embedded within clusters.

    ...Midwest/Ohio Valley into Western Pennsylvania...
    An MCV evident over eastern IL/western IN will continue to track
    eastward into northern IN and eventually OH this afternoon and
    evening. Ongoing thunderstorms associated with this MCV have
    remained sub-severe through much of the morning. But, gradual
    destabilization of the already moist low-level airmass downstream
    should support some uptick in convective coverage and intensity
    across the OH Valley by mid to late afternoon. Localized enhancement
    to the west-southwesterly low-level winds should focus across parts
    of northern OH and vicinity, where somewhat greater low-level shear
    and tornado potential may exist. Strong deep-layer shear will easily
    support organized convection, including the potential for supercells
    with a threat for large hail, damaging winds, and perhaps a couple
    of tornadoes. Additional thunderstorms may eventually develop
    eastward from the mid MS Valley into IL/IN in association with
    another MCV. Large hail, damaging winds, and a tornado or two may
    also occur with this activity, if it develops.

    $$

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  • From COD Weather Processor@1:2320/107 to wx-storm@lists.illinois.edu on Thursday, April 16, 2026 00:59:03
    ACUS01 KWNS 160058
    SWODY1
    SPC AC 160057

    Day 1 Convective Outlook
    NWS Storm Prediction Center Norman OK
    0757 PM CDT Wed Apr 15 2026

    Valid 160100Z - 161200Z

    ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS THIS EVENING IN A
    CORRIDOR FROM THE SOUTHEASTERN GREAT PLAINS THROUGH THE MIDWEST...

    ...SUMMARY...
    Potential for damaging wind gusts could still increase a bit with
    developing clusters of storms through mid to late evening across
    parts of the Midwest into the southeastern Great Plains, while also
    continuing with another cluster of storms spreading across northern
    portions of the Allegheny Plateau.

    ...01Z Update...
    Mid-level ridging centered near the south Atlantic Seaboard remains
    prominent, but is undergoing some suppression as at least a couple
    of short wave troughs migrate around its western through northern
    periphery. The most substantive of these waves is forecast to
    continue migrating northeast of the lower Missouri Valley through Wisconsin/Illinois by late tonight, accompanied by a modest
    downstream surface frontal wave. A vigorous jet streak associated
    with one or two lower amplitude downstream perturbations is forecast
    to propagate from the lee of the lower Great Lakes through southern
    New England. It appears that mid/upper troughing with embedded
    low-amplitude perturbations will linger across parts of the southern
    Great Plains.

    Peak afternoon destabilization along the dryline, from near its
    frontal intersection (roughly near/north of the Greater Kansas City
    area) southwestward into the Texas South Plains, is already waning.
    However, it appears that at least a narrow corridor of moderate
    residual boundary-layer instability in the warm sector to its east
    could may maintain vigorous convection and support continuing
    upscale convective growth into mid/late evening across parts of
    southeastern Oklahoma, western/northern Arkansas, central/eastern
    Missouri and central/northern Illinois. As this occurs, largely
    coincident with a northeastward propagating 30-40 kt southwesterly
    850 mb jet, this may be accompanied by developing areas of
    increasing potential for damaging wind gusts and perhaps a few brief
    tornadoes, before convection weakens overnight.

    ..Kerr.. 04/16/2026

    $$

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  • From COD Weather Processor@1:2320/107 to wx-storm@lists.illinois.edu on Thursday, April 16, 2026 06:01:35
    ACUS01 KWNS 160601
    SWODY1
    SPC AC 160559

    Day 1 Convective Outlook
    NWS Storm Prediction Center Norman OK
    1259 AM CDT Thu Apr 16 2026

    Valid 161200Z - 171200Z

    ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS THIS AFTERNOON
    ACROSS PARTS OF WESTERN AND CENTRAL NEW YORK INTO SOUTHERN
    VERMONT...

    ...SUMMARY...
    A few severe thunderstorms are possible this afternoon in a corridor
    across western through central New York (state) and adjacent
    southern Vermont.

    ...Discussion...
    A significant mid-level trough and embedded low now digging across
    the Pacific Northwest is forecast to split as it continues inland
    through this period. One perturbation, perhaps including a
    continuing cyclonic circulation, is forecast to turn eastward across
    the northern Rockies through the central Canadian/U.S. border area.
    Another perturbation is forecast to dig southeastward across the
    Great Basin into early Friday. It appears that the larger-scale
    evolving troughing will be preceded by a significant cold frontal
    surge to the lee of the northern U.S. Rockies, through much of the
    northern and central Great Plains by 12Z Friday.

    Downstream, initially prominent mid-level ridging centered near the
    southern Atlantic Seaboard is forecast to become increasingly
    suppressed, as one short wave trough, approaching southwestern
    portions of the Great Lakes region early today, turns eastward then southeastward across the lower Great Lakes vicinity into northern
    Mid Atlantic. It appears that this will be trailed by another
    perturbation, which is forecast to progress east of the Ozark
    Plateau through the lower Ohio and Tennessee Valleys, before digging
    across the southern Appalachians, downstream of short wave ridging
    building across and east of the mid/upper Mississippi Valley.

    ...Mid South into lower Great Lakes and Northeast...
    The primary and trailing short wave troughs advancing to the east of
    the Mississippi Valley are forecast to be preceded by the remnants
    of overnight convection across parts of the lower Great Lakes, Ohio
    Valley, and Mid South at the outset of the period. The impacts of
    associated cloud cover and outflow on destabilization within the
    warm sector of a broad, but weak, surface low migrating northeast of
    the lower Great Lakes during the day remain unclear. However,
    various model output, including convection allowing guidance,
    suggest that destabilization and strengthening shear along a warm
    frontal zone (as it strengthens with differential heating) may
    become a focus for organized strong thunderstorm development across
    New York state by afternoon. It appears that this may include an
    evolving cluster, perhaps preceded by more discrete thunderstorm
    activity, in an environment conducive to evolving supercell
    structures, with potential to produce severe hail, wind and a risk
    for a couple of tornadoes.

    Additional thunderstorm activity may eventually develop and
    strengthen, accompanied by at least a risk for strong to severe wind
    gusts by late afternoon, in a corridor of stronger daytime heating
    ahead of a developing cold front spreading into the upper Ohio
    Valley/Allegheny and Cumberland Plateau by late afternoon.

    There is not a well-defined signal in the latest model output, but a
    corridor of differential surface heating along weakening trailing
    convective outflow across the Mid South vicinity could become a
    focus for supercell development. It currently appears that this
    potential could peak across north central into northeastern Arkansas
    by late this afternoon, aided by moderate boundary-layer
    destabilization and stronger mid-level forcing for ascent associated
    with a cyclonic vorticity center migrating across the region.

    ...Southern Great Plains...
    Moderate to strong potential instability is forecast to develop
    beneath steep lapse rates, along and east of a dryline which likely
    will be retreating westward across the high plains by early this
    evening. While this will be conditionally support of severe
    thunderstorm development, forcing to support initiation of sustained thunderstorms remains unclear, associated from, perhaps, the higher
    terrain near/east of the Texas Big Bend. Beneath moderate to strong southwesterly mid/upper flow, this could include an isolated
    supercell or two which could propagate across the Rio Grande River,
    before weakening in the presence of increasing inhibition this
    evening.

    ..Kerr/Lyons.. 04/16/2026

    $$

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  • From COD Weather Processor@1:2320/107 to wx-storm@lists.illinois.edu on Thursday, April 16, 2026 12:36:08
    ACUS01 KWNS 161236
    SWODY1
    SPC AC 161234

    Day 1 Convective Outlook
    NWS Storm Prediction Center Norman OK
    0734 AM CDT Thu Apr 16 2026

    Valid 161300Z - 171200Z

    ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FOR NEW YORK INTO
    SOUTHERN VERMONT AND OVER THE NORTHERN HALF OF ARKANSAS...

    ...SUMMARY...
    Scattered severe thunderstorms are possible this afternoon over New
    York into southern Vermont with damaging gusts and perhaps a tornado
    or two the primary threats. Large to very large hail is possible
    with stronger storms over the northern half of Arkansas.

    ...Northeast southward into the central Appalachians and Cumberland
    Plateau...
    Water-vapor imagery this morning shows an upper trough over the
    mid/upper MS Valley moving east towards the Northeast. A belt of
    strong west-southwesterly 500-mb flow (50-65 kt) will overspread
    much of the Northeast today in conjunction with the
    eastward-migrating shortwave trough. Visible-satellite imagery
    shows scattered to broken cloud cover to the south of a west-east
    oriented frontal zone extending east from a surface low analyzed
    over Lake Huron. Heating of an adequately moist boundary layer
    (surface dewpoints in the 56-62 deg F range) will result in weak to
    locally moderate buoyancy by midday into the mid afternoon (500-1250
    J/kg MLCAPE). Large-scale ascent associated with the approaching
    disturbance and convergence in the vicinity of the frontal zone will
    lead to scattered storm development this afternoon. Ample mid to
    high-level flow will favor storm organization, including the
    possibility for a few supercells and an organized band of storms. A
    risk for large hail and a tornado could accompany the more intense
    cells, whereas the wind risk will tend to focus with linear
    structures that evolve. An isolated threat for wind damage and
    perhaps hail will extend southward into PA/WV and the Cumberland
    Plateau, where a few stronger storms may yield those hazards.

    ...Mid South...
    Satellite imagery shows the trailing portion of the upper shortwave
    trough over the western Great Lakes is moving east across OK this
    morning. This upper feature and associated mid-level cold pocket
    (-16 to -18 deg C at 500 mb) will move across the MO Ozarks and AR
    this afternoon. A reservoir of lower 60s deg F surface dewpoints
    and strong heating in wake of early day showers and isolated
    thunderstorms will favor robust CAPE profiles and elongated mid to
    upper portions of the hodograph. Latest guidance shows several
    cells developing within a weakly capped airmass by mid afternoon.
    The stronger storms will likely become supercells yielding a risk
    for large to very large hail (1 to 3 inches in diameter). Modest
    low-level flow will tend to limit low-level mesocyclone intensity
    and the lessen the overall tornado risk. A couple of smaller
    clusters may evolve during the early evening with an isolated wind
    threat potentially ensuing before this activity weakens by mid
    evening.

    ...Edwards Plateau into the TX Big Country and western north TX...
    Moderate to strong potential instability is forecast to develop
    beneath steep lapse rates, along and east of a dryline. Although
    neutral to weak shortwave ridging is expected today, some of the
    latest model guidance shows isolated to widely scattered storm
    development by late afternoon on the northwestern rim of richer
    low-level moisture arcing from the Edwards Plateau into western
    north TX. Strong heating will likely erode appreciable remaining
    convective inhibition by 20-22 UTC. Strong west-southwesterly
    100-kt 200-mb flow will elongate hodographs amidst a moderately
    buoyant airmass. Widely spaced/isolated supercells will mainly
    yield a large hail threat late this afternoon into the early
    evening.

    ..Smith/Dean.. 04/16/2026

    $$

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  • From COD Weather Processor@1:2320/107 to wx-storm@lists.illinois.edu on Thursday, April 16, 2026 16:26:41
    ACUS01 KWNS 161626
    SWODY1
    SPC AC 161624

    Day 1 Convective Outlook
    NWS Storm Prediction Center Norman OK
    1124 AM CDT Thu Apr 16 2026

    Valid 161630Z - 171200Z

    ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FOR NEW YORK INTO
    SOUTHERN VERMONT AS WELL AS FOR NORTHERN ARKANSAS...SOUTHERN
    MISSOURI AND FAR WESTERN TENNESSEE...

    ...SUMMARY...
    Scattered severe thunderstorms are possible this afternoon over New
    York into southern Vermont with damaging gusts and perhaps a tornado
    or two the primary threats. Large to very large hail is possible
    with stronger storms over the northern half of Arkansas.

    ...Ozark Plateau into the Mid-South...
    Recent visible satellite imagery shows some ACCAS across
    south-central MO, indicative of low/mid-level warm advection amid
    the steep lapse rate environment in place. These steep lapse rates
    are forecast to continue spread eastward, while low-level moisture
    advection brings low 60s dewpoints northeastward into the region as
    well. This will result in a moderate to strongly buoyant airmass
    (i.e. MLCAPE from 1500 to 2000 J/kg) by the early afternoon.
    Additionally, moderate mid to high level flow will remain in place,
    resulting in long hodographs and overall environmental conditions
    that are very favorable for supercells capable of large to very
    large hail. Latest guidance continues the earlier trends of
    developing storms in this area, which match observational
    expectations as well. Large to very large hail (1 to 3 inches in
    diameter) is possible with any updrafts that mature into supercells.
    Low-level flow is weak, keeping tornado probability low but none
    zero. Given the modest pocket of mid-level dry air present,
    supercells will likely become outflow dominant with time,
    supporting the potential for damaging gusts across the region
    (particular eastern areas) as well.

    ...NY/VT/NH southeastward into the central Appalachians...
    Recent surface analysis places a low over the eastern
    Ontario/southern Quebec border vicinity, with modest surface
    troughing extending southeastward from this low across central Lower
    MI. Airmass across much of NY is characterized by dewpoints in the
    low 60s. Dewpoints should stay in the low 60s throughout the day
    despite modest mixing amid diurnal heating. This should result in
    airmass destabilization ahead of the modest surface trough, with a
    general increase in large-scale ascent beginning during the
    afternoon as well. Little to no convective inhibition is
    anticipated, supporting the potential for more cellular development
    over the warm sector initially, before a more expansive convective
    line develops along the eastward-progressing surface trough. Ample
    mid to high-level flow will favor storm organization, including a
    risk for large hail and a tornado with the more intense discrete
    cells. The wind risk will tend to focus with linear structures that
    evolve over time. An isolated threat for wind damage and perhaps
    hail will extend southward into PA/WV and the Cumberland Plateau,
    where a few stronger storms may yield those hazards.

    ...Edwards Plateau into the TX Big Country and western north TX...
    A strongly buoyant and weakly capped airmass is expected to develop
    along the dryline extending southwestward from western OK through
    the Edwards Plateau. Although neutral to weak shortwave ridging is
    expected throughout much of the morning into the late afternoon,
    some limited ascent (associated with a weak shortwave trough moving
    out of northern Mexico) may begin to spread across the dryline by
    early evening. This combined with dryline circulations may be enough
    to initiate isolated to widely scattered thunderstorms. Low-level
    flow will be weak, but moderate to strong westerly flow aloft will
    result in wind profiles very favorable for supercells capable of
    large to very large hail. Any storms that develop should weaken
    quickly with the onset of nocturnal cooling.

    ..Mosier/Squitieri.. 04/16/2026

    $$

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  • From COD Weather Processor@1:2320/107 to wx-storm@lists.illinois.edu on Thursday, April 16, 2026 20:02:43
    ACUS01 KWNS 162002
    SWODY1
    SPC AC 162000

    Day 1 Convective Outlook
    NWS Storm Prediction Center Norman OK
    0300 PM CDT Thu Apr 16 2026

    Valid 162000Z - 171200Z

    ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS NEW YORK
    INTO SOUTHERN VERMONT...AND THE OZARKS INTO THE MID-SOUTH...

    ...SUMMARY...
    Scattered severe thunderstorms are possible this afternoon over New
    York into southern Vermont with damaging gusts and perhaps a tornado
    or two the primary threats. Very large hail and severe gusts are
    possible with the stronger storms over the Ozarks into the
    Mid-South.

    ...20Z Update...
    The SLGT in the Ozarks/Mid-South was expanded northward into central
    MO, where an isolated supercell with a risk of very large hail and
    damaging gusts has emerged along the northern periphery of a remnant
    cold pool. Farther south within Severe Thunderstorm Watch 127,
    several discrete/splitting supercells continue to pose a risk of
    very large hail (recent report of 2.75 inches) and locally damaging
    wind gusts. With time, this activity may congeal into a loosely
    organized cluster, with an increasing risk of damaging wind gusts.
    The MRGL risk was also expanded slightly westward into southwest OK,
    where boundary-layer cumulus is gradually deepening. Any isolated
    storms that can form here will pose a risk of large to very large
    hail and severe downbursts. Finally, the MRGL was expanded slightly
    westward in southwest TX toward Fort Stockton. While convective
    initiation is still in question here, deepening boundary-layer
    cumulus along the higher terrain could result in an isolated storm
    or two, with a risk of very large hail.

    ..Weinman.. 04/16/2026

    .PREV DISCUSSION... /ISSUED 1124 AM CDT Thu Apr 16 2026/

    ...Ozark Plateau into the Mid-South...
    Recent visible satellite imagery shows some ACCAS across
    south-central MO, indicative of low/mid-level warm advection amid
    the steep lapse rate environment in place. These steep lapse rates
    are forecast to continue spread eastward, while low-level moisture
    advection brings low 60s dewpoints northeastward into the region as
    well. This will result in a moderate to strongly buoyant airmass
    (i.e. MLCAPE from 1500 to 2000 J/kg) by the early afternoon.
    Additionally, moderate mid to high level flow will remain in place,
    resulting in long hodographs and overall environmental conditions
    that are very favorable for supercells capable of large to very
    large hail. Latest guidance continues the earlier trends of
    developing storms in this area, which match observational
    expectations as well. Large to very large hail (1 to 3 inches in
    diameter) is possible with any updrafts that mature into supercells.
    Low-level flow is weak, keeping tornado probability low but none
    zero. Given the modest pocket of mid-level dry air present,
    supercells will likely become outflow dominant with time,
    supporting the potential for damaging gusts across the region
    (particular eastern areas) as well.

    ...NY/VT/NH southeastward into the central Appalachians...
    Recent surface analysis places a low over the eastern
    Ontario/southern Quebec border vicinity, with modest surface
    troughing extending southeastward from this low across central Lower
    MI. Airmass across much of NY is characterized by dewpoints in the
    low 60s. Dewpoints should stay in the low 60s throughout the day
    despite modest mixing amid diurnal heating. This should result in
    airmass destabilization ahead of the modest surface trough, with a
    general increase in large-scale ascent beginning during the
    afternoon as well. Little to no convective inhibition is
    anticipated, supporting the potential for more cellular development
    over the warm sector initially, before a more expansive convective
    line develops along the eastward-progressing surface trough. Ample
    mid to high-level flow will favor storm organization, including a
    risk for large hail and a tornado with the more intense discrete
    cells. The wind risk will tend to focus with linear structures that
    evolve over time. An isolated threat for wind damage and perhaps
    hail will extend southward into PA/WV and the Cumberland Plateau,
    where a few stronger storms may yield those hazards.

    ...Edwards Plateau into the TX Big Country and western north TX...
    A strongly buoyant and weakly capped airmass is expected to develop
    along the dryline extending southwestward from western OK through
    the Edwards Plateau. Although neutral to weak shortwave ridging is
    expected throughout much of the morning into the late afternoon,
    some limited ascent (associated with a weak shortwave trough moving
    out of northern Mexico) may begin to spread across the dryline by
    early evening. This combined with dryline circulations may be enough
    to initiate isolated to widely scattered thunderstorms. Low-level
    flow will be weak, but moderate to strong westerly flow aloft will
    result in wind profiles very favorable for supercells capable of
    large to very large hail. Any storms that develop should weaken
    quickly with the onset of nocturnal cooling.

    $$

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  • From COD Weather Processor@1:2320/107 to wx-storm@lists.illinois.edu on Friday, April 17, 2026 01:01:12
    ACUS01 KWNS 170101
    SWODY1
    SPC AC 170059

    Day 1 Convective Outlook
    NWS Storm Prediction Center Norman OK
    0759 PM CDT Thu Apr 16 2026

    Valid 170100Z - 171200Z

    ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS THIS EVENING
    ACROSS PARTS OF EASTERN NEW YORK INTO WESTERN NEW ENGLAND...PARTS OF
    THE OZARK PLATEAU INTO MID SOUTH...AND THE PECOS VALLEY/RIO GRANDE
    VALLEY VICINITY...

    ...SUMMARY...
    Widely scattered areas of scattered strong to severe thunderstorm
    development are expected to generally wane through mid to late
    evening.

    ...01Z Update...

    ...Parts of Upstate New York into western New England...
    Forcing for ascent accompanying a weak frontal wave is maintaining
    an area of scattered stronger storms now overspreading areas to the
    northwest of Albany NY, in the presence of strong deep-layer shear.
    Instability sampled in the evening sounding from Albany is rather
    weak, but profiles might still be supportive of at least some risk
    for localized severe wind and hail into mid/late evening as forcing
    overspreads parts of southern Vermont, New Hampshire and adjacent
    Maine.

    ...Ozark Plateau into Mid South...
    The primary east-southeastward propagating organized storm cluster
    appears to be in the process of weakening, as southeasterly near
    surface updraft inflow across middle Tennessee becomes less
    unstable. However, renewed thunderstorm development persists along
    and to the cool side of the trailing convective outflow across the
    Missouri Bootheel vicinity, with additional attempts along a diffuse
    zone of differential surface heating extending westward across
    northern Arkansas. This is occurring beneath warming and more
    strongly capping lower/mid-tropospheric air, but given inflow of
    potentially sizable CAPE, in the presence of moderate westerly
    shear, there remains at least some risk for supercell development
    capable of producing large hail this evening.

    ...West Texas...
    Potential for sustained severe thunderstorm development appears low
    along the retreating dryline across parts of northwest Texas into
    the South Plains overnight.

    ..Kerr.. 04/17/2026

    $$

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  • From COD Weather Processor@1:2320/107 to wx-storm@lists.illinois.edu on Friday, April 17, 2026 06:02:18
    ACUS01 KWNS 170602
    SWODY1
    SPC AC 170600

    Day 1 Convective Outlook
    NWS Storm Prediction Center Norman OK
    0100 AM CDT Fri Apr 17 2026

    Valid 171200Z - 181200Z

    ...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS THIS AFTERNOON
    INTO TONIGHT ACROSS PARTS CENTRAL AND SOUTHWESTERN WISCONSIN...FAR
    SOUTHEASTERN MINNESOTA...EASTERN IOWA...MUCH OF NORTHERN AND CENTRAL
    ILLINOIS...NORTHERN AND CENTRAL MISSOURI...EASTERN AND SOUTHERN
    KANSAS...AND NORTHERN OKLAHOMA...

    ...SUMMARY...
    Widespread strong to severe thunderstorm development appears
    possible today into tonight across parts of the Upper Midwest
    southward across the lower Missouri Valley into central Great
    Plains. Initially this may be accompanied by a risk for large hail
    and a few strong tornadoes, before damaging wind gusts become the
    most prominent hazard by this evening.

    ...Discussion...
    A couple of notable short wave perturbations have emerged from
    splitting larger-scale mid-level troughing now overspreading the
    northern Rockies and Great Basin. One, including a remnant embedded
    cyclonic circulation, is beginning to accelerate east-northeastward
    into and across the central Canadian/U.S. border vicinity. The
    other is still digging into the eastern Great Basin, but forecast to
    turn across the Wyoming/Colorado Rockies during the day, before
    shearing northeastward toward the Upper Midwest. It appears that
    this will be preceded by several lower amplitude impulses already
    emanating from the subtropical eastern Pacific.

    In lower-levels, a significant cold front is already surging
    southward to the lee of the northern Rockies and forecast to advance
    across much of the remainder of the northern Great Plains by 12Z
    this morning. Models indicate that significant cyclogenesis may
    subsequently ensue northwest/north of Lake Superior toward James Bay
    later today through tonight. At the same time, it appears that a
    secondary frontal wave will migrate northeast of the mid Missouri
    Valley through the Upper Midwest/Great Lakes vicinity. Another lee
    cyclone may attempt to form near/north of the Texas/Oklahoma
    Panhandle vicinity, but probably will be overtaken by the southward
    surging cold front before migrating out of the high plains.

    The northward advection of relatively moist low-level air is ongoing
    from the southern into central Great Plains and lower Missouri
    Valley, and forecast to continue spreading northward within a
    pre-cold frontal plume through portions of the Upper Midwest/Great
    Lakes region by this afternoon. Beneath steep lapse rates, this may
    contribute to sizable mixed-layer CAPE within a corridor from the
    east central Great Plains through the mid/upper Mississippi Valley
    by this afternoon.

    There is notable spread among the various model output concerning
    most of these developments, which may have a significant impact on
    the convective evolution and associated severe weather potential
    today through tonight. However, potential exists for widespread
    convective development capable of producing damaging surface gusts,
    large hail and a couple of strong tornadoes.

    ...Upper Mississippi Valley/Midwest vicinity...
    It appears that a corridor of stronger surface pressure falls may
    shift from western Iowa north-northeastward through western
    Wisconsin by early this afternoon, accompanied by substantive
    boundary-layer destabilization and strengthening southerly low-level
    wind fields with enlarging hodographs. Based on the latest model
    output, including convection allowing guidance, it appears that this
    may contribute to a window of opportunity for discrete supercell
    development within an environment potentially conducive to strong
    tornadoes, before activity grows upscale and eventually outpaces the northeastward boundary-layer destabilization.

    ...Central Great Plains through middle Mississippi Valley/Midwest...

    Uncertainty lingers concerning how quickly the surface cold front
    will tend to undercut a developing corridor of stronger pre-frontal
    surface heating and destabilization, particularly across the central
    into southern Great Plains. However, by early this afternoon, this
    corridor appears likely to develop along an axis from south central
    Kansas toward northwestern Missouri, providing a focus for rapidly
    developing storms including supercells. Initially this may include
    hail exceeding 2 inches in diameter, and potential for a few
    tornadoes before convection grows upscale, spreads east of the axis
    of maximum instability and also become undercut by the front.

    Perhaps aided by forcing associated with one of the perturbations
    emerging from lower latitudes, there appears a signal in model
    output that the upscale growing convection may eventually become
    better organized with one or two notable mesoscale convective
    vortices evolving while spreading ahead of the front across and
    northeast of the lower Missouri Valley late this afternoon and
    evening. Downward mixing of strengthening rear-inflow, within a
    sheared ambient southwesterly deep-layer mean flow already on the
    order of 35-40 kt, widespread strong to severe wind gusts appear
    possible, with strongest gusts and/or perhaps brief tornadoes
    accompanying evolving mesovortices along the gust front.

    The cold front/dryline intersection may become another focus for
    discrete supercell development across parts of south central Kansas
    into adjacent northwestern Oklahoma by late afternoon. However, the
    extent of the associated severe weather potential will depend on how
    quickly this activity is overtaken by the cold front.

    ..Kerr/Lyons.. 04/17/2026

    $$

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  • From COD Weather Processor@1:2320/107 to wx-storm@lists.illinois.edu on Friday, April 17, 2026 12:40:47
    ACUS01 KWNS 171240
    SWODY1
    SPC AC 171239

    Day 1 Convective Outlook
    NWS Storm Prediction Center Norman OK
    0739 AM CDT Fri Apr 17 2026

    Valid 171300Z - 181200Z

    ...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS FROM PARTS OF
    THE UPPER AND MID MISSISSIPPI VALLEY SOUTHWESTWARD INTO KANSAS AND
    OKLAHOMA...

    ...SUMMARY...
    Numerous severe thunderstorms are likely this afternoon into tonight
    across parts of the Upper Midwest southward across the lower
    Missouri Valley into central Great Plains. Initially this may be
    accompanied by a risk for large to giant hail and a few strong
    tornadoes, before severe wind gusts 60 to 90 mph become the
    most prominent hazard by this evening.

    ...Synopsis...
    Surface analysis this morning depicts a front bisecting MN north to
    south to a low near the NE-IA-SD border, with the front extending
    southwestward into the central High Plains. Water-vapor imagery
    shows a prominent upper trough near the MT-ND border
    south-southwestward into eastern UT. A belt of increasingly strong southwesterly 500-mb flow will overspread a destabilizing warm
    sector today as the upper trough eventually reaches the Upper
    Midwest and central Great Plains late tonight. Concurrently, the aforementioned cyclone will develop northeast to Lake Superior as a
    warm front over IA advances northward into the western Great Lakes.
    Meanwhile, the cold front will sweep southeast reaching the central
    Great Lakes southwestward into the southern Great Plains by early
    Saturday.

    ...Upper and Mid Mississippi Valley...
    A northward expanding warm/moist sector on the nose of a 50+ kt
    southerly LLJ will continue to destabilize as large-scale ascent
    approaches from the west. A large-hail threat may develop this
    morning with developing convection across southern MN (see
    forthcoming MCD #472 for short-term details). Heating and advection
    of 60s deg F surface dewpoints beneath steep mid-level lapse rates
    will support the development of a moderately to very unstable
    airmass from IA-IL northward into the upper MS Valley to the east of
    the front and southeast of the low. Upwards of 1500-3000 J/kg
    MLCAPE is forecast immediately ahead of the front with strengthening
    flow aloft, strongly favoring organized storms, including
    supercells. Recent model guidance continues to show the development
    of discrete supercells later this afternoon ahead of the front over
    parts of central/northern WI near the low, and farther south in the
    vicinity of eastern IA into adjacent portions of WI/northwest IL.
    All hazards will be possible with this potential activity, including
    the possibility for an intense tornado. Large to giant hail will be
    possible with supercells. Other storms likely to evolve quickly
    into a band of severe thunderstorms will develop farther west and
    push east coincident with the front. Damaging wind gusts will tend
    to become more prevalent during the evening with linear storm modes.
    Some tornado risk may continue into the evening as maturing bands of
    storms yield a threat for bowing segments and embedded mesovortices,
    before this activity gradually diminishes late as it moves east into
    IN/Lower MI late.

    ...KS-OK eastward into the lower MO Valley...
    Continued moistening and heating of an airmass to the east of a
    dryline/cold front and associated triple point will lead to a very
    unstable airmass from OK into KS by early to mid afternoon. A
    capping inversion will likely inhibit storm development until mid
    afternoon near the front. Initial storm development will likely be supercellular near the triple point before a more extensive band of
    cellular storms develops along the boundary. Both a supercell and
    QLCS tornado risk is apparent given the appreciably large
    CAPE/shear. A coalescing of cold pools and intensification of a
    squall line with embedded surges and bowing segments may result in
    focused swaths of more intense severe gusts (i.e., locally 75-90
    mph) from south-central and eastern KS into west-central MO.
    Farther south, a more conditional setup south of the triple point
    along the dryline is expected. Large to giant hail could accompany
    any mature/sustained supercell along with a tornado risk.
    Eventually the front will sweep southeastward with a convective line
    yielding a risk for wind/hail.

    ..Smith/Dean.. 04/17/2026

    $$

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  • From COD Weather Processor@1:2320/107 to wx-storm@lists.illinois.edu on Friday, April 17, 2026 16:37:20
    ACUS01 KWNS 171637
    SWODY1
    SPC AC 171635

    Day 1 Convective Outlook
    NWS Storm Prediction Center Norman OK
    1135 AM CDT Fri Apr 17 2026

    Valid 171630Z - 181200Z

    ...THERE IS A MODERATE RISK OF SEVERE THUNDERSTORMS FROM FAR
    NORTHWEST OKLAHOMA THROUGH CENTRAL AND EASTERN KANSAS INTO
    WEST-CENTRAL MISSOURI...

    ...SUMMARY...
    Numerous severe thunderstorms are likely this afternoon into tonight
    across parts of the Upper Midwest southward across the lower
    Missouri Valley and central/southern Great Plains. Initially this
    may be accompanied by a risk for large to giant hail and a few
    strong tornadoes, before severe wind gusts of 60 to 90 mph become
    the most prominent hazard by this evening.

    ...Synopsis...
    Recent surface analysis places a low over south-central MN, with a
    cold front extending southwestward to another low over central KS. A
    warm front also extends southwestward from the MN low through far
    southwest MN and far northern IL into central IN. This warm front is
    demarcated well by the 56 deg F isodrosotherm. Farther south, a
    dryline extends from the triple point KS low back southwestward
    through the TX Panhandle and into far southeast NM. A broad, moist
    warm sector exists to the east of the cold front and dryline,
    characterized largely by dewpoints in the low to mid 60s.

    A well-defined shortwave trough is apparent on satellite imagery,
    extending from southern Saskatchewan back southwestward into the
    eastern Great Basin. This wave is forecast to continue eastward,
    with a attendant increase in the mid-level flow across much of the
    Plains and Upper/Mid MS Valley. The cold front will surge eastward/southeastward in response to this wave as well, interacting
    with the warm sector to support numerous strong to severe
    thunderstorms from parts of the Upper Midwest southward across the
    lower Missouri Valley into southern Plains.

    ...Upper/Mid MS Valley...
    Moderate to strong low-level moisture advection is expected across
    the Upper MS Valley today as the surface low mentioned in the
    synopsis progresses northeastward, with an attendant northward shift
    of the warm front as well. The risk across this region may evolve in
    several phases, beginning with the elevated thunderstorms currently
    ongoing across northwest WI. This storms will likely continue
    northeastward, posing a risk for severe hail and isolated damaging
    gusts. Additional development is possible northwest of this activity
    along the occluded front, with some hail possible here as well.

    Farther south, the northeastward advecting low-level moisture
    coupled with strong heating and steep lapse rates will result in a
    strongly unstable airmass along and just south of the warm front by
    the early afternoon. Storm initiation is anticipated within this
    open warm sector by early afternoon, forced by a mix of warm-air
    advection, low-level confluence, and subtly increasing large-scale
    ascent. This activity should be ahead of the front and initially
    discrete. The overall parameter space will be characterized by
    strong to very strong buoyancy, moderate deep-layer vertical shear,
    and strong low-level helicity. Supercells capable of all hazards are
    expected, including large to very large (i.e. 3"+ hail), strong to
    intense tornadoes, and severe wind gusts. Storm interactions are
    expected to strongly influence the tornado risk, with the initially
    discrete mode likely becoming messy quickly.

    Farther west, other storms are likely to evolve quickly along the
    front, developing into a band of severe thunderstorms that will push
    east coincident with the front. Damaging wind gusts will tend to
    become more prevalent during the evening with linear storm modes.
    Some tornado risk may continue into the evening as maturing bands of
    storms yield a threat for bowing segments and embedded mesovortices,
    before this activity gradually diminishes late as it moves east into
    IN/Lower MI late.

    ...KS/OK/MO...
    A very unstable airmass is expected to develop along and ahead of
    the triple point over south-central KS an associated cold front and
    dryline. Strong low-level convergence will likely lead to initial
    storm development near the triple point. This initial activity will
    be supercellular and capable of very large to giant hail (over
    3-3.5" in diameter). Highest coverage of very large hail is expected
    over from far northwest OK into south-central KS. Strong downdrafts
    (60 to 80 mph) are possible as well. With a largely
    boundary-parallel orientation to the deep-layer shear, the tornado
    risk appears relatively lower. However, given the supercell mode and
    potential interactions with outflow, a low-probability tornado risk
    remains. A more north-south configuration to the dryline supports a
    conditional tornado risk into far northwest TX.

    With time, upscale growth and the development of a
    forward-propagating MCS is anticipated across central and eastern
    KS. Very strong gusts (80+ mph) are possible with this MCS.
    Additionally, some QLCS tornado risk will exist within this line as
    long as it stays ahead of the surging cold front. The front will
    continue sweeping southeastward, with storms along this boundary
    yielding a risk for wind/hail.

    ..Mosier/Chalmers.. 04/17/2026

    $$

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  • From COD Weather Processor@1:2320/107 to wx-storm@lists.illinois.edu on Friday, April 17, 2026 19:55:21
    ACUS01 KWNS 171955
    SWODY1
    SPC AC 171953

    Day 1 Convective Outlook
    NWS Storm Prediction Center Norman OK
    0253 PM CDT Fri Apr 17 2026

    Valid 172000Z - 181200Z

    ...THERE IS A MODERATE RISK OF SEVERE THUNDERSTORMS FROM FAR
    NORTHWEST OKLAHOMA THROUGH CENTRAL AND EASTERN KANSAS INTO
    WEST-CENTRAL MISSOURI...

    ...SUMMARY...
    Numerous severe thunderstorms are likely this afternoon into tonight
    across parts of the Upper Midwest southward across the lower
    Missouri Valley and central/southern Great Plains. Initially this
    may be accompanied by a risk for large to giant hail and a few
    strong tornadoes, before severe wind gusts of 60 to 90 mph become
    the most prominent hazard by this evening.

    ...20Z Update...
    Severe probabilities have been adjusted to account for progression
    of the cold front this afternoon. The remainder of the forecast is
    unchanged. See MD 475 for short-term details of evolving tornado
    risk along the Illinois/Wisconsin border.

    ..Wendt.. 04/17/2026

    .PREV DISCUSSION... /ISSUED 1203 PM CDT Fri Apr 17 2026/

    ...Synopsis...
    Recent surface analysis places a low over south-central MN, with a
    cold front extending southwestward to another low over central KS. A
    warm front also extends southwestward from the MN low through far
    southwest MN and far northern IL into central IN. This warm front is
    demarcated well by the 56 deg F isodrosotherm. Farther south, a
    dryline extends from the triple point KS low back southwestward
    through the TX Panhandle and into far southeast NM. A broad, moist
    warm sector exists to the east of the cold front and dryline,
    characterized largely by dewpoints in the low to mid 60s.

    A well-defined shortwave trough is apparent on satellite imagery,
    extending from southern Saskatchewan back southwestward into the
    eastern Great Basin. This wave is forecast to continue eastward,
    with a attendant increase in the mid-level flow across much of the
    Plains and Upper/Mid MS Valley. The cold front will surge eastward/southeastward in response to this wave as well, interacting
    with the warm sector to support numerous strong to severe
    thunderstorms from parts of the Upper Midwest southward across the
    lower Missouri Valley into southern Plains.

    ...Upper/Mid MS Valley...
    Moderate to strong low-level moisture advection is expected across
    the Upper MS Valley today as the surface low mentioned in the
    synopsis progresses northeastward, with an attendant northward shift
    of the warm front as well. The risk across this region may evolve in
    several phases, beginning with the elevated thunderstorms currently
    ongoing across northwest WI. This storms will likely continue
    northeastward, posing a risk for severe hail and isolated damaging
    gusts. Additional development is possible northwest of this activity
    along the occluded front, with some hail possible here as well.

    Farther south, the northeastward advecting low-level moisture
    coupled with strong heating and steep lapse rates will result in a
    strongly unstable airmass along and just south of the warm front by
    the early afternoon. Storm initiation is anticipated within this
    open warm sector by early afternoon, forced by a mix of warm-air
    advection, low-level confluence, and subtly increasing large-scale
    ascent. This activity should be ahead of the front and initially
    discrete. The overall parameter space will be characterized by
    strong to very strong buoyancy, moderate deep-layer vertical shear,
    and strong low-level helicity. Supercells capable of all hazards are
    expected, including large to very large (i.e. 3"+ hail), strong to
    intense tornadoes, and severe wind gusts. Storm interactions are
    expected to strongly influence the tornado risk, with the initially
    discrete mode likely becoming messy quickly.

    Farther west, other storms are likely to evolve quickly along the
    front, developing into a band of severe thunderstorms that will push
    east coincident with the front. Damaging wind gusts will tend to
    become more prevalent during the evening with linear storm modes.
    Some tornado risk may continue into the evening as maturing bands of
    storms yield a threat for bowing segments and embedded mesovortices,
    before this activity gradually diminishes late as it moves east into
    IN/Lower MI late.

    ...KS/OK/MO...
    A very unstable airmass is expected to develop along and ahead of
    the triple point over south-central KS an associated cold front and
    dryline. Strong low-level convergence will likely lead to initial
    storm development near the triple point. This initial activity will
    be supercellular and capable of very large to giant hail (over
    3-3.5" in diameter). Highest coverage of very large hail is expected
    over from far northwest OK into south-central KS. Strong downdrafts
    (60 to 80 mph) are possible as well. With a largely
    boundary-parallel orientation to the deep-layer shear, the tornado
    risk appears relatively lower. However, given the supercell mode and
    potential interactions with outflow, a low-probability tornado risk
    remains. A more north-south configuration to the dryline supports a
    conditional tornado risk into far northwest TX.

    With time, upscale growth and the development of a
    forward-propagating MCS is anticipated across central and eastern
    KS. Very strong gusts (80+ mph) are possible with this MCS.
    Additionally, some QLCS tornado risk will exist within this line as
    long as it stays ahead of the surging cold front. The front will
    continue sweeping southeastward, with storms along this boundary
    yielding a risk for wind/hail.

    $$

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  • From COD Weather Processor@1:2320/107 to wx-storm@lists.illinois.edu on Saturday, April 18, 2026 01:01:25
    ACUS01 KWNS 180101
    SWODY1
    SPC AC 180059

    Day 1 Convective Outlook
    NWS Storm Prediction Center Norman OK
    0759 PM CDT Fri Apr 17 2026

    Valid 180100Z - 181200Z

    ...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS OVER MUCH OF
    ILLINOIS INTO NORTHEAST MISSOURI...AND OVER NORTHERN OKLAHOMA...

    ...SUMMARY...
    Damaging storms producing wind, hail and isolated tornadoes remain
    possible this evening from Illinois into Oklahoma.

    ...WI/MI into IL and MO...
    Supercells have largely merged into a broken line of assorted bows
    from far southeast WI across much of northern into western IL and
    trailing into northeast MO. The 00Z ILX sounding shows steep lapse
    rates aloft and large deep-layer shear, as well as veering winds
    with height. Low-level SRH will remain favorable for rotation to
    develop at least briefly anywhere within the line, with damaging
    winds the most likely threat. Storms have recently become better
    organized over central MO, and this activity may affect the St.
    Louis area later tonight. For lower MI into northern IN, the
    organized line of storms to the west along with a 60 kt low-level
    jet suggest at least isolated severe gusts may occur overnight
    despite lesser instability.

    For more information about Illinois, see mesoscale discussion 484.

    ...OK...Southeast KS...southwest MO...northwest AR...
    Scattered severe cells persist near and north of the cold front
    across much of northern OK and extending into southeast KS. Although
    the undercutting cold air will likely mitigate wind potential, steep
    lapse rates aloft along with ample deep-layer shear will continue to
    favor hail. Storm coverage may be more isolated into southwest OK
    later tonight, but the environment remains quite favorable for large
    hail.

    One corridor for possible damaging wind or even a tornado is over
    northeast OK into southwest MO. Here, the front is not surging as
    fast, and storms over Osage county are already oriented more
    favorably N-S relative to the deep-layer shear. A southwest
    low-level jet near 50 kt will further support low-level rotation.

    ..Jewell.. 04/18/2026

    $$

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  • From COD Weather Processor@1:2320/107 to wx-storm@lists.illinois.edu on Saturday, April 18, 2026 04:54:56
    ACUS01 KWNS 180454
    SWODY1
    SPC AC 180453

    Day 1 Convective Outlook
    NWS Storm Prediction Center Norman OK
    1153 PM CDT Fri Apr 17 2026

    Valid 181200Z - 191200Z

    ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS OVER PARTS OF THE
    UPPER OHIO VALLEY TO THE APPALACHIANS...

    ...SUMMARY...
    Scattered strong to severe thunderstorms capable of damaging winds
    and hail will be possible on Saturday across the upper Ohio Valley
    and central Appalachians. Isolated severe hail is also possible
    across parts of central Texas.

    ...Synopsis...
    A large upper trough with elongated leading speed max will sweep
    across the Great Lakes and OH Valley during the day and into the
    Appalachians by Sunday morning. Meanwhile, moderate westerlies aloft
    will persist across TX with the aid of a subtropical jet.

    At the surface, a cold front will move across OH and KY through
    early afternoon, and into western NY, PA, and WV late in the day.
    This front will also extend far southwestward toward the
    northwestern Gulf Coast and into far southern TX. Ahead of the
    front, a narrow plume of 50s to lower 60s F dewpoints will exist as
    far north as OH and PA, with more robust moisture into TX with upper
    60s F dewpoints.

    ...Upper Ohio Valley/Appalachians...
    A remnant line of showers and thunderstorms is expected to persist
    near the cold front this morning as it moves across the OH Valley
    and toward the lower Great Lakes. Daytime heating will help
    destabilize the air mass ahead of this activity, and storm
    rejuvenation is expected after 18Z from near Lake Erie into eastern
    KY. These storms will mature in the 21-00Z timeframe, affecting
    eastern OH, WV, and into PA and possibly southwest NY.

    Substantial southwest flow aloft will help to push these storms
    quickly east/northeast across the region, and deep-layer shear may
    favor scattered cells initially. Marginal hail will be possible,
    along with locally strong gusts, especially as storm mode becomes
    linear and peak heating has been achieved. Given the narrow
    instability axis, storms should wane after sunset.

    ...South-Central Texas...
    Scattered showers and elevated thunderstorms are expected throughout
    much of the day as the cold front rapidly undercuts a moist and
    unstable air mass. Forecast soundings show MUCAPE parcels rooted in
    the 850-700 mb layer, with effective deep-layer shear of 50-60 kt.
    Initial activity may develop over central TX during the morning and
    through midday, with additional new elevated development translating
    southward as the front continually lifts the moist air mass. A few
    hail reports at or above 1.00" will be possible.

    ..Jewell/Moore.. 04/18/2026

    $$

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  • From COD Weather Processor@1:2320/107 to wx-storm@lists.illinois.edu on Saturday, April 18, 2026 12:33:55
    ACUS01 KWNS 181233
    SWODY1
    SPC AC 181232

    Day 1 Convective Outlook
    NWS Storm Prediction Center Norman OK
    0732 AM CDT Sat Apr 18 2026

    Valid 181300Z - 191200Z

    ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS OVER PARTS OF THE
    UPPER OHIO VALLEY TO THE APPALACHIANS...

    ...SUMMARY...
    Scattered strong to severe thunderstorms capable mainly of damaging
    winds will be possible today across the upper Ohio Valley and
    central Appalachians.

    ...Synopsis...
    Water-vapor imagery this morning shows a large-scale upper trough
    over the Upper Midwest into the south-central Plains. An elongated
    mid-level vorticity lobe and associated speed max will quickly move
    eastward across the Midwest today and reach the Lower Great Lakes
    and upper OH Valley late tonight. Farther south, a belt of strong west-southwesterly flow associated with a subtropical jet will
    reside over TX.

    A cold front extending from a low near James Bay southward through
    the Great Lakes and into TX will continue to push east and southeast
    through the period. Convective outflow over the OH Valley to the
    east of the front will eventually be overtaken by the front later
    today as a band of showers/thunderstorms develops over the upper OH
    Valley by early afternoon.

    ...OH Valley into the Appalachians...
    Some heating combined with a gradually moistening airmass (55-60 deg
    F surface dewpoints) will result in weak destabilization by midday
    as convective development ensues near the preceding outflow/wind
    shift and front. Ample mid to high-level flow will aid in some
    potential for storm organization, mainly in the form of a few
    stronger cells and linear bands. Widely scattered strong to severe
    gusts capable of wind damage will likely be the primary hazard, but
    an isolated risk for hail or a brief tornado is possible with the
    strongest cells. This activity will likely weaken by early evening
    as it encounters a slightly drier and less unstable airmass with
    east extent.

    ...Central Texas...
    Scattered showers and elevated thunderstorms are expected throughout
    much of the day as the cold front rapidly undercuts a moist and
    unstable air mass. The 12 UTC Del Rio, TX raob shows an 8.2 deg
    C/km 700-500 mb lapse rate. Forecast soundings show MUCAPE parcels
    rooted in the 850-700 mb layer, with effective deep-layer shear of
    50-60 kt. Although an isolated risk for large hail appears to be
    the main hazard with the stronger cells, there has been some
    indication that a localized risk for severe gusts could accompany
    the strongest cores. For short-term details regarding a risk for
    hail/wind with a few stronger thunderstorms this morning extending
    from the Concho Valley east-northeast towards DFW, reference MCD
    #490.

    ..Smith/Dean.. 04/18/2026

    $$

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  • From COD Weather Processor@1:2320/107 to wx-storm@lists.illinois.edu on Saturday, April 18, 2026 16:05:29
    ACUS01 KWNS 181605
    SWODY1
    SPC AC 181603

    Day 1 Convective Outlook
    NWS Storm Prediction Center Norman OK
    1103 AM CDT Sat Apr 18 2026

    Valid 181630Z - 191200Z

    ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS THIS AFTERNOON
    ACROSS PARTS OF THE UPPER OHIO VALLEY AND LOWER GREAT LAKES
    REGION....

    ...SUMMARY...
    Widely scattered strong to severe thunderstorms capable mainly of
    damaging winds will be possible today across the Upper Ohio Valley
    and Lower Great Lakes.

    ...Upper OH Valley...
    Latest surface analysis shows a cold front pushing eastward across
    western OH, associated with a band of widespread clouds and light precipitation. Mostly clear skies are present ahead of the front,
    where temperatures are warming through the 70s. This will lead to a
    corridor of marginal afternoon instability and the potential for
    scattered thunderstorm intensification along the front. Forecast
    soundings show strong mid-level winds and steep low-level lapse
    rates, supportive of strong downdrafts in any vigorous convection.
    However, CAM guidance is consistent in showing very few
    organized/strong storms through the day. Will maintain the SLGT
    risk for the conditional risk of a few damaging wind events, but
    with limited confidence.

    ...TX...
    Isolated intense thunderstorms have been ongoing this morning in the post-frontal regime across central TX. These storms have produced
    hail and gusty winds for several hours. It appears likely that this
    scenario will shift eastward and weaken early this afternoon as the
    primary upper jet moves into AR and away from the region, but will
    maintain the MRGL risk area for a few more hours and extend it into
    parts of AR/LA.

    ..Hart/Chalmers.. 04/18/2026

    $$

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  • From COD Weather Processor@1:2320/107 to wx-storm@lists.illinois.edu on Saturday, April 18, 2026 20:06:59
    ACUS01 KWNS 182006
    SWODY1
    SPC AC 182005

    Day 1 Convective Outlook
    NWS Storm Prediction Center Norman OK
    0305 PM CDT Sat Apr 18 2026

    Valid 182000Z - 191200Z

    ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS WITHIN THE
    CENTRAL APPALACHIANS INTO THE UPPER OHIO VALLEY VICINITY...AND PARTS
    OF CENTRAL TEXAS...

    ...SUMMARY...
    Isolated marginally severe hail is possible in portions of central
    Texas. Isolated damaging winds remain possible from the central
    Appalachians into the Upper Ohio Valley vicinity.

    ...20Z Update...
    Based on observational trends 15% wind probabilities were removed
    from the Upper Ohio Valley vicinity. Wind gusts along with weak,
    shallow convection (with little lightning) have generally been in
    the 30 kt range with isolated cases of low 40 kt gusts. Isolated
    wind damage remains possible, but a more organized threat is not
    expected given weak buoyancy downstream. Elsewhere, marginally
    severe hail remains possible with isolated, elevated convection in
    central Texas.

    ..Wendt.. 04/18/2026

    .PREV DISCUSSION... /ISSUED 1103 AM CDT Sat Apr 18 2026/

    ...Upper OH Valley...
    Latest surface analysis shows a cold front pushing eastward across
    western OH, associated with a band of widespread clouds and light precipitation. Mostly clear skies are present ahead of the front,
    where temperatures are warming through the 70s. This will lead to a
    corridor of marginal afternoon instability and the potential for
    scattered thunderstorm intensification along the front. Forecast
    soundings show strong mid-level winds and steep low-level lapse
    rates, supportive of strong downdrafts in any vigorous convection.
    However, CAM guidance is consistent in showing very few
    organized/strong storms through the day. Will maintain the SLGT
    risk for the conditional risk of a few damaging wind events, but
    with limited confidence.

    ...TX...
    Isolated intense thunderstorms have been ongoing this morning in the post-frontal regime across central TX. These storms have produced
    hail and gusty winds for several hours. It appears likely that this
    scenario will shift eastward and weaken early this afternoon as the
    primary upper jet moves into AR and away from the region, but will
    maintain the MRGL risk area for a few more hours and extend it into
    parts of AR/LA.

    $$

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  • From COD Weather Processor@1:2320/107 to wx-storm@lists.illinois.edu on Sunday, April 19, 2026 00:24:00
    ACUS01 KWNS 190023
    SWODY1
    SPC AC 190022

    Day 1 Convective Outlook
    NWS Storm Prediction Center Norman OK
    0722 PM CDT Sat Apr 18 2026

    Valid 190100Z - 191200Z

    ...NO SEVERE THUNDERSTORM AREAS FORECAST...

    ...SUMMARY...
    Severe storms are unlikely through tonight.

    ...Synopsis...
    Little thunderstorm activity is currently present near the cold
    front moving across NY and PA, with only isolated lightning flashes
    across WV into western VA. Given the loss of heating, and already
    minimal instability present, severe storms appear unlikely to
    develop.

    Farther south, scattered storms exist over northern AL near the
    front, and north of the boundary from LA into central TX. In both
    these areas, instability is weak, and generally should not support a
    severe threat as the surface air mass cools.

    ..Jewell.. 04/19/2026

    $$

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  • From COD Weather Processor@1:2320/107 to wx-storm@lists.illinois.edu on Sunday, April 19, 2026 05:19:34
    ACUS01 KWNS 190519
    SWODY1
    SPC AC 190517

    Day 1 Convective Outlook
    NWS Storm Prediction Center Norman OK
    1217 AM CDT Sun Apr 19 2026

    Valid 191200Z - 201200Z

    ...NO SEVERE THUNDERSTORM AREAS FORECAST...

    ...SUMMARY...
    Severe thunderstorms are not forecast today.

    ...Synopsis...
    A large upper trough extending from the Great Lakes into the OH and
    TN Valleys will move into the northeastern US today, with a weak
    upper ridge across the Rockies. This pattern will favor high
    pressure over the central and eastern states, stable conditions and
    minimal thunderstorm activity. A cold front associated the eastern
    trough will be well off the East Coast by midday, with drying
    offshore flow. Minimal instability may yield isolated thunderstorms
    over eastern Florida, or perhaps across the Rio Grande Valley where
    elevated moisture and weak instability will remain atop the surface
    cool layer. In any case, severe storms are not forecast.

    ..Jewell/Moore.. 04/19/2026

    $$

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  • From COD Weather Processor@1:2320/107 to wx-storm@lists.illinois.edu on Sunday, April 19, 2026 12:45:04
    ACUS01 KWNS 191244
    SWODY1
    SPC AC 191243

    Day 1 Convective Outlook
    NWS Storm Prediction Center Norman OK
    0743 AM CDT Sun Apr 19 2026

    Valid 191300Z - 201200Z

    ...NO SEVERE THUNDERSTORM AREAS FORECAST...

    ...SUMMARY...
    Severe thunderstorms are not forecast today.

    ...Synopsis...
    Water-vapor imagery this morning shows a large-scale upper trough
    from James Bay southward through the Great Lakes and TN Valley. The
    upper trough will continue to move east and reach the Lower Great
    Lakes and East Coast by daybreak Monday. In the low levels, a cold
    front will push east of the Carolina coast by early afternoon.
    Surface high pressure will influence conditions across the central
    and eastern states in wake of the cold front. Weak instability will
    yield isolated thunderstorms over parts of the south Florida,
    eastern North Carolina, and weak elevated storms over south Texas.

    ..Smith/Thompson.. 04/19/2026

    $$

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  • From COD Weather Processor@1:2320/107 to wx-storm@lists.illinois.edu on Sunday, April 19, 2026 16:01:33
    ACUS01 KWNS 191601
    SWODY1
    SPC AC 191559

    Day 1 Convective Outlook
    NWS Storm Prediction Center Norman OK
    1059 AM CDT Sun Apr 19 2026

    Valid 191630Z - 201200Z

    ...NO SEVERE THUNDERSTORM AREAS FORECAST...

    ...SUMMARY...
    Severe thunderstorms are not forecast today.

    ...Synopsis...
    A shortwave trough currently approaching Baja California will
    provide increasing large-scale forcing for ascent over Mexico and
    south/west TX today. This will lead to scattered thunderstorms
    through the period.

    Other isolated afternoon thunderstorms are expected ahead of a
    frontal band affecting New England and eastern NC, beneath cold air
    aloft in the Lower Great Lakes region, and over south FL. In all of
    these areas, weak instability and/or limited vertical shear will
    preclude a risk of organized severe storms.

    ..Hart/Bunting.. 04/19/2026

    $$

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  • From COD Weather Processor@1:2320/107 to wx-storm@lists.illinois.edu on Sunday, April 19, 2026 19:57:06
    ACUS01 KWNS 191957
    SWODY1
    SPC AC 191955

    Day 1 Convective Outlook
    NWS Storm Prediction Center Norman OK
    0255 PM CDT Sun Apr 19 2026

    Valid 192000Z - 201200Z

    ...NO SEVERE THUNDERSTORM AREAS FORECAST...

    ...SUMMARY...
    Severe thunderstorms are not forecast today.

    ...20Z Update...
    The TSTM area was removed in eastern NC, where the cold front and
    related thunderstorm potential has shifted offshore. The TSTM area
    was also trimmed behind a band of eastward-moving thunderstorms
    departing the New England coast, and no lightning is expected behind
    this activity. Farther south in parts of central FL, isolated
    thunderstorms are evolving along the sea breeze focused over the
    Treasure Coast. While storm coverage and intensity are expected to
    remain isolated/marginal, a warm/unstable PBL and around 35 kt of
    midlevel flow could support a strong storm or two capable of locally
    strong gusts, though this activity is expected to remain sub-severe.

    ..Weinman.. 04/19/2026

    .PREV DISCUSSION... /ISSUED 1059 AM CDT Sun Apr 19 2026/

    ...Synopsis...
    A shortwave trough currently approaching Baja California will
    provide increasing large-scale forcing for ascent over Mexico and
    south/west TX today. This will lead to scattered thunderstorms
    through the period.

    Other isolated afternoon thunderstorms are expected ahead of a
    frontal band affecting New England and eastern NC, beneath cold air
    aloft in the Lower Great Lakes region, and over south FL. In all of
    these areas, weak instability and/or limited vertical shear will
    preclude a risk of organized severe storms.

    $$

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  • From COD Weather Processor@1:2320/107 to wx-storm@lists.illinois.edu on Monday, April 20, 2026 00:06:09
    ACUS01 KWNS 200006
    SWODY1
    SPC AC 200004

    Day 1 Convective Outlook
    NWS Storm Prediction Center Norman OK
    0704 PM CDT Sun Apr 19 2026

    Valid 200100Z - 201200Z

    ...NO SEVERE THUNDERSTORM AREAS FORECAST...

    ...SUMMARY...
    Severe thunderstorms are not forecast.

    ...Synopsis...
    Scattered thunderstorms currently exist along a cold front mainly
    over the western Atlantic Ocean, and earlier affected Downeast
    Maine. Thunderstorms chances have ended there as the front has now
    pushed through the area.

    To the west, broken arc of elevated thunderstorms extends from near
    El Paso southeastward across the Rio Grande Valley. This area is in
    a zone of theta-e advection just off the surface, with unstable
    parcels rooted in the 850-700 mb layer. Weak instability will
    preclude much of a hail risk, but overall storm chances should
    continue to increase into central TX tonight.

    ..Jewell.. 04/20/2026

    $$

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  • From COD Weather Processor@1:2320/107 to wx-storm@lists.illinois.edu on Monday, April 20, 2026 04:20:18
    ACUS01 KWNS 200420
    SWODY1
    SPC AC 200418

    Day 1 Convective Outlook
    NWS Storm Prediction Center Norman OK
    1118 PM CDT Sun Apr 19 2026

    Valid 201200Z - 211200Z

    ...NO SEVERE THUNDERSTORM AREAS FORECAST...

    ...SUMMARY...
    Severe storms are not expected today.

    ...Synopsis...
    An upper trough will exit the northeastern states today, with
    northwest flow aloft extending from the northern Plains to the East
    Coast. Upper ridging will occur over the Rockies, while a large
    upper trough slowly approaches the West Coast.

    At the surface, high pressure will result in relatively stable
    conditions for much of the central and eastern CONUS, with centers
    over the Mid Atlantic and near the northern Gulf Coast.

    In the wake of the eastern trough, winds just off the surface will
    maintain a zone of elevated moisture and instability over much of
    TX, where scattered showers and storms will be most likely. Weak
    instability will preclude any severe storm chances there.

    To the west, cooling aloft with the approaching upper trough will
    support weak instability into parts of OR and WA, with isolated late
    day thunderstorms possible over portions of the Cascades.
    Small/non-severe hail cannot be ruled out, along with locally gusty
    winds mainly in the 00-03Z time frame.

    ..Jewell/Chalmers.. 04/20/2026

    $$

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  • From COD Weather Processor@1:2320/107 to wx-storm@lists.illinois.edu on Monday, April 20, 2026 12:20:17
    ACUS01 KWNS 201220
    SWODY1
    SPC AC 201218

    Day 1 Convective Outlook
    NWS Storm Prediction Center Norman OK
    0718 AM CDT Mon Apr 20 2026

    Valid 201300Z - 211200Z

    ...NO SEVERE THUNDERSTORM AREAS FORECAST...

    ...SUMMARY...
    Severe storms are not expected today.

    ...Synopsis...
    Water-vapor imagery this morning shows a weak upper trough centered
    over AZ and Sonora moving east undercutting a ridge over the
    Rockies. This upper feature will move into the southern High Plains
    by late tonight. Farther west, a mid- to upper-level low will move
    slowly east from the eastern Pacific toward the CA/OR coast.

    Scattered showers and weak elevated storms will be possible across a
    large portion of TX today. Farther west, isolated to scattered
    thunderstorms are possible in association with the weak upper trough
    over parts of the Desert Southwest. Primarily diurnal storm
    activity over the southern FL Peninsula is expected, as well as
    isolated late day thunderstorms over portions of the Cascades.

    Elsewhere, surface high pressure will lead to tranquil conditions
    across much of the CONUS precluding storm development.

    ..Smith/Thompson.. 04/20/2026

    $$

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  • From COD Weather Processor@1:2320/107 to wx-storm@lists.illinois.edu on Monday, April 20, 2026 15:54:10
    ACUS01 KWNS 201554
    SWODY1
    SPC AC 201552

    Day 1 Convective Outlook
    NWS Storm Prediction Center Norman OK
    1052 AM CDT Mon Apr 20 2026

    Valid 201630Z - 211200Z

    ...NO SEVERE THUNDERSTORM AREAS FORECAST...

    ...SUMMARY...
    Severe storms are not expected today.

    ...Synopsis...
    An upper impulse will continue to pose a risk of scattered
    thunderstorms over parts of NM and south/west TX through the
    afternoon, with activity spreading into north-central TX late
    tonight.

    Other thunderstorms are possible this afternoon and evening over
    south FL in a moist and marginally unstable air mass, along the
    coast of southern New England, and over portions of OR/WA. In all
    areas, weak instability will preclude the risk of organized severe
    storms.

    ..Hart/Flournoy.. 04/20/2026

    $$

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  • From COD Weather Processor@1:2320/107 to wx-storm@lists.illinois.edu on Monday, April 20, 2026 19:47:40
    ACUS01 KWNS 201947
    SWODY1
    SPC AC 201946

    Day 1 Convective Outlook
    NWS Storm Prediction Center Norman OK
    0246 PM CDT Mon Apr 20 2026

    Valid 202000Z - 211200Z

    ...NO SEVERE THUNDERSTORM AREAS FORECAST...

    ...SUMMARY...
    Severe storms are not expected today.

    ...20Z Update...
    The TSTM area over the coast of southern New England and the
    Mid-Atlantic was removed, as large-scale forcing for ascent and
    related thunderstorm activity has shifted offshore. Elsewhere, the
    previous forecast remains on track.

    ..Weinman.. 04/20/2026

    .PREV DISCUSSION... /ISSUED 1052 AM CDT Mon Apr 20 2026/

    ...Synopsis...
    An upper impulse will continue to pose a risk of scattered
    thunderstorms over parts of NM and south/west TX through the
    afternoon, with activity spreading into north-central TX late
    tonight.

    Other thunderstorms are possible this afternoon and evening over
    south FL in a moist and marginally unstable air mass, along the
    coast of southern New England, and over portions of OR/WA. In all
    areas, weak instability will preclude the risk of organized severe
    storms.

    $$

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  • From COD Weather Processor@1:2320/107 to wx-storm@lists.illinois.edu on Tuesday, April 21, 2026 00:58:43
    ACUS01 KWNS 210058
    SWODY1
    SPC AC 210057

    Day 1 Convective Outlook
    NWS Storm Prediction Center Norman OK
    0757 PM CDT Mon Apr 20 2026

    Valid 210100Z - 211200Z

    ...NO SEVERE THUNDERSTORM AREAS FORECAST...

    ...SUMMARY...
    Severe storms are not expected through tonight.

    ...Discussion...
    Scattered thunderstorms persist across central and southern TX this
    evening, where southerly 850 mb winds are aiding lift/warm advection
    atop the relatively cool boundary layer. In addition, a weak wave
    aloft is moving across the southern Plains. As such, storms may
    increase in coverage through tonight, expanding into northern and
    eastern TX. Effective shear will remain weak especially over
    northern areas, and severe storms are not expected.

    Elsewhere, showers will generally decrease over far southern FL with
    the loss of heating. Farther west, an isolated lightning flash
    cannot be ruled out over parts of the WA/OR Cascades as an offshore
    upper trough slowly pushes east.

    ..Jewell.. 04/21/2026

    $$

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  • From COD Weather Processor@1:2320/107 to wx-storm@lists.illinois.edu on Tuesday, April 21, 2026 05:38:44
    ACUS01 KWNS 210538
    SWODY1
    SPC AC 210537

    Day 1 Convective Outlook
    NWS Storm Prediction Center Norman OK
    1237 AM CDT Tue Apr 21 2026

    Valid 211200Z - 221200Z

    ...NO SEVERE THUNDERSTORM AREAS FORECAST...

    ...SUMMARY...
    Thunderstorms are expected today over much of Texas, from Illinois
    into Ohio, and over portions of central California. Severe weather
    is not currently forecast.

    ...Synopsis...
    An upper ridge will move into the Plains as an upper trough moves
    inland over the West, with a strong cyclonic speed max moving across
    CA and into the Great Basin. Meanwhile, northwest flow aloft will
    extend from the Great Lakes into the Mid Atlantic. Farther south, a
    weakening disturbance will move out of TX and toward the lower MS
    Valley.

    At the surface, high pressure will remain over much of the eastern
    states and across the Gulf Coast. Southerly winds across the Plains
    and around this high may support mid to upper 50s F dewpoints as far
    north as IA and IL by 00Z, while higher dewpoints remain relegated
    to southern TX. Here, scattered showers and thunderstorms will
    likely be ongoing early on Tuesday where weak elevated instability
    will remain.

    ...IL/IN/OH...
    A surface trough is forecast to develop from Lower MI into southern
    WI and northern IL by late afternoon, beneath the northwest flow
    regime and with cool midlevel temperatures. Southwest surface winds
    and daytime heating should lead to 40s and 50s F dewpoints, with a
    relatively dry boundary layer overall. Models suggest at least
    isolated late day and evening thunderstorms will develop ahead of
    this trough, though instability levels are uncertain. Despite
    marginal dewpoints/moisture, the cool temperatures aloft may support
    a few cells capable of small hail from IL into IN by late afternoon.
    Wind gust potential is more uncertain and dependent on storm
    coverage/outflow production, with the dry boundary layer
    conditionally helping strong gust potential into the evening and
    perhaps overnight.

    ...Central CA...
    Cold temperatures aloft north of the midlevel jet will support weak
    instability over parts of the central Valleys. Given early
    precipitation and clouds, as well as marginal low-level shear,
    severe storms appear unlikely. However, a few strong storms may
    occur late in the afternoon if sufficient heating occurs behind the
    early day rain. Small hail appears most probable with the strongest
    cells.

    ..Jewell.. 04/21/2026

    $$

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  • From COD Weather Processor@1:2320/107 to wx-storm@lists.illinois.edu on Tuesday, April 21, 2026 12:40:47
    ACUS01 KWNS 211240
    SWODY1
    SPC AC 211239

    Day 1 Convective Outlook
    NWS Storm Prediction Center Norman OK
    0739 AM CDT Tue Apr 21 2026

    Valid 211300Z - 221200Z

    ...NO SEVERE THUNDERSTORM AREAS FORECAST...

    ...SUMMARY...
    Organized severe thunderstorms are not currently forecast across the
    contiguous United States through tonight.

    ...IL/IN...
    Morning water-vapor imagery shows a subtle disturbance over the mid
    MO Valley, which is forecast to quickly move southeast into the
    southern Great Lakes by early evening. An associated surface trough
    is forecast to develop from Lower MI into southern WI and northern
    IL by late afternoon. Despite modest moisture (upper 40s to mid 50s
    deg F surface dewpoints) returning northward into the Cornbelt, cold
    mid-level temperatures (around -16 to -18 deg C at 500 mb) per
    forecast soundings and heating will yield weak instability by
    mid-late afternoon. Models continue to show isolated to scattered
    storms late today into the evening. It remains uncertain whether a
    couple of stronger cells will yield a threat of hail beyond a risk
    for small hail. This activity will likely diminish by mid-late
    evening as it moves southeast into central portions of IL/IN.

    ...Central CA...
    Strong cyclonic flow associated with a mid-level low and associated
    trough will move across central CA into the Great Basin during the
    period. Cold temperatures aloft north of the midlevel jet will
    support weak instability over parts of the central valleys. Given
    early precipitation and clouds, as well as marginal low-level shear,
    severe storms appear unlikely. However, a few strong storms may
    occur late in the afternoon if sufficient heating occurs behind the
    early day rain. Small hail appears most probable with the strongest
    cells.

    ..Smith/Thompson.. 04/21/2026

    $$

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  • From COD Weather Processor@1:2320/107 to wx-storm@lists.illinois.edu on Tuesday, April 21, 2026 15:53:48
    ACUS01 KWNS 211553
    SWODY1
    SPC AC 211551

    Day 1 Convective Outlook
    NWS Storm Prediction Center Norman OK
    1051 AM CDT Tue Apr 21 2026

    Valid 211630Z - 221200Z

    ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS THIS AFTERNOON
    OVER THE CA CENTRAL VALLEY...AND OVER PORTIONS OF NORTHERN IL/IN...

    ...SUMMARY...
    Isolated strong thunderstorms are possible in the California Central
    Valley, capable of gusty winds and perhaps a tornado or two. Other
    strong storms are possible in parts of northern IN/IL where gusty
    winds may occur.

    ...Central CA...
    Morning water vapor loop shows a well-defined shortwave trough
    approaching the coast of central CA. An associated mid/upper level
    jet will nose into CA, with forcing for ascent in the left-front
    quadrant of the jet aiding in the development of afternoon/evening thunderstorms over parts of the Central Valley. Forecast soundings
    show steep low and mid level lapse rates and sufficient CAPE for a
    few robust updrafts. Vertical shear will be strong enough for
    supercell structures, including a risk of a tornado or two, small
    hail, and gusty winds.

    ...Northern IN/IL...
    A fast-moving shortwave trough currently over IA/MN will track
    quickly southeastward into WI/IL/IN this afternoon. Visible
    satellite and radar imagery show a line of high-based thunderstorms
    developing ahead of the trough over southern WI. As these storms
    track into northern IL/IN, continued heating/weak destabilization
    will increase the risk of gusty/locally damaging wind gusts and
    small hail in the strongest cores this afternoon.

    ..Hart/Flournoy.. 04/21/2026

    $$

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  • From COD Weather Processor@1:2320/107 to wx-storm@lists.illinois.edu on Tuesday, April 21, 2026 19:49:18
    ACUS01 KWNS 211949
    SWODY1
    SPC AC 211947

    Day 1 Convective Outlook
    NWS Storm Prediction Center Norman OK
    0247 PM CDT Tue Apr 21 2026

    Valid 212000Z - 221200Z

    ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS FOR PORTIONS OF
    THE OHIO VALLEY AND THE CALIFORNIA CENTRAL VALLEY...

    ...SUMMARY...
    Isolated strong thunderstorms are possible in the California Central
    Valley, capable of gusty winds and perhaps a tornado or two. Other
    strong storms are possible over parts of the Great Lakes region.

    ...20Z Update...
    The primary changes to the outlook were to extend Category
    1/Marginal Risk probabilities in CA farther north into the
    Sacramento Valley, and expand severe probabilities in the Great
    Lakes area to include far southwestern Lower MI. In CA, MRMS mosaic
    radar imagery shows convection deepening farther north into the
    Sacramento Valley, and where 19Z mesoanalysis shows well over 100
    J/kg 0-3 km CAPE in place with a focused corridor of low-level
    vertically oriented vorticity. As such, a low-topped supercell could
    develop this afternoon or evening, which may be capable of producing
    hail/wind and perhaps a brief tornado. Thunderstorms, with a history
    of producing marginally severe hail over extreme southeastern WI,
    are currently traversing far southern Lake MI, and have been slow to
    diminish. A corridor of MUCAPE is developing over far southwestern
    Lower MI as 8+ C/km mid-level lapse rates, coinciding with a
    southwesterly WAA regime, overspreads the Great Lakes. Therefore,
    Category 1/Marginal risk wind/hail probabilities were extended
    northeastward into far southwestern Lower MI to account for
    potential strong thunderstorms in this region.

    ..Squitieri.. 04/21/2026

    .PREV DISCUSSION... /ISSUED 1051 AM CDT Tue Apr 21 2026/

    ...Central CA...
    Morning water vapor loop shows a well-defined shortwave trough
    approaching the coast of central CA. An associated mid/upper level
    jet will nose into CA, with forcing for ascent in the left-front
    quadrant of the jet aiding in the development of afternoon/evening thunderstorms over parts of the Central Valley. Forecast soundings
    show steep low and mid level lapse rates and sufficient CAPE for a
    few robust updrafts. Vertical shear will be strong enough for
    supercell structures, including a risk of a tornado or two, small
    hail, and gusty winds.

    ...Northern IN/IL...
    A fast-moving shortwave trough currently over IA/MN will track
    quickly southeastward into WI/IL/IN this afternoon. Visible
    satellite and radar imagery show a line of high-based thunderstorms
    developing ahead of the trough over southern WI. As these storms
    track into northern IL/IN, continued heating/weak destabilization
    will increase the risk of gusty/locally damaging wind gusts and
    small hail in the strongest cores this afternoon.

    $$

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  • From COD Weather Processor@1:2320/107 to wx-storm@lists.illinois.edu on Wednesday, April 22, 2026 00:47:21
    ACUS01 KWNS 220047
    SWODY1
    SPC AC 220045

    Day 1 Convective Outlook
    NWS Storm Prediction Center Norman OK
    0745 PM CDT Tue Apr 21 2026

    Valid 220100Z - 221200Z

    ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF
    THE SAN JOAQUIN VALLEY OF CENTRAL CALIFORNIA...

    ...SUMMARY...
    Isolated strong thunderstorms are possible in the San Joaquin Valley
    of central California early this evening, capable of isolated severe
    gusts and perhaps a tornado.

    ...San Joaquin Valley...
    Latest water vapor imagery shows an upper-level low just off the
    coast of far northern California. A mid-level jet is wrapped around
    the southern edge of the system. Within the left exit region of the
    mid-level jet, a couple of strong to severe thunderstorms are
    ongoing in the San Joaquin Valley. Strong lift is present along the
    northern gradient of the mid-level jet, which is coincident with a
    pocket of instability, with the RAP showing MLCAPE in the 250 to 500
    J/kg range. Over this area, the mid-level jet is creating deep-layer
    shear exceeding 85 knots. This environment will continue support a
    marginal severe threat. Isolated severe wind gusts and perhaps a
    tornado will be possible for another hour this evening.

    ..Broyles.. 04/22/2026

    $$

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  • From COD Weather Processor@1:2320/107 to wx-storm@lists.illinois.edu on Wednesday, April 22, 2026 05:55:53
    ACUS01 KWNS 220555
    SWODY1
    SPC AC 220554

    Day 1 Convective Outlook
    NWS Storm Prediction Center Norman OK
    1254 AM CDT Wed Apr 22 2026

    Valid 221200Z - 231200Z

    ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF
    THE HIGH PLAINS AND FROM NORTHEAST INDIANA INTO CENTRAL AND NORTHERN
    OHIO...

    ...SUMMARY...
    Severe thunderstorms with hail and isolated severe gusts will be
    possible across parts of the High Plains this afternoon and evening.
    Isolated severe gusts and hail will also be possible in parts of
    northeast Indiana and Ohio.

    ...High Plains...
    At mid-levels today, heights will fall across much of the High
    Plains, as a ridge moves toward the Mississippi Valley and a trough
    moves through the Intermountain West. In response, a lee trough will
    sharpen across the High Plains. To the east of the surface trough,
    moisture advection will take place. Surface dewpoints will increase
    into the 55 to 60 F range to the east of a well-developed dryline
    extending from west Texas northward into southwest Nebraska.
    Although large-scale ascent will be weak along the dryline,
    low-level convergence will aid isolated convective initiation during
    the mid to late afternoon. The most favorable location for storm
    development will be from northwest Kansas into west-central Nebraska
    and southern South Dakota, as the low-level jet strengthens in the
    late afternoon and early evening. In addition to moderate
    instability, 0-6 km shear is forecast to increase into the 35 to 40
    knot range by early evening. This, combined with 700-500 mb lapse
    rates in the 8.5 to 9 C/km range should be favorable for supercells
    with isolated large hail, with the greatest potential from northwest
    Kansas into west-central Nebraska. A few severe wind gusts may also
    occur from western Kansas into South Dakota.

    Further south into west Texas and the Oklahoma Panhandle, the lift
    supportive of convective development will be confined to weak
    low-level convergence along the dryline. If a storm can initiate,
    then a supercell could develop with potential for large hail.

    ...Northeast Indiana/Central and Northern Ohio...
    A mid-level ridge will move into the upper Mississippi Valley today,
    as northwesterly mid-level flow persists over the Great Lakes
    region. At the surface, a slow-moving front will remain in place
    from southern Wisconsin eastward into southern Michigan. Scattered thunderstorms will develop this afternoon along and to the south of
    the front as surface temperatures warm and low-level convergence
    increases. Model forecasts in the mid to late afternoon from
    northeast Indiana into central and northern Ohio have MLCAPE in the
    2000 to 2500 J/kg range, with 0-3 km lapse rates near 8.5 C/km. In
    addition, 0-6 km shear is forecast to approach 30 knots, which could
    be enough for a marginal severe threat. Isolated severe gusts and
    hail will be possible with the stronger multicells in areas that
    destabilize the most.

    ..Broyles/Chalmers.. 04/22/2026

    $$

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  • From COD Weather Processor@1:2320/107 to wx-storm@lists.illinois.edu on Wednesday, April 22, 2026 12:39:29
    ACUS01 KWNS 221239
    SWODY1
    SPC AC 221237

    Day 1 Convective Outlook
    NWS Storm Prediction Center Norman OK
    0737 AM CDT Wed Apr 22 2026

    Valid 221300Z - 231200Z

    ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS THIS
    AFTERNOON/EVENING FOR PARTS OF THE HIGH PLAINS/NORTHERN PLAINS...AND
    FROM NORTHEAST INDIANA INTO NORTHERN OHIO...

    ...SUMMARY...
    Isolated strong-severe thunderstorms with strong gusts and hail will
    be possible across parts of the High Plains this afternoon and
    evening, as well as from northeast Indiana into northern Ohio.

    ...High Plains this afternoon/evening...
    In response to a shortwave trough digging south-southeastward over
    BC/AB, a closed low over the Great Basin will evolve into a more
    open wave and eject northeastward to the northern High Plains by
    early Thursday. An associated, deep lee cyclone will develop
    eastward from MT to near the ND/SK border, with a lee trough
    extending southward into the central/southern High Plains. East of
    the lee trough, low-level moisture (boundary-layer dewpoints in the
    55-60 F range) will spread northward today from TX/OK to KS/NE.
    Diurnal mixing will likely limit the quality of the moisture farther
    north into the Dakotas. Thus, a few high-based thunderstorms will
    be possible this afternoon/evening from NE into SD along the lee
    trough with deep mixing, where inverted-v profiles will favor strong
    outflow gusts.

    A narrow zone of moderate buoyancy is expected along the dryline
    from southwest NE and western KS into west TX, where deep-layer
    vertical shear will be sufficient for supercells. Only limited
    height falls and a warm elevated mixed layer, in combination with
    somewhat limited parcel residence times in the dryline circulation,
    suggest that storm coverage will be isolated at best. There will be
    a conditional threat for isolated large hail with any sustained
    storms.

    ...Dakotas tonight...
    The threat for thunderstorms may increase tonight as a result of
    ascent preceding the midlevel trough, and a modest increase in
    low-level moisture with a strengthening low-level jet. Much of the
    convection will likely be rooted above the surface, but could still
    produce strong outflow gusts and marginally severe hail.

    ...IN/OH this afternoon/evening...
    Residual low-level moisture and surface heating along a diffuse
    baroclinic zone will support thunderstorm development this afternoon
    from northeast IN into northern OH. Though deep-layer wind profiles
    will not be particularly strong, relatively cool midlevel
    temperatures and weak-moderate buoyancy could support marginally
    severe hail and gusty outflow winds with the strongest storms.

    ..Thompson/Bentley.. 04/22/2026

    $$

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  • From COD Weather Processor@1:2320/107 to wx-storm@lists.illinois.edu on Wednesday, April 22, 2026 16:30:27
    ACUS01 KWNS 221630
    SWODY1
    SPC AC 221628

    Day 1 Convective Outlook
    NWS Storm Prediction Center Norman OK
    1128 AM CDT Wed Apr 22 2026

    Valid 221630Z - 231200Z

    ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS THIS
    AFTERNOON/EVENING FOR PARTS OF THE HIGH PLAINS/NORTHERN PLAINS...AND
    ACROSS FAR SOUTHERN LOWER MICHIGAN...NORTHEAST INDIANA INTO NORTHERN
    OHIO...

    ...SUMMARY...
    Isolated strong-severe thunderstorms with strong gusts and hail will
    be possible across parts of the High Plains this afternoon and
    evening, as well as from northeast Indiana into northern Ohio.

    ...Synopsis...
    Recent surface analysis shows an airmass modifying under low-level
    moisture advection across the southern and central Plains, with mid
    50s dewpoints reaching through central KS and into eastern
    NE/western IA. This moderate low-level moisture also extends
    eastward from IA into northern IL and IN, just south of a stationary
    boundary that demarcates a drier, more stable airmass across much of
    the Great Lakes from the modifying airmass farther south/southwest.

    This analysis also reveals a pair of surface lows, one over
    north-central MT and the other over far northeast WY/far southeast
    MT, linked by modest surface troughing. A wavy surface trough also
    extends southward to another low over southeast CO. Thunderstorm
    development is anticipated today/tonight near these lows and their
    related surface boundaries. In particular, strong to isolated severe thunderstorms appear possible near the northeast WY/far southeast MT
    low as it moves eastward across SD, as well as in the vicinity of
    the stationary boundary across northern IN and OH.

    ...IN/OH...
    Weak surface low over southern Lower MI has already contributed to
    thunderstorm development. The airmass downstream of this low, and
    south of the stationary boundary that extends east-to-west near the
    MI and IN/OH border vicinity, will likely destabilize throughout the
    day amid continued low-level moisture advection and strong diurnal
    heating. This destabilization coupled with low-level convergence
    near the low and boundary will support increasing thunderstorm
    coverage. Deep-layer wind profiles will be modest, but cool
    mid-level temperatures and weak-moderate buoyancy could support
    isolated severe hail and gusty outflow winds with the strongest
    storms.

    ...High Plains...
    Primary surface low over central MT is forecast to deepen today as a
    closed upper low currently over the Great Basin ejects northeastward
    while evolving towards a more open wave. At the same time, a
    secondary surface low (currently over far northeast WY/far southeast
    MT) is forecast to move eastward across SD, interacting with the
    modifying airmass across the northern/central Plains. Expectation is
    for this airmass to be deeply mixed, with perhaps some minimal
    buoyancy atop the well-mixed boundary layer. Development of a few
    high-based thunderstorms is possible this afternoon/evening from NE
    into SD, as well as northeast MT, along the trough where deep mixing
    and inverted-v profiles will favor strong outflow gusts.

    Farther south, an even more conditional risk is anticipated along a
    sharpening dryline from southwest NE and western KS into west TX.
    Given the limited large-scale forcing and only weak low-level
    convergence, warm mid-level temperatures and related capping
    associated with a notable elevated mixed layer will likely suppress thunderstorm development. Here, deep-layer vertical shear will be
    sufficient for supercells, and a conditional risk for large hail and
    strong gusts exists with any updrafts that are able to persist and
    mature.

    ...Western/Central NE into the Dakotas...
    Additional thunderstorms are possible tonight from western/central
    NE into the Dakotas as an eastward-progressing cold front interacts
    with low-level moisture continuing to advect northward across the
    Plains and a strengthening low-level jet. These storms will likely
    be elevated behind the front, with some isolated hail possible early
    in the convective cycle. Additionally, mid-level dry air will likely
    remain across the region, supporting the potential for strong
    outflow gusts despite the storms elevated character.

    ..Mosier/Lyons.. 04/22/2026

    $$

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  • From COD Weather Processor@1:2320/107 to wx-storm@lists.illinois.edu on Wednesday, April 22, 2026 19:53:29
    ACUS01 KWNS 221953
    SWODY1
    SPC AC 221951

    Day 1 Convective Outlook
    NWS Storm Prediction Center Norman OK
    0251 PM CDT Wed Apr 22 2026

    Valid 222000Z - 231200Z

    ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS FOR PORTIONS OF
    THE HIGH PLAINS INTO THE NORTHERN PLAINS AND EASTERN PARTS OF THE
    OHIO VALLEY...

    ...SUMMARY...
    Isolated strong-severe thunderstorms with strong gusts and hail will
    be possible across parts of the High Plains this afternoon and
    evening, as well as from northeast Indiana into northern Ohio.

    ...20Z Update...
    The previous forecast (see below) remains on track, with mainly
    minor adjustments made to the general thunder and severe
    probabilities to reflect the latest observations and guidance
    consensus.

    ..Squitieri/Mosier.. 04/22/2026

    .PREV DISCUSSION... /ISSUED 1128 AM CDT Wed Apr 22 2026/

    ...Synopsis...
    Recent surface analysis shows an airmass modifying under low-level
    moisture advection across the southern and central Plains, with mid
    50s dewpoints reaching through central KS and into eastern
    NE/western IA. This moderate low-level moisture also extends
    eastward from IA into northern IL and IN, just south of a stationary
    boundary that demarcates a drier, more stable airmass across much of
    the Great Lakes from the modifying airmass farther south/southwest.

    This analysis also reveals a pair of surface lows, one over
    north-central MT and the other over far northeast WY/far southeast
    MT, linked by modest surface troughing. A wavy surface trough also
    extends southward to another low over southeast CO. Thunderstorm
    development is anticipated today/tonight near these lows and their
    related surface boundaries. In particular, strong to isolated severe thunderstorms appear possible near the northeast WY/far southeast MT
    low as it moves eastward across SD, as well as in the vicinity of
    the stationary boundary across northern IN and OH.

    ...IN/OH...
    Weak surface low over southern Lower MI has already contributed to
    thunderstorm development. The airmass downstream of this low, and
    south of the stationary boundary that extends east-to-west near the
    MI and IN/OH border vicinity, will likely destabilize throughout the
    day amid continued low-level moisture advection and strong diurnal
    heating. This destabilization coupled with low-level convergence
    near the low and boundary will support increasing thunderstorm
    coverage. Deep-layer wind profiles will be modest, but cool
    mid-level temperatures and weak-moderate buoyancy could support
    isolated severe hail and gusty outflow winds with the strongest
    storms.

    ...High Plains...
    Primary surface low over central MT is forecast to deepen today as a
    closed upper low currently over the Great Basin ejects northeastward
    while evolving towards a more open wave. At the same time, a
    secondary surface low (currently over far northeast WY/far southeast
    MT) is forecast to move eastward across SD, interacting with the
    modifying airmass across the northern/central Plains. Expectation is
    for this airmass to be deeply mixed, with perhaps some minimal
    buoyancy atop the well-mixed boundary layer. Development of a few
    high-based thunderstorms is possible this afternoon/evening from NE
    into SD, as well as northeast MT, along the trough where deep mixing
    and inverted-v profiles will favor strong outflow gusts.

    Farther south, an even more conditional risk is anticipated along a
    sharpening dryline from southwest NE and western KS into west TX.
    Given the limited large-scale forcing and only weak low-level
    convergence, warm mid-level temperatures and related capping
    associated with a notable elevated mixed layer will likely suppress thunderstorm development. Here, deep-layer vertical shear will be
    sufficient for supercells, and a conditional risk for large hail and
    strong gusts exists with any updrafts that are able to persist and
    mature.

    ...Western/Central NE into the Dakotas...
    Additional thunderstorms are possible tonight from western/central
    NE into the Dakotas as an eastward-progressing cold front interacts
    with low-level moisture continuing to advect northward across the
    Plains and a strengthening low-level jet. These storms will likely
    be elevated behind the front, with some isolated hail possible early
    in the convective cycle. Additionally, mid-level dry air will likely
    remain across the region, supporting the potential for strong
    outflow gusts despite the storms elevated character.

    $$

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  • From COD Weather Processor@1:2320/107 to wx-storm@lists.illinois.edu on Thursday, April 23, 2026 00:30:03
    ACUS01 KWNS 230029
    SWODY1
    SPC AC 230028

    Day 1 Convective Outlook
    NWS Storm Prediction Center Norman OK
    0728 PM CDT Wed Apr 22 2026

    Valid 230100Z - 231200Z

    ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF
    THE CENTRAL AND NORTHERN PLAINS...

    ...SUMMARY...
    Thunderstorms with isolated severe gusts and hail will be possible
    across parts of the central and northern Plains this evening into
    tonight.

    ...Central and Northern Plains...
    Water vapor imagery shows a mid-level low over the northern Rockies,
    with cyclonic southwesterly flow located from the Desert Southwest
    into the northern Plains. At the surface, a north-to-south oriented
    trough is present across the High Plains. Isolated to scattered
    thunderstorms are ongoing to the east of the trough from northwest
    Nebraska into west-central South Dakota. Additional storms are
    ongoing in northeastern Montana to the west of a surface low. As the
    low-level jet strengthens across the region tonight, continued
    thunderstorm development is expected. A hail and wind-damage threat
    will be possible along and near an axis of weak instability from
    west-central Nebraska into far southern North Dakota. A wind-damage
    threat will also be possible with storms currently ongoing in
    northeast Montana.

    ..Broyles.. 04/23/2026

    $$

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  • From COD Weather Processor@1:2320/107 to wx-storm@lists.illinois.edu on Thursday, April 23, 2026 05:04:01
    ACUS01 KWNS 230503
    SWODY1
    SPC AC 230502

    Day 1 Convective Outlook
    NWS Storm Prediction Center Norman OK
    1202 AM CDT Thu Apr 23 2026

    Valid 231200Z - 241200Z

    ...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF
    EASTERN KANSAS...

    ...SUMMARY...
    Severe thunderstorms are expected to develop this afternoon and
    evening from the southern and central Plains into the lower to mid
    Missouri Valley, and upper Mississippi Valley. Tornadoes, large hail
    and severe wind gusts will be possible.

    ...Southern and Central Plains/Lower to Mid Missouri Valley/Upper
    Mississippi Valley...
    An upper-level trough will move through the central Rockies this
    morning, and into the High Plains this afternoon as a 50 to 60 knot
    mid-level jet moves into the Great Plains. At the surface, a cold
    front will advance southeastward into the mid Missouri Valley and
    central Plains. Moisture advection ahead of the front will increase
    surface dewpoints into the mid 60s F by afternoon. This will
    contribute to moderate destabilization as surface temperatures warm
    along the moist axis. Thunderstorms are first expected to develop
    ahead of the front over the mid Missouri and upper Mississippi
    Valleys in the early to mid afternoon. Convective coverage will
    rapidly expand southward into eastern Kansas by late afternoon, and
    into far northern Oklahoma during the early to mid evening. MCS
    development appears likely to take place along and ahead of the
    front.

    The best environment for severe storms will be in eastern Kansas. In
    this area, RAP forecast soundings late this afternoon ahead of the
    front have MLCAPE peaking just above 3000 J/kg, with 700-500 mb
    lapse rates in the 7.5 to 8 C/km range. 0-6 km shear is forecast to
    be in the 35 to 40 knot range. This environment will support
    supercells with large hail. Hailstones greater than 2 inches in
    diameter will be possible with the more intense supercells. In
    addition, 0-3 km storm-relative helicity is forecast to increase
    into the 300 to 400 m2/s2 range by 00Z, as at 40 to 50 knot
    low-level jet strengthens. This will support tornadoes with
    supercells. Supercells will initially be discrete but a line is
    expected to form by early evening. As the line forms, rotating cells
    within the line should also be capable of producing tornadoes. A
    strong tornado or two will be possible late this afternoon and early
    this evening. A wind-damage threat is also expected to develop. The
    southern edge of the line will impact far northern Oklahoma in the
    early to mid evening. Convective coverage should be isolated further
    south across the rest of Oklahoma.

    Further north-northeast into Iowa and southern Minnesota,
    instability will not be as strong. RAP forecast soundings by late
    afternoon have MLCAPE peaking in the 1500 to 2000 J/kg range. This,
    combined with 30 to 35 knots of deep-layer shear and 700-500 mb
    lapse rates of 7 to 7.5 C/km should support large hail with
    supercells. Supercells and developing line segments should also be
    capable of producing wind damage, hail and a tornado or two.

    ..Broyles/Chalmers.. 04/23/2026

    $$

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  • From COD Weather Processor@1:2320/107 to wx-storm@lists.illinois.edu on Thursday, April 23, 2026 12:52:05
    ACUS01 KWNS 231251
    SWODY1
    SPC AC 231250

    Day 1 Convective Outlook
    NWS Storm Prediction Center Norman OK
    0750 AM CDT Thu Apr 23 2026

    Valid 231300Z - 241200Z

    ...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS LATER THIS AFTERNOON/EVENING FOR EASTERN KANSAS INTO EXTREME NORTHERN
    OKLAHOMA...

    ...SUMMARY...
    Severe thunderstorms are expected to develop this afternoon and
    evening from the southern and central Plains into the lower to mid
    Missouri Valley, and upper Mississippi Valley. Tornadoes, large hail
    and severe wind gusts will be possible.

    ...MN/IA to KS/northern OK this afternoon into tonight...
    The interaction of a southeastward moving midlevel trough over
    southern BC/AB and a northeastward moving trough over the western
    Dakotas will lead to the formation of a deep closed low over
    southern SK. An associated, occluding surface cyclone will weaken
    across southern MB by this evening, as a trailing cold front moves
    across MN/IA/KS/MO and northern OK. Low-level moisture will spread
    northward across IA/MN in advance of the cold front, beneath the
    northeast edge of an elevated mixed layer. Surface heating and the
    degree of buoyancy may be limited by extensive clouds from IA into
    MN, and forecast wind profiles show complex/messy hodographs
    structures (stronger low-level shear lingering across IA). Mixed
    convective modes are expected along and ahead of the front this
    afternoon, which could produce occasional wind damage, large hail
    and perhaps a couple of tornadoes.

    The more substantial severe threat is expected late this afternoon
    through late evening from eastern KS into far northern OK, near and
    just northeast of a cold front/dryline triple point and weak
    secondary cyclone. A midlevel speed max near the Four Corners will
    progress eastward to the TX Panhandle by this evening, with ascent
    in the left exit region of the jet coincident with the triple point
    near or just north of the KS/OK border. An influx of mid 60s
    boundary-layer dewpoints beneath steep midlevel lapse rates will
    contribute to MLCAPE of 2000-3000 J/kg, with weakening convective
    inhibition across KS by mid afternoon.

    Storm development is expected along the cold front in KS by mid
    afternoon, with storms expected to develop southward to near the
    triple point. The large buoyancy, steep midlevel lapse rates and
    deep-layer shear sufficient for supercells will favor very large
    hail (2-3 inches in diameter) with the initial/more discrete storms.
    The tornado threat will peak this evening as low-level
    shear/hodograph curvature increase near the KS/OK border - there
    will be strong tornado potential with the anchor/southern supercells
    near the triple point. Upscale storm growth and cold pool
    development will favor a more linear convective mode with occasional
    wind damage as the outflow/effective cold front spreads
    southeastward into northeast OK and southwest MO overnight.

    ...OK dryline this evening...
    Storm development along the dryline in OK is uncertain late this afternoon/evening. Forecast soundings suggest that the degree of
    surface heating/mixing along the dryline and residence time in the
    dryline circulation will be close to supporting deep convection. If
    storms do form, the environment will conditionally favor very large
    hail initially, and the possibility of an evening tornado threat
    with any sustained storm.

    ..Thompson/Bentley.. 04/23/2026

    $$

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  • From COD Weather Processor@1:2320/107 to wx-storm@lists.illinois.edu on Thursday, April 23, 2026 16:15:25
    ACUS01 KWNS 231615
    SWODY1
    SPC AC 231615

    Day 1 Convective Outlook
    NWS Storm Prediction Center Norman OK
    Issued by 15th OWS Scott Air Force Base IL
    1115 AM CDT Thu Apr 23 2026

    Valid 231630Z - 241200Z

    ...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS EASTERN
    KANSAS...NORTHERN OKLAHOMA...

    ...SUMMARY...
    Severe thunderstorms are expected to develop this afternoon and
    evening from the southern and central Plains into the lower to mid
    Missouri Valley, and upper Mississippi Valley. Tornadoes, large hail
    and severe wind gusts will be possible.

    ...MN/IA to KS/northern OK this afternoon into tonight...
    The interaction of a southeastward moving midlevel trough over
    southern BC/AB and a northeastward moving trough over the western
    Dakotas will lead to the formation of a deep closed low over
    southern SK. An associated, occluding surface cyclone will weaken
    across southern MB by this evening, as a trailing cold front moves
    across MN/IA/KS/MO and northern OK. Low-level moisture will spread
    northward across IA/MN in advance of the cold front, beneath the
    northeast edge of an elevated mixed layer. Surface heating and the
    degree of buoyancy may be limited by extensive clouds from IA into
    MN, and forecast wind profiles show complex/messy hodographs
    structures (stronger low-level shear lingering across IA). Mixed
    convective modes are expected along and ahead of the front this
    afternoon, which could produce occasional wind damage, large hail
    and perhaps a couple of tornadoes.

    The more substantial severe threat is expected late this afternoon
    through late evening from eastern KS into northern OK, near and just
    northeast of a cold front/dryline triple point and weak secondary
    cyclone. A midlevel speed max near the Four Corners will progress
    eastward to the TX Panhandle by this evening, with ascent in the
    left exit region of the jet coincident with the triple point near or
    just north of the KS/OK border. An influx of mid 60s boundary-layer
    dewpoints beneath steep midlevel lapse rates will contribute to
    MLCAPE of 2000-3000 J/kg, with weakening convective inhibition
    across KS by mid afternoon.

    Storm development is expected along the cold front in KS by mid
    afternoon, with storms expected to develop southward to near the
    triple point. The large buoyancy, steep midlevel lapse rates and
    deep-layer shear sufficient for supercells will favor very large
    hail (2-3 inches in diameter) with the initial/more discrete storms.
    The tornado threat will peak this evening as low-level
    shear/hodograph curvature increase near the KS/OK border - there
    will be strong tornado potential with the anchor/southern supercells
    near the triple point. Upscale storm growth and cold pool
    development will favor a more linear convective mode with occasional
    wind damage as the outflow/effective cold front spreads
    southeastward into northeast OK and southwest MO overnight.

    ...OK dryline this evening...
    Storm development along the dryline in OK is uncertain late this afternoon/evening. Forecast soundings suggest that the degree of
    surface heating/mixing along the dryline and residence time in the
    dryline circulation will be close to supporting deep convection. If
    storms do form, the environment will conditionally favor very large
    hail initially, and the possibility of an evening tornado threat
    with any sustained storm.

    ..Afwa.. 04/23/2026

    $$

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  • From COD Weather Processor@1:2320/107 to wx-storm@lists.illinois.edu on Thursday, April 23, 2026 16:51:37
    ACUS01 KWNS 231651
    SWODY1
    SPC AC 231615

    Day 1 Convective Outlook
    NWS Storm Prediction Center Norman OK
    Issued by 15th OWS Scott Air Force Base IL
    1115 AM CDT Thu Apr 23 2026

    Valid 231630Z - 241200Z

    ...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS EASTERN
    KANSAS...NORTHERN OKLAHOMA...

    ...SUMMARY...
    Severe thunderstorms are expected to develop this afternoon and
    evening from the southern and central Plains into the lower to mid
    Missouri Valley, and upper Mississippi Valley. Tornadoes, large hail
    and severe wind gusts will be possible.

    ...MN/IA to KS/northern OK this afternoon into tonight...
    The interaction of a southeastward moving midlevel trough over
    southern BC/AB and a northeastward moving trough over the western
    Dakotas will lead to the formation of a deep closed low over
    southern SK. An associated, occluding surface cyclone will weaken
    across southern MB by this evening, as a trailing cold front moves
    across MN/IA/KS/MO and northern OK. Low-level moisture will spread
    northward across IA/MN in advance of the cold front, beneath the
    northeast edge of an elevated mixed layer. Surface heating and the
    degree of buoyancy may be limited by extensive clouds from IA into
    MN, and forecast wind profiles show complex/messy hodographs
    structures (stronger low-level shear lingering across IA). Mixed
    convective modes are expected along and ahead of the front this
    afternoon, which could produce occasional wind damage, large hail
    and perhaps a couple of tornadoes.

    The more substantial severe threat is expected late this afternoon
    through late evening from eastern KS into northern OK, near and just
    northeast of a cold front/dryline triple point and weak secondary
    cyclone. A midlevel speed max near the Four Corners will progress
    eastward to the TX Panhandle by this evening, with ascent in the
    left exit region of the jet coincident with the triple point near or
    just north of the KS/OK border. An influx of mid 60s boundary-layer
    dewpoints beneath steep midlevel lapse rates will contribute to
    MLCAPE of 2000-3000 J/kg, with weakening convective inhibition
    across KS by mid afternoon.

    Storm development is expected along the cold front in KS by mid
    afternoon, with storms expected to develop southward to near the
    triple point. The large buoyancy, steep midlevel lapse rates and
    deep-layer shear sufficient for supercells will favor very large
    hail (2-3 inches in diameter) with the initial/more discrete storms.
    The tornado threat will peak this evening as low-level
    shear/hodograph curvature increase near the KS/OK border - there
    will be strong tornado potential with the anchor/southern supercells
    near the triple point. Upscale storm growth and cold pool
    development will favor a more linear convective mode with occasional
    wind damage as the outflow/effective cold front spreads
    southeastward into northeast OK and southwest MO overnight.

    ...OK dryline this evening...
    Storm development along the dryline in OK is uncertain late this afternoon/evening. Forecast soundings suggest that the degree of
    surface heating/mixing along the dryline and residence time in the
    dryline circulation will be close to supporting deep convection. If
    storms do form, the environment will conditionally favor very large
    hail initially, and the possibility of an evening tornado threat
    with any sustained storm.

    ..Afwa.. 04/23/2026

    $$

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  • From COD Weather Processor@1:2320/107 to wx-storm@lists.illinois.edu on Thursday, April 23, 2026 19:45:32
    ACUS01 KWNS 231945
    SWODY1
    SPC AC 231945

    Day 1 Convective Outlook
    NWS Storm Prediction Center Norman OK
    Issued by 15th OWS Scott Air Force Base IL
    0245 PM CDT Thu Apr 23 2026

    Valid 232000Z - 241200Z

    ...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS NORTH CENTRAL MINNESOTA...EASTERN KANSAS...NORTHERN OKLAHOMA...

    ...SUMMARY...
    Severe thunderstorms are expected to develop this afternoon and
    evening from the southern through central Plains and Minnesota into
    the lower to mid Missouri Valley, and upper Mississippi Valley.
    Tornadoes, large hail and severe wind gusts will be possible.

    ...MN/IA to KS/northern OK this afternoon into tonight...
    The interaction of a southeastward moving midlevel trough over
    southern BC/AB and a northeastward moving trough over the western
    Dakotas will lead to the formation of a deep closed low over
    southern SK. An associated, occluding surface cyclone will weaken
    across southern MB by this evening, as a trailing cold front moves
    across MN/IA/KS/MO and northern OK. Low-level moisture will spread
    northward across IA/MN in advance of the cold front, beneath the
    northeast edge of an elevated mixed layer. Surface heating and the
    degree of buoyancy may be limited by extensive clouds from IA into
    MN, and forecast wind profiles show complex/messy hodographs
    structures (stronger low-level shear lingering across IA). Mixed
    convective modes are expected along and ahead of the front this
    afternoon, which could produce occasional wind damage, large hail
    and perhaps a couple of tornadoes.

    The more substantial severe threat is expected late this afternoon
    through late evening from eastern KS into northern OK, near and just
    northeast of a cold front/dryline triple point and weak secondary
    cyclone. A midlevel speed max near the Four Corners will progress
    eastward to the TX Panhandle by this evening, with ascent in the
    left exit region of the jet coincident with the triple point near or
    just north of the KS/OK border. An influx of mid 60s boundary-layer
    dewpoints beneath steep midlevel lapse rates will contribute to
    MLCAPE of 2000-3000 J/kg, with weakening convective inhibition
    across KS by mid afternoon.

    Storm development is expected along the cold front in KS by mid
    afternoon, with storms expected to develop southward to near the
    triple point. The large buoyancy, steep midlevel lapse rates and
    deep-layer shear sufficient for supercells will favor very large
    hail (2-3 inches in diameter) with the initial/more discrete storms.
    The tornado threat will peak this evening as low-level
    shear/hodograph curvature increase near the KS/OK border - there
    will be strong tornado potential with the anchor/southern supercells
    near the triple point. Upscale storm growth and cold pool
    development will favor a more linear convective mode with occasional
    wind damage as the outflow/effective cold front spreads
    southeastward into northeast OK and southwest MO overnight.

    ...OK dryline this evening...
    Storm development along the dryline in OK is uncertain late this afternoon/evening. Forecast soundings suggest that the degree of
    surface heating/mixing along the dryline and residence time in the
    dryline circulation will be close to supporting deep convection. If
    storms do form, the environment will conditionally favor very large
    hail initially, and the possibility of an evening tornado threat
    with any sustained storm.

    ..Afwa.. 04/23/2026

    $$

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  • From COD Weather Processor@1:2320/107 to wx-storm@lists.illinois.edu on Thursday, April 23, 2026 20:24:38
    ACUS01 KWNS 232024
    SWODY1
    SPC AC 231945

    Day 1 Convective Outlook
    NWS Storm Prediction Center Norman OK
    Issued by 15th OWS Scott Air Force Base IL
    0245 PM CDT Thu Apr 23 2026

    Valid 232000Z - 241200Z

    ...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS NORTH CENTRAL MINNESOTA...EASTERN KANSAS...NORTHERN OKLAHOMA...

    ...SUMMARY...
    Severe thunderstorms are expected to develop this afternoon and
    evening from the southern through central Plains and Minnesota into
    the lower to mid Missouri Valley, and upper Mississippi Valley.
    Tornadoes, large hail and severe wind gusts will be possible.

    ...MN/IA to KS/northern OK this afternoon into tonight...
    The interaction of a southeastward moving midlevel trough over
    southern BC/AB and a northeastward moving trough over the western
    Dakotas will lead to the formation of a deep closed low over
    southern SK. An associated, occluding surface cyclone will weaken
    across southern MB by this evening, as a trailing cold front moves
    across MN/IA/KS/MO and northern OK. Low-level moisture will spread
    northward across IA/MN in advance of the cold front, beneath the
    northeast edge of an elevated mixed layer. Surface heating and the
    degree of buoyancy may be limited by extensive clouds from IA into
    MN, and forecast wind profiles show complex/messy hodographs
    structures (stronger low-level shear lingering across IA). Mixed
    convective modes are expected along and ahead of the front this
    afternoon, which could produce occasional wind damage, large hail
    and perhaps a couple of tornadoes.

    The more substantial severe threat is expected late this afternoon
    through late evening from eastern KS into northern OK, near and just
    northeast of a cold front/dryline triple point and weak secondary
    cyclone. A midlevel speed max near the Four Corners will progress
    eastward to the TX Panhandle by this evening, with ascent in the
    left exit region of the jet coincident with the triple point near or
    just north of the KS/OK border. An influx of mid 60s boundary-layer
    dewpoints beneath steep midlevel lapse rates will contribute to
    MLCAPE of 2000-3000 J/kg, with weakening convective inhibition
    across KS by mid afternoon.

    Storm development is expected along the cold front in KS by mid
    afternoon, with storms expected to develop southward to near the
    triple point. The large buoyancy, steep midlevel lapse rates and
    deep-layer shear sufficient for supercells will favor very large
    hail (2-3 inches in diameter) with the initial/more discrete storms.
    The tornado threat will peak this evening as low-level
    shear/hodograph curvature increase near the KS/OK border - there
    will be strong tornado potential with the anchor/southern supercells
    near the triple point. Upscale storm growth and cold pool
    development will favor a more linear convective mode with occasional
    wind damage as the outflow/effective cold front spreads
    southeastward into northeast OK and southwest MO overnight.

    ...OK dryline this evening...
    Storm development along the dryline in OK is uncertain late this afternoon/evening. Forecast soundings suggest that the degree of
    surface heating/mixing along the dryline and residence time in the
    dryline circulation will be close to supporting deep convection. If
    storms do form, the environment will conditionally favor very large
    hail initially, and the possibility of an evening tornado threat
    with any sustained storm.

    ..Afwa.. 04/23/2026

    $$

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  • From COD Weather Processor@1:2320/107 to wx-storm@lists.illinois.edu on Friday, April 24, 2026 01:01:08
    ACUS01 KWNS 240101
    SWODY1
    SPC AC 240059

    Day 1 Convective Outlook
    NWS Storm Prediction Center Norman OK
    0759 PM CDT Thu Apr 23 2026

    Valid 240100Z - 241200Z

    ...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS ACROSS ARTS OF
    EASTERN KANSAS AND NORTHERN OKLAHOMA...

    ...SUMMARY...
    Scattered severe thunderstorms will continue this evening from parts
    of the southern and central Plains north-northeastward into the
    lower Missouri and upper Mississippi Valleys. Tornadoes, large hail
    and severe wind gusts are expected.

    ...Southern and Central Plains...
    Latest water vapor imagery shows an upper-level trough over the
    Great Plains, with an associated mid-level jet streak moving through
    the base of the trough into the southern Plains. At the surface, a
    cold front is advancing southeastward across far southeast Nebraska, east-central Kansas and far northern Oklahoma. Ahead of the front,
    multiple line segments are ongoing. These broken lines are embedded
    with discrete to semi-discrete supercells. The storms are located
    along an axis of moderate to strong instability, with the RAP
    showing MLCAPE in the 2500 to 3500 J/kg range. Over the top of this
    moist and unstable airmass, flow is westerly around 50 knots. This
    is creating moderate to strong deep-layer shear which will continue
    to support supercells this evening. Steep mid-level lapse rates
    approaching 8 C/km will be favorable for large hail. In addition,
    the western edge of a 40 to 50 knot low-level jet will remain in
    place over eastern Kansas. WSR-88D VWPs that are sampling the
    low-level jet have 0-3 km storm-relative helicity in the 400 to 450
    m2/s2 range, which will support a continued tornado threat. In
    addition, a threat for wind damage will also continue through the
    mid to late evening...see MCD 510.

    ...Lower Missouri Valley/Upper Mississippi Valley...
    Southwesterly mid-level flow is in place over much of the
    north-central U.S. At the surface, a cold front is located from
    central Minnesota south-southwestward into the mid Missouri Valley.
    A line of strong to severe thunderstorms is ongoing ahead of the
    front from far southeastern Minnesota into central Iowa and far
    northwestern Missouri. Moderate instability is analyzed ahead of the
    line, with the RAP showing MLCAPE in the 1500 to 2000 J/kg range.
    The thermodynamic environment will continue to be favorable for
    isolated large hail. In addition, a 40 to 50 knot jet is analyzed
    over east-central Iowa. As the low-level jet strengthens, tornadoes
    will be possible with rotating cells embedded in the line. As the
    line continues to move eastward through the mid to late evening,
    wind damage will be possible with embedded supercells and bowing
    line segments.

    ..Broyles.. 04/24/2026

    $$

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  • From COD Weather Processor@1:2320/107 to wx-storm@lists.illinois.edu on Friday, April 24, 2026 05:54:10
    ACUS01 KWNS 240554
    SWODY1
    SPC AC 240552

    Day 1 Convective Outlook
    NWS Storm Prediction Center Norman OK
    1252 AM CDT Fri Apr 24 2026

    Valid 241200Z - 251200Z

    ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF
    THE SOUTHERN PLAINS...ARK-LA-TEX AND LOWER MISSISSIPPI VALLEY...

    ...SUMMARY...
    Scattered severe thunderstorms are expected today from the Southern
    Plains into the Ark-La-Tex and Lower Mississippi Valley. Large hail,
    damaging winds and a few tornadoes will be possible. Isolated strong
    wind gusts may also occur in parts of the lower Ohio Valley and
    southern Great Lakes.

    ...Southern Plains/Ark-La-Tex/Lower Mississippi Valley...
    A mid-level shortwave trough will move northeastward into the mid
    Mississippi Valley today, as cyclonic west to southwesterly flow
    remains over much of the south-central U.S. At the surface, an
    outflow boundary will advance southward into the Ark-La-Tex and
    lower Mississippi Valley this morning. Thunderstorms will be ongoing
    along the boundary at the start of the period. These storms will
    move southward across Arkansas, Louisiana and Mississippi. As
    surface temperatures warm during the day, a wind-damage threat is
    expected along the more organized parts of this line. A couple of
    tornadoes will also be possible with rotating elements embedded in
    the line.

    Further west into the southern Plains, an axis of moderate
    instability is forecast to develop by afternoon from east Texas into
    far southern Oklahoma. Additional storms are expected to initiate
    during the mid afternoon along an east-to-west axis of low-level
    convergence in southeast Oklahoma. These storms are expected to move
    southward into northeast Texas and northwestern Louisiana during the
    late afternoon and early evening. Forecast soundings near the Red
    River in far southeast Oklahoma late this afternoon have MLCAPE near
    3500 J/kg, 0-6 km shear in the 30 to 35 knot range, and 700-500 mb
    lapse rates near 8 C/km. This will support supercells with isolated
    large hail. Hailstones of greater than 2 inches in diameter will be
    possible. In addition, 0-3 km storm-relative helicity is forecast to
    reach near 225 m2/s2, which will support a tornado threat with
    supercells. If the storms can transition into a short intense line
    segment, then a localized swath of wind damage may also occur.

    ...Southern Great Lakes/Ohio Valley...
    A mid-level shortwave trough, and an associated cold front will move northeastward into the Great Lakes region today. Ahead of the front,
    a moist airmass will be in place from the Lower Ohio Valley
    northward into lower Michigan. As surface temperatures warm during
    the day, surface dewpoints in the lower 60s F will contribute to
    weak destabilization. This, combined with increasing low-level
    convergence will support thunderstorm development ahead of the
    front. These storms will move eastward across the southern Great
    Lakes and Ohio Valley during the afternoon. Forecast soundings ahead
    of the storms have very steep low-level lapse rates approaching 8
    C/km, which could support an isolated wind-damage threat.

    ..Broyles/Moore.. 04/24/2026

    $$

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  • From COD Weather Processor@1:2320/107 to wx-storm@lists.illinois.edu on Friday, April 24, 2026 12:32:12
    ACUS01 KWNS 241232
    SWODY1
    SPC AC 241230

    Day 1 Convective Outlook
    NWS Storm Prediction Center Norman OK
    0730 AM CDT Fri Apr 24 2026

    Valid 241300Z - 251200Z

    ...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF
    SOUTHEAST OKLAHOMA AND THE ARKLATEX...

    ...SUMMARY...
    Scattered severe thunderstorms are expected today from parts of the
    southern Plains into the ArkLaTex and lower Mississippi Valley.
    Large hail, damaging winds, and a few tornadoes will be possible.
    The greatest threat for supercells with very large hail (2+ inches)
    should focus across parts of southeast Oklahoma into the ArkLaTex.

    ...Southern Plains into the ArkLaTex/Lower Mississippi Valley...
    A band of mainly sub-severe thunderstorms ongoing this morning from
    eastern OK into AR and southern MO is being aided by southwesterly
    warm/moist advection at low levels. With time, this forcing should
    weaken, and a decrease in convective intensity should continue
    through late morning. Outflow from this convection is forecast to
    extend from south-central/southeast OK into AR this afternoon, and
    should serve as a focus for additional robust thunderstorms later
    today. Daytime heating of a moist airmass already present across
    much of the southern Plains into the ArkLaTex and lower MS Valley
    will aid in the development of moderate to strong instability by mid
    afternoon along/south of the residual outflow and east of a surface
    dryline extending from northeast to south-central TX. The greatest
    instability should exist across southeast OK/northeast TX, where
    steep mid-level lapse rates will likely still exist. A weak surface
    low should also be in place across northeast TX by mid to late
    afternoon.

    Large-scale forcing aloft will remain fairly nebulous/weak across
    the southern Plains this afternoon, as a prominent/closed
    upper-level low remains centered over south-central Canada. Still,
    multiple robust thunderstorms should develop by 19-22Z across
    southeast OK along/near the residual outflow boundary as MLCIN
    becomes minimal with robust diurnal heating, and as westerly
    mid/upper-level flow modestly strengthens across the ArkLaTex
    through early evening. This convection will become organized and
    likely supercellular given the presence of around 30-40 kt of
    deep-layer shear. Large to very large hail (potentially up to
    1.5-2.5 inches in diameter) should be the main threat with these
    cells initially. Lower confidence in convective initiation exists
    with southwestward extent along the dryline in TX, but at least a conditional/low threat for severe hail remains apparent.

    With time, some clustering may occur with an increased damaging wind
    threat as convection spreads east-southeastward across the ArkLaTex
    through the evening. One or more clusters may also redevelop along
    the outflow from ongoing convection across the lower MS Valley this
    afternoon, with a threat for mainly scattered damaging winds.
    Low-level flow is not forecast to be overly strong (15-25 kt at 850
    mb), but ample instability and the presence of locally backed
    near-surface winds near the outflow boundary may support enough 0-1
    km SRH for a few tornadoes, especially across southeast OK into the
    ArkLaTex with any persistent supercells. An Enhanced Risk has been
    introduced across this region given increased confidence in multiple
    supercells with significant severe hail potential developing through
    the afternoon/evening.

    ...Great Lakes/Ohio Valley...
    A weak mid-level shortwave trough will move northeastward across the
    Midwest and Upper Great Lakes today. Convection ahead of a cold
    front has generally weakened this morning across the mid MS Valley.
    Modest low-level moisture is forecast to continue advancing
    northward through the day ahead of the front, supporting weak
    instability with filtered daytime heating. Loosely organized
    clusters/cells that develop this afternoon may pose an isolated
    threat for damaging winds as they move northeastward this
    afternoon/evening.

    ..Gleason/Thompson.. 04/24/2026

    $$

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  • From COD Weather Processor@1:2320/107 to wx-storm@lists.illinois.edu on Friday, April 24, 2026 16:32:43
    ACUS01 KWNS 241632
    SWODY1
    SPC AC 241630

    Day 1 Convective Outlook
    NWS Storm Prediction Center Norman OK
    1130 AM CDT Fri Apr 24 2026

    Valid 241630Z - 251200Z

    ...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS ACROSS
    SOUTHEAST OKLAHOMA AND ARKLATEX...

    ...SUMMARY...
    Scattered severe thunderstorms are expected today from parts of the
    southern Plains into the ArkLaTex and lower Mississippi Valley.
    Large hail, damaging winds, and a few tornadoes will be possible.
    The greatest threat for supercells with very large hail (2+ inches)
    should focus across parts of southeast Oklahoma to the ArkLaTex
    region.

    ...Oklahoma/North Texas to ArkLaTex/Lower Mississippi Valley...
    A persistent band of non-severe thunderstorms this morning, and its
    related outflow, continue to settle southward across southeast
    Oklahoma, south-central/southeast Arkansas into northwest
    Mississippi. The southeastern-most portion of the convective line
    may re-intensify across the ArkLaMiss today as the boundary layer
    warms, with some potential for a secondary round of upscale-growing
    storms into tonight across generally the same ArkLaMiss/Lower
    Mississippi Valley region. This includes damaging winds and some
    tornado potential, primarily QLCS-related, especially into this
    evening/tonight via a somewhat stronger wind field.

    The western periphery of the ongoing complex and its outflow should
    continue to decelerate, stall, and modify through the afternoon,
    setting the stage for a semi-corridor of heightened severe potential
    via this modifying outflow in conjunction with the surface triple
    point to this west, with intensifying storm development anticipated
    toward the 4pm-6pm/21z-23z time frame across southeast Oklahoma and
    nearby ArkLaTex. This will be in the presence of ample buoyancy and
    steep mid-level lapse rates. Wind profiles will further support
    intense supercells capable of large to very large hail, along with a
    tornado risk, accentuated by backed low-level winds near the outflow
    boundary and east of the triple point. With time, some clustering
    may occur with an increased damaging wind threat as convection
    spreads east-southeastward.

    Additionally, locally intense storms may also focus farther west
    across southern Oklahoma/Red River vicinity along/north of the southward-sagging front where relatively rich low-level moisture
    will persist in the presence of strong deep-layer shear.

    ...Texas Dryline - North/Central TX to Hill Country/Rio Grande...
    A highly conditional scenario exists in vicinity of the south/southwestward-extending dryline late this afternoon/early
    evening, with a concerning (mostly hail) severe potential should
    storms develop. Short-term guidance varies on the aggressiveness of eastward-mixing/dryline through peak heating, although the 12z Fort
    Worth sounding sampled respectable warm-sector moisture content this
    morning (upper quartile climo; 14.4 g/kg mean mixing ratio).
    Regardless, a concerning high degree of instability (3000+ J/kg
    MLCAPE) will exist near/east of the dryline late this afternoon.

    Short-term models remain rather sparse on explicit indications of
    near-dryline convective initiation. However, sufficient dry line
    convergence and post-dryline heating/mixing could plausibly lead to
    isolated but intense thunderstorm development in the presence of
    negligible capping/boundary-layer inhibition. And while mid-level
    capping will be more prevalent, especially with southward extent,
    upstream 12z soundings from Midland/El Paso (both around -14C 500mb)
    suggest that some additional mid-level cooling is probable. Notably
    stronger mid/high-level winds were also observed in these RAOBs with
    50+ kt winds and 100+ kt winds at 500mb/250mb, respectively.

    Several sub-regional zones of potential isolated deep convective
    development are at least plausible, including in closer proximity to
    the surface triple point across North Texas/Metroplex general
    vicinity, extending into parts of central Texas where low-level
    mixing may be less impactful, and lastly in the immediate vicinity
    of the Rio Grande, potentially influenced by possible storm
    development across the border. If/where storms do develop late this afternoon/early evening, very large hail could occur along with
    localized severe-caliber wind gusts.

    ...Great Lakes/Ohio Valley...
    A weak/convectively influenced mid-level shortwave trough will move northeastward across the Midwest and Upper Great Lakes today.
    Convection ahead of a cold front has generally weakened this morning
    across the mid Mississippi Valley, but multi-layer cloud cover
    remains prevalent. Modest-caliber low-level moisture will continue
    to advect north-northeastward through the day ahead of the front,
    supporting weak instability with filtered daytime heating. Loosely
    organized clusters/cells that develop/intensify this afternoon may
    pose an isolated threat for damaging winds as they move
    northeastward this afternoon and evening. The residual clouds and a
    weakening low-level wind field should curb the overall magnitude of
    the severe risk, hence maintenance of MRGL/Category 1 risk.

    ...Western Nebraska...
    A couple of stronger storms may develop late this afternoon/early
    evening near a southeastward-moving front, further influenced by a
    mid-level impulse embedded within the base of the large-scale trough
    centered over the Canadian Prairies. In the presence of a strong
    deep-layer wind field, modest-caliber CAPE atop a well-mixed
    boundary layer could potentially yield an isolated severe gust/hail.

    ..Guyer/Weinman.. 04/24/2026

    $$

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  • From COD Weather Processor@1:2320/107 to wx-storm@lists.illinois.edu on Friday, April 24, 2026 19:58:46
    ACUS01 KWNS 241958
    SWODY1
    SPC AC 241956

    Day 1 Convective Outlook
    NWS Storm Prediction Center Norman OK
    0256 PM CDT Fri Apr 24 2026

    Valid 242000Z - 251200Z

    ...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS FOR SOUTHEAST
    OKLAHOMA INTO THE ARKLATEX...

    ...SUMMARY...
    Scattered severe thunderstorms are expected today from parts of the
    southern Plains into the ArkLaTex and lower Mississippi Valley.
    Large hail, damaging winds, and a few tornadoes will be possible.
    The greatest threat for supercells with very large hail (2+ inches)
    should focus across parts of southeast Oklahoma to the ArkLaTex
    region.

    ...20Z Update...
    Much of the previous forecast (see below) remains on track. The
    primary changes made to the current outlook were to trim severe
    probabilities across portions of the OH Valley/Great Lakes, and the
    Mid-MS Valley, where either the passage of a surface cold front, or
    robust convection, has promoted boundary layer stabilization. More
    minor changes involved small adjustments to current severe and
    thunder probabilities ahead of storms to account for observations
    and the latest guidance consensus.

    ..Squitieri.. 04/24/2026

    .PREV DISCUSSION... /ISSUED 1130 AM CDT Fri Apr 24 2026/

    ...Oklahoma/North Texas to ArkLaTex/Lower Mississippi Valley...
    A persistent band of non-severe thunderstorms this morning, and its
    related outflow, continue to settle southward across southeast
    Oklahoma, south-central/southeast Arkansas into northwest
    Mississippi. The southeastern-most portion of the convective line
    may re-intensify across the ArkLaMiss today as the boundary layer
    warms, with some potential for a secondary round of upscale-growing
    storms into tonight across generally the same ArkLaMiss/Lower
    Mississippi Valley region. This includes damaging winds and some
    tornado potential, primarily QLCS-related, especially into this
    evening/tonight via a somewhat stronger wind field.

    The western periphery of the ongoing complex and its outflow should
    continue to decelerate, stall, and modify through the afternoon,
    setting the stage for a semi-corridor of heightened severe potential
    via this modifying outflow in conjunction with the surface triple
    point to this west, with intensifying storm development anticipated
    toward the 4pm-6pm/21z-23z time frame across southeast Oklahoma and
    nearby ArkLaTex. This will be in the presence of ample buoyancy and
    steep mid-level lapse rates. Wind profiles will further support
    intense supercells capable of large to very large hail, along with a
    tornado risk, accentuated by backed low-level winds near the outflow
    boundary and east of the triple point. With time, some clustering
    may occur with an increased damaging wind threat as convection
    spreads east-southeastward.

    Additionally, locally intense storms may also focus farther west
    across southern Oklahoma/Red River vicinity along/north of the southward-sagging front where relatively rich low-level moisture
    will persist in the presence of strong deep-layer shear.

    ...Texas Dryline - North/Central TX to Hill Country/Rio Grande...
    A highly conditional scenario exists in vicinity of the south/southwestward-extending dryline late this afternoon/early
    evening, with a concerning (mostly hail) severe potential should
    storms develop. Short-term guidance varies on the aggressiveness of eastward-mixing/dryline through peak heating, although the 12z Fort
    Worth sounding sampled respectable warm-sector moisture content this
    morning (upper quartile climo; 14.4 g/kg mean mixing ratio).
    Regardless, a concerning high degree of instability (3000+ J/kg
    MLCAPE) will exist near/east of the dryline late this afternoon.

    Short-term models remain rather sparse on explicit indications of
    near-dryline convective initiation. However, sufficient dry line
    convergence and post-dryline heating/mixing could plausibly lead to
    isolated but intense thunderstorm development in the presence of
    negligible capping/boundary-layer inhibition. And while mid-level
    capping will be more prevalent, especially with southward extent,
    upstream 12z soundings from Midland/El Paso (both around -14C 500mb)
    suggest that some additional mid-level cooling is probable. Notably
    stronger mid/high-level winds were also observed in these RAOBs with
    50+ kt winds and 100+ kt winds at 500mb/250mb, respectively.

    Several sub-regional zones of potential isolated deep convective
    development are at least plausible, including in closer proximity to
    the surface triple point across North Texas/Metroplex general
    vicinity, extending into parts of central Texas where low-level
    mixing may be less impactful, and lastly in the immediate vicinity
    of the Rio Grande, potentially influenced by possible storm
    development across the border. If/where storms do develop late this afternoon/early evening, very large hail could occur along with
    localized severe-caliber wind gusts.

    ...Great Lakes/Ohio Valley...
    A weak/convectively influenced mid-level shortwave trough will move northeastward across the Midwest and Upper Great Lakes today.
    Convection ahead of a cold front has generally weakened this morning
    across the mid Mississippi Valley, but multi-layer cloud cover
    remains prevalent. Modest-caliber low-level moisture will continue
    to advect north-northeastward through the day ahead of the front,
    supporting weak instability with filtered daytime heating. Loosely
    organized clusters/cells that develop/intensify this afternoon may
    pose an isolated threat for damaging winds as they move
    northeastward this afternoon and evening. The residual clouds and a
    weakening low-level wind field should curb the overall magnitude of
    the severe risk, hence maintenance of MRGL/Category 1 risk.

    ...Western Nebraska...
    A couple of stronger storms may develop late this afternoon/early
    evening near a southeastward-moving front, further influenced by a
    mid-level impulse embedded within the base of the large-scale trough
    centered over the Canadian Prairies. In the presence of a strong
    deep-layer wind field, modest-caliber CAPE atop a well-mixed
    boundary layer could potentially yield an isolated severe gust/hail.

    $$

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  • From COD Weather Processor@1:2320/107 to wx-storm@lists.illinois.edu on Saturday, April 25, 2026 01:02:46
    ACUS01 KWNS 250102
    SWODY1
    SPC AC 250100

    Day 1 Convective Outlook
    NWS Storm Prediction Center Norman OK
    0800 PM CDT Fri Apr 24 2026

    Valid 250100Z - 251200Z

    ...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF
    THE ARK-LA-TEX...

    ...SUMMARY...
    A severe threat will continue this evening from the southern Plains,
    into the Ark-La-Tex and Lower Mississippi Valley. Large hail, wind
    damage and a couple tornadoes will be possible. The strongest of
    storms could produce hailstones greater than 2 inches in diameter.

    ...Southern Plains/Ark-La-Tex/Lower Mississippi Valley...
    A mid-level shortwave trough is evident on water vapor over the
    Ark-La-Tex this evening. Ahead of the trough, a cluster of strong to
    severe thunderstorms is ongoing from near the Red River
    northeastward across far southeast Oklahoma into western Arkansas.
    This cluster is located at the northern end of an axis of strong
    instability, with the RAP showing MLCAPE near the instability axis
    in the 2500 to 3500 J/kg range. In this area, RAP forecast soundings
    also show steep mid-level lapse rates, exceeding 7.5 C/km. In
    addition to this favorable thermodynamic environment, a low to
    mid-level speed max is evident over the Ark-La-Tex, where flow is
    westerly at 45 to 50 knots. This is creating moderate to strong
    deep-layer shear, which will continue to be favorable for severe
    storms this evening. Cells that can remain semi-descrete will could
    be supercellar and have potential for large to very large hail.
    Hailstones greater than 2 inches in diameter will be possible with
    the more intense storms. The large hail threat should persist for a
    few more hours as the cluster interacts with the strong instability
    over the Ark-La-Tex. Supercells could also be associated with a
    wind-damage and tornado threat.

    The cluster of storms is expected to gradually organize into a
    linear MCS, moving east-southeastward into the lower Mississippi
    Valley during the mid to late evening. Severe wind gusts will become
    the primary threat as the line segment develops. A couple of QLCS
    tornadoes will be possible as well. The severe threat may persist
    into the early overnight period...See MCD 521 and 523.

    ..Broyles.. 04/25/2026

    $$

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  • From COD Weather Processor@1:2320/107 to wx-storm@lists.illinois.edu on Saturday, April 25, 2026 06:02:21
    ACUS01 KWNS 250602
    SWODY1
    SPC AC 250600

    Day 1 Convective Outlook
    NWS Storm Prediction Center Norman OK
    0100 AM CDT Sat Apr 25 2026

    Valid 251200Z - 261200Z

    ...THERE IS A MODERATE RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF
    CENTRAL AND SOUTHEAST OKLAHOMA...

    ...SUMMARY...
    Severe thunderstorms with large to very large hail, tornadoes and
    wind damage will be likely today across parts of the southern Plains
    and Arklatex. Hailstones greater than 3 inches in diameter and
    strong tornadoes will be possible.

    ...Southern Plains/Ark-La-Tex...
    A mid-level shortwave trough will move eastward across the southern
    Rockies this morning and into the southern Plains this afternoon. At
    the surface, a low will deepen across northwest Texas. Ahead of the
    approaching trough, moisture advection will take place in the
    southern Plains, as surface dewpoints over Oklahoma increase into
    the mid to upper 60s F. This will contribute to strong
    destabilization by afternoon from parts of north Texas into
    Oklahoma. An outflow boundary over north Texas will move northward
    this afternoon into southern Oklahoma. Low-level convergence will
    increase along this boundary in the afternoon. Low-level convergence
    will also increase along a front moving into central Oklahoma. These
    two zones will be the focus for convective initiation this
    afternoon. Severe storms are expected to develop and move
    southeastward across much of Oklahoma and north Texas this afternoon
    and evening.

    RAP forecast soundings late this afternoon in far southern Oklahoma
    to the north of the Dallas/Fort Worth Metroplex increase MLCAPE into
    the 3000 to 4000 J/kg range and have 700-500 mb lapse rates near 8
    C/km range. This combined with long hodographs and a tendency for
    the storms to remain discrete will be very favorable for supercells
    with large hail. Hailstones greater than 3 inches in diameter will
    be possible with the more intense cores. In addition, a 25 to 30
    knot low-level jet will be in place late this afternoon from north
    Texas into east-central Oklahoma. This feature will create strong
    low-level shear profiles favorable for tornadoes. Low-level shear
    will be amplified by the boundary in southern Oklahoma. By early
    this evening, forecast sounding near the western edge of the
    low-level jet have 0-3 km storm-relative helicity in the 300 to 400
    m2/s2 range. This will support a potential for strong tornadoes with
    the more robust supercells. Also, a wind-damage threat will develop
    with supercells. The wind-damage threat will continue through much
    of the evening as a cluster of severe storms moves southeastward
    toward the Ark-La-Tex.

    ...Central Plains...
    A mid-level shortwave trough will move into the southern and central
    Plains today. At the surface, a cold front will advance southward
    through western and central Kansas into western Oklahoma. To the
    east of the front, a well-defined moist axis will be located from
    central Oklahoma into east-central Kansas. Along the western edge of
    the moist airmass, a north-to-south corridor of low-level
    convergence is forecast which will focus convective initiation. As
    instability maximizes this afternoon, thunderstorms are expected to
    develop and move southeastward across much of central and southern
    Kansas into northern Oklahoma. Forecast soundings across this area
    by late afternoon show moderate instability and 0-6 km shear in the
    30 to 40 knot range, which will support a large hail and wind-damage
    threat.

    ...Central and Southwest Texas...
    A moist airmass will remain over much of the southern Plains today.
    Along the northwestern edge of the moist sector, low-level
    convergence will increase along a well-developed dryline. Although
    large-scale ascent will remain minimal, isolated storms could
    develop late this afternoon to the east of the dryline. Moderate
    deep-layer shear and steep mid-level lapse rates will support an
    isolated threat for large hail and severe wind gusts.

    ..Broyles/Moore.. 04/25/2026

    $$

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  • From COD Weather Processor@1:2320/107 to wx-storm@lists.illinois.edu on Saturday, April 25, 2026 12:52:17
    ACUS01 KWNS 251252
    SWODY1
    SPC AC 251250

    Day 1 Convective Outlook
    NWS Storm Prediction Center Norman OK
    0750 AM CDT Sat Apr 25 2026

    Valid 251300Z - 261200Z

    ...THERE IS A MODERATE RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF CENTRAL/EASTERN OKLAHOMA AND FAR NORTH TEXAS...

    ...SUMMARY...
    Severe thunderstorms with very large to giant hail (2 to 4+ inches
    in diameter), tornadoes, and scattered damaging winds are expected
    late this afternoon through tonight across parts of the southern
    Plains and ArkLaTex. A couple of strong tornadoes are possible.

    ...Synopsis...
    A closed mid/upper-level low will remain centered over Manitoba and Saskatchewan today, while generally zonal/westerly mid-level winds
    persist over the southern Plains. A weak shortwave trough over the Southwest/southern Rockies this morning is forecast to eject
    eastward over the southern/central Plains by late this afternoon. At
    the surface, a convectively reinforced outflow boundary draped
    across north-central/northeast TX will shift northward into OK as a
    warm front today, while a low gradually deepens over northwest TX by
    late afternoon/early evening. Rich low-level moisture characterized
    by upper 60s to low 70s surface dewpoints will likely advance as far
    north as central into southeast OK through peak diurnal heating,
    with lesser moisture return farther north into northwest OK, KS, and
    southeast NE ahead of a cold front. A dryline will extend
    south-southwestward from the surface low across central into
    south-central TX.

    ...Southern/Central Plains into the ArkLaTex...
    Strong to locally extreme instability (MLCAPE 2500-4000+ J/kg) is
    expected to develop along/east of the dryline in TX and south of the
    warm front in OK by peak afternoon heating. The presence of
    seasonably cool temperatures aloft and 7.5-8.5 C/km mid-level lapse
    rates will also support this very favorable thermodynamic
    environment. While large-scale ascent associated with the ejecting
    mid-level shortwave trough is not expected to be overly robust, it
    should be sufficient for at least isolated thunderstorm initiation
    by mid afternoon to early evening (around 20-23Z), especially near
    the warm front/dryline intersection in south-central OK.

    40-50 kt of generally westerly effective bulk shear will support
    intense supercells, with multiple right/left splits likely. This
    activity will quickly intensify shortly after convective initiation,
    and very large to giant hail appears likely (2-4+ inches in
    diameter). The Enhanced/Moderate Risk areas have been expanded
    slightly in OK and north TX to account for deviant thunderstorm
    motions and the potential for multiple intense supercells to track east-southeastward along/near the warm front. A conditional risk for
    supercells remains apparent farther south along the length of the
    dryline in TX, although confidence in convective initiation remains
    low. Have maintained the Marginal Risk for this potential, with some
    expansion eastward in case isolated thunderstorms do initiate.

    Modest southerly low-level winds (around 20-30 kt at 850 mb) will be
    present through this evening across the southern Plains. Locally
    enhanced 0-1 km SRH will be present near the warm front with backed near-surface winds. This will support a threat for tornadoes with
    any right-split supercells that can remain surface based. A slight
    increase in the low-level jet this evening and presence of very
    strong to locally extreme buoyancy also suggests some threat for a
    couple of EF-2+ tornadoes. With time this evening, convection may
    grow upscale and pose a threat for scattered severe/damaging winds
    as it spreads southeastward into the ArkLaTex.

    Farther north in KS/NE, instability and low-level moisture is
    expected to remain weaker/more limited. But, some supercells/small
    clusters may eventually develop this afternoon and move
    east-northeastward given sufficient deep-layer shear for updraft
    organization. Isolated to scattered severe hail and damaging winds
    should be the main threat with this activity through mid evening
    before it eventually weakens.

    ...Lower Mississippi Valley/Central Gulf Coast...
    A long-lived convective cluster has nearly moved offshore from the
    coast of AL/MS/LA. In its wake, a rain-cooled airmass exists across
    much of the lower MS Valley. This should hinder the development of
    much surface-based instability through early afternoon. Still,
    eventual re-destabilization should occur along/near the remnant
    outflow boundary. Isolated cells that may develop could pose some
    risk for hail and damaging winds.

    ..Gleason/Thompson.. 04/25/2026

    $$

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  • From COD Weather Processor@1:2320/107 to wx-storm@lists.illinois.edu on Saturday, April 25, 2026 16:33:21
    ACUS01 KWNS 251633
    SWODY1
    SPC AC 251631

    Day 1 Convective Outlook
    NWS Storm Prediction Center Norman OK
    1131 AM CDT Sat Apr 25 2026

    Valid 251630Z - 261200Z

    ...THERE IS A MODERATE RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF CENTRAL/EASTERN OKLAHOMA AND FAR NORTH TEXAS...

    ...SUMMARY...
    Severe thunderstorms with very large to giant hail (2 to 4+ inches
    in diameter), tornadoes, and scattered damaging winds are expected
    late this afternoon through tonight across parts of the southern
    Plains and ArkLaTex. A couple of strong tornadoes are possible.

    ...Southern Plains and ArkLaTex...
    While stratus remains semi-prevalent this morning along/north of the near-stationary front, strong to locally extreme instability (MLCAPE
    2500-4000+ J/kg) is expected to develop along/east of the dryline in
    Texas and Red River-vicinity triple point, and to the south of slow-northward-shifting warm front in Oklahoma by peak afternoon
    heating. The presence of seasonably cool temperatures aloft and
    7.5-8.5 C/km mid-level lapse rates will also support this very
    unstable thermodynamic environment. While large-scale ascent
    associated with the ejecting mid-level shortwave trough is not
    expected to be overly robust, the arrival of a shortwave
    trough/mid-level speed max will be favorably timed atop the warm
    sector. At least widely scattered thunderstorm initiation is
    expected by mid/late afternoon to early evening (around 20-23Z),
    especially near the warm front/dryline intersection and a bit north
    across south-central/east-central Oklahoma.

    40-50 kt of generally westerly effective bulk shear will support
    intense supercells, with multiple right/left splits expected. This
    activity will quickly intensify shortly after convective initiation,
    and very large to giant hail appears likely (2-4+ inches in
    diameter). The potential exists for multiple intense supercells to
    track east-southeastward along/near the warm front. A conditional
    risk for supercells remains apparent farther south along the length
    of the dryline in TX, although confidence in convective initiation
    remains low, but at least isolated but intense deep convective
    development is plausible, especially in closer proximity to the
    surface triple point across North Texas.

    Modest southerly low-level winds (around 20-30 kt at 850 mb) will be
    present through this evening across the southern Plains. Locally
    enhanced 0-1 km SRH will exist near the warm front with backed
    near-surface winds. This will support a threat for tornadoes with
    any right-split supercells that remain surface based. A slight
    increase in the low-level jet this evening and presence of very
    strong to locally extreme buoyancy also suggests some threat for a
    few EF-2+ tornadoes. With time this evening, convection may
    grow upscale and pose a threat for scattered severe/damaging winds
    as storm clusters move southeastward across the Red River toward and
    across the ArkLaTex.

    ...Central Plains including Kansas/Nebraska...
    Farther north, instability and low-level moisture is expected to
    remain weaker/more limited. But, some supercells/small clusters are
    expected to develop this afternoon and move east-northeastward given
    sufficient deep-layer shear for updraft organization. Isolated to
    scattered severe hail and damaging winds should be the main threat
    with this activity through mid-evening before eventually weakening.

    ...Lower Mississippi Valley/Middle Gulf Coast...
    Strong to locally severe storms may redevelop later today as outflow
    modifies in the wake of the early morning MCS, with the potential
    that additional storms, potentially in the form of another MCS,
    approach the region from the northwest late tonight.

    ..Guyer/Barnes.. 04/25/2026

    $$

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  • From COD Weather Processor@1:2320/107 to wx-storm@lists.illinois.edu on Saturday, April 25, 2026 19:50:52
    ACUS01 KWNS 251950
    SWODY1
    SPC AC 251948

    Day 1 Convective Outlook
    NWS Storm Prediction Center Norman OK
    0248 PM CDT Sat Apr 25 2026

    Valid 252000Z - 261200Z

    ...THERE IS A MODERATE RISK OF SEVERE THUNDERSTORMS FOR PORTIONS OF
    CENTRAL AND SOUTHEASTERN OKLAHOMA INTO FAR NORTHERN TEXAS...

    ...SUMMARY...
    Severe thunderstorms with very large to giant hail (2 to 4+ inches
    in diameter), tornadoes (some EF2+), and scattered damaging winds
    are expected late this afternoon through tonight across parts of the
    southern Plains and ArkLaTex.

    ...20Z Update...
    The previous forecast (see below) remains on track. The main
    adjustments made to the outlook (albeit minor) were to slightly
    extend the moderate risk-driven hail probabilities to the southwest
    to align with the current position of the surface boundary. The
    latest high-resolution guidance consensus has consistently depicted
    some of the most robust storms to form and anchor along this
    boundary. With current mesoanalysis already showing 4000+ J/kg
    MLCAPE colocated across far south-central OK, the current thinking
    is that intense supercells traversing this boundary will produce
    severe hail in the 3-4 inch range, and a couple of stones above 4
    inches in diameter cannot be completely ruled out. Tornadoes may
    also occur, with the best chance of a strong to intense tornado
    being with a boundary-anchoring supercell that can remain discrete
    and dominant.

    ..Squitieri.. 04/25/2026

    .PREV DISCUSSION... /ISSUED 1131 AM CDT Sat Apr 25 2026/

    ...Southern Plains and ArkLaTex...
    While stratus remains semi-prevalent this morning along/north of the near-stationary front, strong to locally extreme instability (MLCAPE
    2500-4000+ J/kg) is expected to develop along/east of the dryline in
    Texas and Red River-vicinity triple point, and to the south of slow-northward-shifting warm front in Oklahoma by peak afternoon
    heating. The presence of seasonably cool temperatures aloft and
    7.5-8.5 C/km mid-level lapse rates will also support this very
    unstable thermodynamic environment. While large-scale ascent
    associated with the ejecting mid-level shortwave trough is not
    expected to be overly robust, the arrival of a shortwave
    trough/mid-level speed max will be favorably timed atop the warm
    sector. At least widely scattered thunderstorm initiation is
    expected by mid/late afternoon to early evening (around 20-23Z),
    especially near the warm front/dryline intersection and a bit north
    across south-central/east-central Oklahoma.

    40-50 kt of generally westerly effective bulk shear will support
    intense supercells, with multiple right/left splits expected. This
    activity will quickly intensify shortly after convective initiation,
    and very large to giant hail appears likely (2-4+ inches in
    diameter). The potential exists for multiple intense supercells to
    track east-southeastward along/near the warm front. A conditional
    risk for supercells remains apparent farther south along the length
    of the dryline in TX, although confidence in convective initiation
    remains low, but at least isolated but intense deep convective
    development is plausible, especially in closer proximity to the
    surface triple point across North Texas.

    Modest southerly low-level winds (around 20-30 kt at 850 mb) will be
    present through this evening across the southern Plains. Locally
    enhanced 0-1 km SRH will exist near the warm front with backed
    near-surface winds. This will support a threat for tornadoes with
    any right-split supercells that remain surface based. A slight
    increase in the low-level jet this evening and presence of very
    strong to locally extreme buoyancy also suggests some threat for a
    few EF-2+ tornadoes. With time this evening, convection may
    grow upscale and pose a threat for scattered severe/damaging winds
    as storm clusters move southeastward across the Red River toward and
    across the ArkLaTex.

    ...Central Plains including Kansas/Nebraska...
    Farther north, instability and low-level moisture is expected to
    remain weaker/more limited. But, some supercells/small clusters are
    expected to develop this afternoon and move east-northeastward given
    sufficient deep-layer shear for updraft organization. Isolated to
    scattered severe hail and damaging winds should be the main threat
    with this activity through mid-evening before eventually weakening.

    ...Lower Mississippi Valley/Middle Gulf Coast...
    Strong to locally severe storms may redevelop later today as outflow
    modifies in the wake of the early morning MCS, with the potential
    that additional storms, potentially in the form of another MCS,
    approach the region from the northwest late tonight.

    $$

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  • From COD Weather Processor@1:2320/107 to wx-storm@lists.illinois.edu on Sunday, April 26, 2026 01:01:54
    ACUS01 KWNS 260101
    SWODY1
    SPC AC 260100

    Day 1 Convective Outlook
    NWS Storm Prediction Center Norman OK
    0800 PM CDT Sat Apr 25 2026

    Valid 260100Z - 261200Z

    ...THERE IS A MODERATE RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF
    SOUTHEAST OKLAHOMA AND FAR NORTHEAST TEXAS...

    ...SUMMARY...
    Severe thunderstorms with a potential for large to very large,
    tornadoes and severe wind gust will continue this evening into
    tonight across parts of the southern Plains and Ark-La-Tex.
    Additional severe storms with hail and isolated severe gusts will be
    possible in parts of the central Plains.

    ...Southern Plains/Ark-La-Tex...
    A low-amplitude mid-level shortwave trough is evident on water vapor
    imagery from east-central Kansas southward into west-central
    Oklahoma. At the surface, a moist airmass is located over the
    eastern part of the southern Plains into the Ark-La-Tex, where
    surface dewpoints are in the mid 60s to the mid 70s F. The RAP shows
    strong instability across north Texas and southern Oklahoma, with
    MLCAPE in the 3000 to 4000 J/kg range. Scattered severe storms are
    ongoing near an instability maximum that is near the Red River north
    of the Dallas/Fort Worth Metroplex. The RAP is also showing very
    steep mid-level lapse rates over southern Oklahoma and far north
    Texas. 700-500 mb lapse rates are estimated to be in the 7.5 to 8
    C/km range. This will be favorable for large to very large hail.
    Hailstones of 2 to 3 inches in diameter will be possible with the
    more intense supercells.

    In addition, a low-level jet is analyzed from northeast Texas into
    eastern Oklahoma. The low-level jet has not strengthened as much as
    was originally forecast, but is still expected to gradually ramp up
    over the next few hours. This will increase low-level shear
    maintaining a tornado threat. The RAP still increases 0-3 km
    storm-relative helicity into the 350 to 400 m2/s2 range within a
    couple of hours, suggesting that a potential for strong tornadoes
    will continue. A wind-damage threat is also expected to be
    maintained this evening into the early overnight period, as a severe
    convective cluster moves southeastward toward the Ark-La-Tex.

    Concerning the placement of the Moderate, it appears that severe
    threat coverage will be more limited north of I-40. For this reason,
    the northern extent of the Moderate Risk area has been trimmed.

    ...Central Plains...
    Water vapor currently shows a subtle shortwave trough moving into
    the mid Missouri Valley and another one moving into the central High
    Plains. At the surface, a moist airmass is located from central and
    eastern Kansas into far southeast Nebraska, where scattered
    thunderstorms are ongoing. Across this area at mid-levels, flow is
    generally from west to southwest at 30 to 40 knots. This is creating
    sufficient deep-layer shear for organized severe storms. Steep
    mid-level lapse rates will be favorable for isolated large hail.
    Severe wind gusts will also be possible.

    ..Broyles.. 04/26/2026

    $$

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  • From COD Weather Processor@1:2320/107 to wx-storm@lists.illinois.edu on Sunday, April 26, 2026 05:33:56
    ACUS01 KWNS 260533
    SWODY1
    SPC AC 260532

    Day 1 Convective Outlook
    NWS Storm Prediction Center Norman OK
    1232 AM CDT Sun Apr 26 2026

    Valid 261200Z - 271200Z

    ...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF
    THE CENTRAL PLAINS...

    ...SUMMARY...
    Scattered severe storms with large to very hail, damaging wind gusts
    and tornadoes are expected this afternoon and evening across parts
    of the central and southern Plains. Strong tornadoes and hailstones
    greater than 2 inches in diameter will be possible. Hail and
    isolated severe gusts will also be possible in parts of the
    Ark-La-Tex and lower Mississippi Valley.

    ...Southern and Central Plains...
    A vigorous mid-level trough will eject northeastward toward the
    southern and central Rockies this afternoon into tonight, as an
    associated mid-level jet translates east-northeastward through the
    Desert Southwest. The exit region of the mid-level jet will
    overspread the central Plains by this evening providing lift and
    strong deep-layer shear, favorable for severe storms. At the
    surface, a lee trough will deepen over the southern and central High
    Plains, as moisture advects northward from Oklahoma into Kansas.
    Throughout most of the day, large-scale ascent will be limited over
    the moist sector. Isolated thunderstorms with hail and severe gusts
    will be possible in areas with maximized low-level convergence and
    strong instability. Convective coverage will likely increase during
    the evening as the mid-level jet max approaches, and as a 40 to 50
    knot low-level jet strengthens. By mid to late evening and into the
    overnight period, scattered severe storms will be likely in parts of
    the central Plains and Ozarks, with isolated storms possible in the
    southern Plains.

    Model forecasts suggest that a pocket of strong instability will be
    in place over Oklahoma early this evening, but that a capping
    inversion will exist over much of the moist sector. RAP forecast
    soundings at Salina, Kansas gradually erode the capping inversion
    during the evening as low-level moisture increases. By late evening
    in central Kansas, MUCAPE is forecast to be in the 4500 to 5000 J/kg
    range with 0-6 km shear near 50 knots. 700-500 mb lapse rates are
    forecast to be very steep and could exceed 8 C/km. This should be
    favorable for supercells with large to very large hail. Hailstones
    greater than 2 inches in diameter will be possible. Although the
    storms will likely be elevated during much of the evening, some
    cells could become surface-based in the mid to late evening or early
    overnight period. Once this occurs, a tornado threat should develop.
    The more intense supercells could produce a strong tornado or two. A wind-damage threat will also be possible.

    Further south into parts of Oklahoma, limited large-scale ascent
    will make initiation difficult along the dryline. If a storm can
    become established during the late afternoon or early to mid
    evening, extreme instability (MLCAPE near 5000 J/kg) and steep
    mid-level lapse rates near 8 C/Km will be very favorable for large
    to very large hail. 0-3 km storm-relative helicity around 250 m2/s2
    would also support a tornado threat.

    ...Ark-La-Tex/Lower Mississippi Valley...
    The eastern edge of a moist and unstable airmass will be located in
    the lower Mississippi Valley today. Although large-scale ascent will
    be weak due to the presence of a mid-level ridge, isolated
    convective initiation will be possible in areas that locally heat up
    the most. Cells that can strengthen in the late afternoon and early
    evening could produce isolated severe gusts and hail.

    ...Central and Southwest Texas...
    The western edge of an extremely unstable airmass will be located
    from central Texas into southwest Texas this afternoon. Isolated
    thunderstorm initiation will be possible just to the east of a
    dryline, as low-level convergence increases late this afternoon. The
    extreme instability (MLCAPE of 4000 to 5000 J/kg) with moderate
    deep-layer shear and steep mid-level lapse rates would be favorable
    for isolated large hail and strong wind gusts.

    ..Broyles/Moore.. 04/26/2026

    $$

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  • From COD Weather Processor@1:2320/107 to wx-storm@lists.illinois.edu on Sunday, April 26, 2026 12:57:59
    ACUS01 KWNS 261257
    SWODY1
    SPC AC 261256

    Day 1 Convective Outlook
    NWS Storm Prediction Center Norman OK
    0756 AM CDT Sun Apr 26 2026

    Valid 261300Z - 271200Z

    ...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF
    THE SOUTHERN/CENTRAL PLAINS...

    ...SUMMARY...
    Scattered severe thunderstorms with large to very hail, damaging
    winds and tornadoes are expected this afternoon through tonight
    across parts of the southern/central Plains. A couple of strong
    tornadoes and hailstones up to 2-3 inches in diameter are possible.

    ...Southern/Central Plains to the Mid Mississippi Valley...
    Fairly substantial changes have been made to the outlook based on
    latest observational and guidance trends. Namely, the Enhanced Risk
    has been expanded into northern OK to account for the potential of
    both surface-based supercells this afternoon, and elevated
    supercells this evening/tonight. The Slight Risk has been expanded
    southward into north-central TX for a somewhat more
    conditional/uncertain supercell threat. The eastern extent of severe probabilities have also been expanded in MO to account for a
    potential cluster producing severe/damaging winds occurring late
    tonight into early Monday morning.

    A weak lead mid-level vorticity maximum over the central High Plains
    this morning should continue to aid elevated thunderstorm
    development across KS through the afternoon. Increasing MUCAPE with
    persistent low-level warm/moist advection and steepening mid-level
    lapse rates combined with strong deep-layer shear will support
    organized updrafts, including the potential for supercells. This
    convection will probably tend to remain elevated to the north of a
    front as it spreads east-northeastward over the central Plains, but
    scattered large hail may occur given the overall favorable
    environment. Isolated 2+ inch diameter hail also appears possible
    with the strongest cores. Eventually, this activity may pose a
    greater threat for damaging winds across eastern KS into western MO
    by late afternoon/early evening, if it can become truly surface
    based.

    A more notable mid-level shortwave trough is expected to eject
    northeastward across the Southwest and southern/central High Plans
    today, accompanied by a 50-60 kt southwesterly mid-level jet. Weak
    lee cyclogenesis is forecast to occur across the southeast
    CO/northeast NM vicinity in response, with the surface low
    developing into the OK Panhandle and southwest KS by this evening.
    Strong to locally extreme instability is once again forecast to
    develop to the east of a sharpening dryline across western/central
    OK as daytime heating of a moist airmass occurs. There is still a
    fair amount of uncertainty with the placement of an effective warm
    front by late afternoon/early evening, but current expectations are
    for this boundary to be draped somewhere near north-central OK by
    peak afternoon heating. The surface triple point may serve as a
    focus for convective initiation today, although better large-scale
    ascent associated with the mid-level shortwave trough overspreading
    the warm sector will be delayed until this evening and past peak
    diurnal heating.

    Greater than average uncertainty exists regarding the potential for surface-based convective initiation today in OK/north TX. Still, it
    appears possible that multiple supercells may develop with gradual
    erosion of lingering MLCIN and weak ascent preceding the ejecting
    shortwave trough. Any supercells that can root and ingest the ample
    low-level moisture will be capable of producing very large hail
    (2-3+ inches in diameter) given a overall rather favorable
    environment. The tornado potential is less clear through the day,
    but a southerly low-level jet will quickly strengthen this evening
    and aid curved/elongated hodographs with strong effective SRH. A
    somewhat conditional/uncertain threat for a couple of strong
    tornadoes remains apparent, especially if any supercells that can
    form this afternoon persist into the evening.

    Additional, somewhat elevated supercells may form this evening into
    tonight along/north of the warm front from northwest OK near the
    triple point into KS. This activity will also pose a threat for
    large to very large hail. Some guidance suggests a cluster
    eventually evolves from this convection across eastern KS into MO
    late tonight/early Monday morning. If this occurs, then a greater
    threat for severe/damaging winds would exist.

    Farther south into TX, the forcing for ascent will remain
    weak/nebulous along the dryline. Still, some potential for a few
    supercells is apparent across north-central TX where the greatest
    heating and minimal MLCIN is forecast to exist. Large to very large
    hail should be the main threat with any splitting supercells that
    can develop this afternoon along/east of the dryline and be
    sustained.

    ...ArkLaTex/Lower Mississippi Valley/Central Gulf Coast...
    A small cluster will continue tracking southeastward this morning
    from southern MS to the central Gulf Coast. With sufficient
    low-level moisture and instability in place ahead of this
    convection, isolated damaging winds may occur. A pair of supercells
    across northeast TX have fluctuated in intensity over the past
    couple of hours. The potential for additional thunderstorms to form
    on the western flank/outflow of this morning convection remains
    unclear given weak large-scale forcing and the low-level jet
    forecast to weaken further through the morning. If any additional
    convection can form, it would pose an isolated severe hail and
    damaging wind threat.

    ..Gleason/Thompson.. 04/26/2026

    $$

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  • From COD Weather Processor@1:2320/107 to wx-storm@lists.illinois.edu on Sunday, April 26, 2026 16:56:03
    ACUS01 KWNS 261655
    SWODY1
    SPC AC 261654

    Day 1 Convective Outlook
    NWS Storm Prediction Center Norman OK
    1154 AM CDT Sun Apr 26 2026

    Valid 261630Z - 271200Z

    ...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS ACROSS KANSAS
    AND NORTHERN OKLAHOMA TO WESTERN MISSOURI...

    ...SUMMARY...
    Scattered severe thunderstorms with large to very large hail,
    damaging winds and tornadoes are expected this afternoon through
    tonight across parts of the southern/central Plains to Lower
    Missouri Valley. A couple of strong tornadoes and hailstones up to
    2-3 inches in diameter are possible.

    ...Southern/Central Plains to the Mid Mississippi Valley...
    Appreciable severe potential is still readily apparent especially
    later this afternoon into tonight, although sub-regional details
    remain quite complex, particularly regarding the southern extent of
    deep convective initiation southward along the dryline.

    A weak lead mid-level vorticity maximum over the central High Plains
    early today will continue to aid elevated thunderstorm development
    across Kansas through the afternoon. See Mesoscale Discussion 547
    for short-term details. Increasing MUCAPE with persistent low-level
    warm/moist advection and steepening mid-level
    lapse rates combined with strong deep-layer shear will support
    organized updrafts, including the potential for supercells. This
    convection will probably tend to remain elevated to the north of a
    front as it spreads east-northeastward over the central Plains, but
    scattered large hail may occur given the overall favorable
    environment. Isolated 2+ inch diameter hail also appears possible
    with the strongest cores. Eventually, this activity may pose a
    greater threat for damaging winds across eastern Kansas into western
    Missouri by late afternoon/early evening.

    A more notable mid-level shortwave trough is expected to eject
    northeastward across the Southwest and southern/central High Plans
    today, accompanied by a 50-60 kt southwesterly mid-level jet. Weak
    lee cyclogenesis is forecast to occur across the southeast
    Colorado/northeast New Mexico vicinity in response, with the surface
    low developing into the Oklahoma Panhandle and southwest Kansas by
    this evening. Strong to locally extreme instability is forecast to
    develop east of a sharpening dryline across western/central Oklahoma
    as daytime heating of a moist airmass occurs. There is still a fair
    amount of uncertainty with the placement of an effective warm front
    by late afternoon/early evening, but current expectations are for
    this boundary to be draped somewhere near north-central Oklahoma by
    peak afternoon heating. The surface triple point may serve as a
    focus for convective initiation later today into this evening,
    although better large-scale ascent associated with the mid-level
    shortwave trough overspreading the warm sector will be delayed until
    this evening and past peak diurnal heating.

    Greater than average uncertainty exists regarding the potential for surface-based convective initiation today in Oklahoma/north Texas,
    but the volatile environment and ample conditional-type potential is concerning. It appears possible that multiple supercells may develop
    with gradual erosion of lingering MLCIN and weak ascent preceding
    the ejecting shortwave trough. Any supercells that can root and
    ingest the ample low-level moisture will be capable of producing
    very large hail (2-3+ inches in diameter) given a overall rather
    favorable environment. The tornado potential is less clear through
    the day, but a southerly low-level jet will quickly strengthen this
    evening and aid curved/elongated hodographs with strong effective
    SRH. A somewhat conditional/uncertain threat for a couple of strong
    tornadoes remains apparent, especially if any supercells that can
    form this afternoon persist into the evening.

    Additional, somewhat elevated supercells may form this evening into
    tonight along/north of the warm front from northern Oklahoma near
    the triple point into Kansas. This activity will also pose a threat
    for large to very large hail and possibly an increasing
    tornado/damaging wind risk.

    Farther south into Texas, the forcing for ascent will remain
    weak/nebulous along the dryline. Still, some potential for a few
    supercells is apparent across north-central Texas where the greatest
    heating and minimal MLCIN is forecast to exist. Large to very large
    hail should be the main threat with any splitting supercells that
    can develop this afternoon along/east of the dryline and be
    sustained.

    ..Guyer/Barnes.. 04/26/2026

    $$

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  • From COD Weather Processor@1:2320/107 to wx-storm@lists.illinois.edu on Sunday, April 26, 2026 20:01:03
    ACUS01 KWNS 262000
    SWODY1
    SPC AC 261958

    Day 1 Convective Outlook
    NWS Storm Prediction Center Norman OK
    0258 PM CDT Sun Apr 26 2026

    Valid 262000Z - 271200Z

    ...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS OVER MUCH OF
    CENTRAL AND EASTERN KANSAS INTO FAR NORTHERN OKLAHOMA AND FAR
    WESTERN MISSOURI...

    ...SUMMARY...
    Scattered severe thunderstorms with large to very large hail,
    damaging winds and tornadoes are expected this afternoon through
    tonight across parts of the southern/central Plains to Lower
    Missouri Valley. A couple of strong tornadoes and hailstones up to
    2-3 inches in diameter are possible.

    ...20Z Update...
    The forecast (see below) remains generally on track. The main
    changes made to this outlook were to expand severe probabilities
    farther to the east to account for an uptick in severe potential
    later tonight, as depicted by some of the latest high-resolution
    guidance.

    Overall, uncertainties remain regarding precisely where the
    strongest storms are going to occur. OK Mesonet data over the past
    few hours have depicted some lowering of dewpoints in west-central
    OK, with a slightly diminished CU field noted. However, several
    guidance members depict supercellular development in the 02-06Z
    period over northern OK, likely in part to the strengthening of a
    low-level jet. Given impressive shear profiles and 8.5-9 C/km
    mid-level lapse rates expected in this region overnight, it is
    plausible that the strongest storms for the remainder of the period
    (to 12Z Monday morning) may occur here, with 2+ inch diameter hail
    and perhaps strong tornadoes. The primary uncertainty for
    introducing higher tornado probabilities over northern OK is the
    possible late storm initiation and associated boundary layer
    stabilization, which may dampen the robustness of tornado production
    with these storms.

    Visible satellite imagery depicts more agitated CU centered over
    Baylor County, TX, which may hint at locally higher/less conditional
    severe threat across far north-central TX later this afternoon and
    evening. However, synoptic forcing is weak, and if storms form, they
    will likely be sparse, precluding the addition of higher severe
    probabilities in this region at this time.

    ..Squitieri.. 04/26/2026

    .PREV DISCUSSION... /ISSUED 1154 AM CDT Sun Apr 26 2026/

    ...Southern/Central Plains to the Mid Mississippi Valley...
    Appreciable severe potential is still readily apparent especially
    later this afternoon into tonight, although sub-regional details
    remain quite complex, particularly regarding the southern extent of
    deep convective initiation southward along the dryline.

    A weak lead mid-level vorticity maximum over the central High Plains
    early today will continue to aid elevated thunderstorm development
    across Kansas through the afternoon. See Mesoscale Discussion 547
    for short-term details. Increasing MUCAPE with persistent low-level
    warm/moist advection and steepening mid-level
    lapse rates combined with strong deep-layer shear will support
    organized updrafts, including the potential for supercells. This
    convection will probably tend to remain elevated to the north of a
    front as it spreads east-northeastward over the central Plains, but
    scattered large hail may occur given the overall favorable
    environment. Isolated 2+ inch diameter hail also appears possible
    with the strongest cores. Eventually, this activity may pose a
    greater threat for damaging winds across eastern Kansas into western
    Missouri by late afternoon/early evening.

    A more notable mid-level shortwave trough is expected to eject
    northeastward across the Southwest and southern/central High Plans
    today, accompanied by a 50-60 kt southwesterly mid-level jet. Weak
    lee cyclogenesis is forecast to occur across the southeast
    Colorado/northeast New Mexico vicinity in response, with the surface
    low developing into the Oklahoma Panhandle and southwest Kansas by
    this evening. Strong to locally extreme instability is forecast to
    develop east of a sharpening dryline across western/central Oklahoma
    as daytime heating of a moist airmass occurs. There is still a fair
    amount of uncertainty with the placement of an effective warm front
    by late afternoon/early evening, but current expectations are for
    this boundary to be draped somewhere near north-central Oklahoma by
    peak afternoon heating. The surface triple point may serve as a
    focus for convective initiation later today into this evening,
    although better large-scale ascent associated with the mid-level
    shortwave trough overspreading the warm sector will be delayed until
    this evening and past peak diurnal heating.

    Greater than average uncertainty exists regarding the potential for surface-based convective initiation today in Oklahoma/north Texas,
    but the volatile environment and ample conditional-type potential is concerning. It appears possible that multiple supercells may develop
    with gradual erosion of lingering MLCIN and weak ascent preceding
    the ejecting shortwave trough. Any supercells that can root and
    ingest the ample low-level moisture will be capable of producing
    very large hail (2-3+ inches in diameter) given a overall rather
    favorable environment. The tornado potential is less clear through
    the day, but a southerly low-level jet will quickly strengthen this
    evening and aid curved/elongated hodographs with strong effective
    SRH. A somewhat conditional/uncertain threat for a couple of strong
    tornadoes remains apparent, especially if any supercells that can
    form this afternoon persist into the evening.

    Additional, somewhat elevated supercells may form this evening into
    tonight along/north of the warm front from northern Oklahoma near
    the triple point into Kansas. This activity will also pose a threat
    for large to very large hail and possibly an increasing
    tornado/damaging wind risk.

    Farther south into Texas, the forcing for ascent will remain
    weak/nebulous along the dryline. Still, some potential for a few
    supercells is apparent across north-central Texas where the greatest
    heating and minimal MLCIN is forecast to exist. Large to very large
    hail should be the main threat with any splitting supercells that
    can develop this afternoon along/east of the dryline and be
    sustained.

    $$

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  • From COD Weather Processor@1:2320/107 to wx-storm@lists.illinois.edu on Monday, April 27, 2026 01:06:35
    ACUS01 KWNS 270106
    SWODY1
    SPC AC 270105

    Day 1 Convective Outlook
    NWS Storm Prediction Center Norman OK
    0805 PM CDT Sun Apr 26 2026

    Valid 270100Z - 271200Z

    ...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS CENTRAL/EASTERN KANSAS...NORTHERN OKLAHOMA...FAR WESTERN MISSOURI...

    ...SUMMARY...
    Scattered severe thunderstorms with large to very large hail,
    damaging winds and tornadoes are expected tonight across parts of
    the southern/central Plains to Lower Missouri Valley. A couple of
    strong tornadoes and hailstones up to 2-3 inches in diameter are
    possible.

    ...01Z Update...
    A prominent shortwave trough now nearing the Colorado/Kansas border
    is promoting elevated convection ahead of it. An 8.2 C/km mid-level
    lapse rate was sampled on the 00Z DDC sounding this evening. These
    steep lapse rates should shift eastward along with the shortwave
    trough. Additional, stronger convection remains possible in parts of central/eastern Kansas into northern Oklahoma. Earlier convection
    has complicated the low-level thermodynamic environment, though
    large hail and damaging winds are possible with organized cells and
    linear structures. The tornado threat through the evening is
    somewhat less clear, but a deepening surface low should advect
    richer moisture northward. Depending on storm mode and low-level
    stability, tornadoes remain possible in parts of northern Oklahoma
    and south-central Kansas later this evening. In the short term, the
    greatest threat for a strong tornado is in southeast Kansas. In
    Oklahoma into North Texas, the dryline is surging westward. This
    area will become increasingly removed from large-scale ascent. An
    isolated storm or two remain possible at least trough mid-evening.
    Lastly, convection in Missouri and southeast Kansas will eventually
    grow upscale. A buoyancy gradient within the Mid-South region may
    serve as a focus for continued southeast movement through the
    evening. Marginal wind and hail are possible with this activity.

    ..Wendt.. 04/27/2026

    $$

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  • From COD Weather Processor@1:2320/107 to wx-storm@lists.illinois.edu on Monday, April 27, 2026 06:01:37
    ACUS01 KWNS 270601
    SWODY1
    SPC AC 270600

    Day 1 Convective Outlook
    NWS Storm Prediction Center Norman OK
    0100 AM CDT Mon Apr 27 2026

    Valid 271200Z - 281200Z

    ...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS PORTIONS OF THE MID-MISSISSIPPI VALLEY INTO THE LOWER OHIO VALLEY AND PARTS OF THE
    MID-SOUTH...

    ...SUMMARY...
    Widespread strong to severe thunderstorm development appears
    probable across the middle Mississippi into lower Ohio Valleys this
    afternoon through this evening, accompanied by potential for a few
    strong tornadoes, damaging wind gusts and large hail.

    ...Synopsis...
    Water vapor imagery shows a prominent shortwave trough promoting
    elevated strong to severe convection across central and eastern
    Kansas. This activity is expected to move north and eastward through Iowa/Missouri/Wisconsin/northern Illinois into daybreak and perhaps
    part of the afternoon for some areas. The outflow from this
    convection should act to limit the northern extent of greater
    destabilization during the afternoon and thus the greatest severe
    threat. A surface low will track northeastward along the parent
    shortwave. Though this low has trended downward in intensity in
    recent model runs, strong low-level wind fields are expected within
    the warm sector throughout the day and into the evening. Areas of
    pre-frontal convergence and a cold front will be the focus for
    convective development along with more strongly forced convection
    tied to the shortwave trough. The front will be draped south and
    westward into the Ozarks and the southern Plains.

    ...Mid-Mississippi Valley/Lower Ohio Valley...
    As mentioned, surface based buoyancy will be limited by early day
    activity. The current expectation is for parts of central/eastern
    Missouri into central/southern Illinois and western Kentucky to see
    greater destabilization. There is activity ongoing within central
    Missouri early this morning that may have some impact, however. This
    is the source of greatest uncertainty for these regions. The
    kinematic environment will certainly be favorable for supercells.
    The moderate to strong 850 mb jet will also lead to potential for
    several tornadoes, some of which could be strong. Lapse rates at
    mid-levels will be rather steep. Large to very-large hail potential
    is evident given the long hodographs. Some upscale growth into one
    or more linear segments is expected to occur. This will increase
    the threat for damaging winds. An increase in tornado probabilities
    was considered. Given the questions regarding early day convection
    and where favorable convergence zones/outflow boundaries might be
    located reduces confidence. Convective trends into daybreak will
    need to be closely monitored.

    ...Mid-South...
    Models indicate potential for supercells along the cold front and
    even potentially ahead of it. Forcing for ascent will be weaker, but
    this may help to keep activity cellular longer. Some of this
    activity could develop after 00Z. Mid-level lapse rates are expected
    to be steep enough and mid-level flow strong enough to support large
    to potentially very large hail and damaging winds. The tornado
    threat will likely be lower given the time of day and tendency for
    storms to be at least slightly elevated.

    ...Upper Midwest...
    Observational and model trends suggest destabilization will be more
    limited on account of convection at daybreak and beyond. Even so,
    strong low-level and effective shear will still allow storms to be
    organized and capable of large hail, damaging winds and a couple
    tornadoes. There will be potential for both convection at daybreak
    and also during the afternoon. The greatest potential for afternoon
    supercells would be in parts of eastern Iowa along with the surface
    low and colder air aloft.

    ...Western/central Texas...
    As moisture returns westward during the evening, some model guidance
    suggest convection might try to develop along the retreating
    dryline. Buoyancy and shear would support a threat for large hail
    and perhaps severe winds. However, mid-level ascent will be very
    weak and models generally do not sustain these convective attempts.
    Severe probabilities may be needed if confidence in development
    increases.

    ..Wendt/Moore.. 04/27/2026

    $$

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  • From COD Weather Processor@1:2320/107 to wx-storm@lists.illinois.edu on Monday, April 27, 2026 12:47:09
    ACUS01 KWNS 271247
    SWODY1
    SPC AC 271245

    Day 1 Convective Outlook
    NWS Storm Prediction Center Norman OK
    0745 AM CDT Mon Apr 27 2026

    Valid 271300Z - 281200Z

    ...THERE IS A MODERATE RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF
    MISSOURI INTO ILLINOIS...

    ...SUMMARY...
    Numerous severe thunderstorms are expected from the mid
    Mississippi/lower Ohio Valleys into the Mid-South through this
    evening, with a threat for multiple strong to intense tornadoes
    (EF-3+), widespread severe/damaging wind gusts, and scattered large
    to very large hail.

    ...Mid Mississippi Valley/Midwest into the Mid-South/Lower
    Mississippi Valley...
    An active severe weather day is forecast for much of the mid MS
    Valley/lower OH Valleys into the Mid-South. Ongoing thunderstorms
    this morning complicate the overall scenario to some extent, but a
    very favorable corridor for intense supercells and strong tornadoes
    is apparent this afternoon/evening across parts of MO into IL, where
    a Moderate Risk (Level 4 of 5) has been introduced.

    Elevated supercells with mainly a hail threat should persist for at
    least a couple more hours this morning across the mid MS Valley as
    strong low-level warm advection aids in continued influx of
    sufficient MUCAPE amid strong deep-layer shear. Multiple
    clusters/embedded supercells are also ongoing this morning across
    western into northern MO. This activity should pose a greater threat
    for scattered severe/damaging winds, along with some hail risk. The
    tornado threat in the short term (this morning) remains unclear, but
    it should eventually increase as the boundary-layer across central
    MO continues to gradually destabilize/moisten. See Mesoscale
    Discussion 565 for more details on the near-term severe risk with
    these ongoing thunderstorms.

    Current expectations are for the greatest severe risk to focus south
    of these morning thunderstorms. A mid/upper-level trough will eject northeastward from the northern/central Plains into the Midwest and
    mid MS Valley through the period. Low-level mass response will
    encourage the primary surface low to consolidate across MN/WI by
    this evening, with an effective warm front delineated by the morning convection. Aided by daytime heating and steep mid-level lapse
    rates, a moderately to strongly unstable airmass is expected to be
    in place by early to mid afternoon across much of central
    MO/southern IL southward into the Mid-South and lower MS Valley.

    Strengthening west-southwesterly flow aloft associated with a 50-70
    kt mid-level jet will overspread much of the warm sector by peak
    heating, and a 35-45 kt south-southwesterly low-level jet will both
    provide ample low-level and deep-layer shear to support supercells.
    Initially discrete surface-based development appears likely to occur
    by 19-21Z across the mid MS Valley/Mid-South ahead of the surface
    cold front, and perhaps along weak low-level confluence zones in the
    open warm sector.

    These supercells will exist in a very favorable environment for
    tornadoes through the afternoon and evening, and multiple strong to
    intense tornadoes (EF-2/3+) appear likely, especially from parts of
    MO into IL along/near the effective front. This strong tornado
    threat may also extend farther south into AR/TN, but confidence is
    somewhat lower with southward extent due to weaker large-scale
    forcing. Large to very large hail (2-3 inches in diameter) may also
    occur with any sustained supercells.

    By early evening, convection will probably tend to consolidate into
    clusters capable of producing numerous to widespread damaging winds
    from the mid MS Valley eastward into the lower OH Valley, before
    eventually weakening tonight as instability gradually decreases. A
    threat for QLCS and embedded supercell tornadoes will persist
    through much of the evening and early overnight hours as well given
    strong low-level shear forecast.

    To the north of the ongoing morning convection across IA/northern
    IL/WI, a lesser (but non-zero) severe risk is forecast. This region
    will have less instability this afternoon, but strong shear. Have
    maintained the Marginal/Slight Risks for the possibility of isolated
    to locally scattered hail/damaging winds, and perhaps a couple of
    tornadoes.

    ...ArkLaTex into Texas...
    Confidence in sustained convection occurring from the ArkLaTex
    southward into TX is lower compared to locations farther north. But,
    strong heating ahead of a surface dryline could support isolated to
    scattered supercells capable of producing large to very large hail
    and occasional damaging winds. Increasing low-level warm/moist
    advection tonight could foster additional robust thunderstorms along
    the retreating dryline and eventually the southward-moving cold
    front. Severe probabilities have been expanded across these regions
    to account for this potential.

    ..Gleason/Thornton.. 04/27/2026

    $$

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  • From COD Weather Processor@1:2320/107 to wx-storm@lists.illinois.edu on Monday, April 27, 2026 16:51:41
    ACUS01 KWNS 271651
    SWODY1
    SPC AC 271650

    Day 1 Convective Outlook
    NWS Storm Prediction Center Norman OK
    1150 AM CDT Mon Apr 27 2026

    Valid 271630Z - 281200Z

    ...THERE IS A MODERATE RISK OF SEVERE THUNDERSTORMS ACROSS
    EAST/SOUTHEAST MISSOURI...SOUTHERN ILLINOIS...WESTERN KENTUCKY...AND
    NORTHWEST TENNESSEE...

    ...SUMMARY...
    Numerous severe thunderstorms are expected from the mid
    Mississippi/lower Ohio Valleys into the Mid-South through this
    evening, with a threat for multiple strong to intense tornadoes
    (EF3+), widespread severe/damaging wind gusts, and scattered large
    to very large hail.

    ...Mid Mississippi Valley/Midwest into the Mid-South/Lower
    Mississippi Valley...
    Forecast scenario largely unchanged in that a very active severe-weather/tornado day is expected regionally, especially into
    late afternoon and this evening. Initially, a relatively long-lived
    linear cluster of convection persists at late morning across east-central/south-central Illinois, with additional initially
    elevated storms on its eastern/southern periphery, moving from
    eastern Illinois into Indiana, with severe hail and damaging winds
    persisting as early day hazards.

    Over time, air mass will continue to moisten and rapidly destabilize along/south of the MCS-associated outflow from central Missouri into south-central Illinois. A mid/upper-level trough will eject
    northeastward from the northern/central Plains into the Midwest and
    middle Mississippi Valley through the period. Low-level mass
    response will encourage the primary surface low to consolidate
    across Minnesota/Wisconsin by this evening, with a warm front
    effectively delineated by the morning convection.

    Strengthening west-southwesterly flow aloft associated with a 50-70
    kt mid-level jet will overspread much of the warm sector by peak
    heating, and a 35-45 kt south-southwesterly low-level jet will both
    provide ample low-level and deep-layer shear to support supercells.
    Initially discrete surface-based development appears likely to occur
    into mid-afternoon across the mid Mississippi Valley/Mid-South ahead
    of the surface cold front, and perhaps along weak low-level
    confluence zones in the open warm sector including generally near
    the confluence of the Mississippi/Ohio Rivers southward into the
    Mid-South.

    These supercells will exist in a very favorable environment for
    tornadoes through the afternoon and evening, and multiple strong to
    intense tornadoes (EF2/3+) appear likely, especially from parts of
    Missouri into Illinois along/near the effective front. This strong
    tornado potential will also likely extend farther south within the
    warm sector into the Mid-South.

    By early evening, convection will probably tend to consolidate into
    clusters of supercells and then more linear segments with some
    increase in damaging wind potential aside from large hail and a
    continued multi-mode tornado risk tonight.

    ...ArkLaTex into Texas...
    While storm coverage may trend lesser with southwest extent, the
    potential for at least isolated intense storms will exist across the
    region. Supercells capable of producing large to very large hail and
    occasional damaging winds are expected. Increasing low-level
    warm/moist advection tonight could foster additional robust
    thunderstorms along the retreating dryline and eventually the
    southward-moving cold front.

    ..Guyer/Weinman.. 04/27/2026

    $$

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  • From COD Weather Processor@1:2320/107 to wx-storm@lists.illinois.edu on Monday, April 27, 2026 19:51:18
    ACUS01 KWNS 271951
    SWODY1
    SPC AC 271949

    Day 1 Convective Outlook
    NWS Storm Prediction Center Norman OK
    0249 PM CDT Mon Apr 27 2026

    Valid 272000Z - 281200Z

    ...THERE IS A MODERATE RISK OF SEVERE THUNDERSTORMS ACROSS
    EAST/SOUTHEAST MISSOURI...SOUTHERN ILLINOIS...WESTERN KENTUCKY...AND
    NORTHWEST TENNESSEE...

    ...SUMMARY...
    Numerous severe thunderstorms are expected from the mid
    Mississippi/lower Ohio Valleys into the Mid-South through this
    evening, with a threat for multiple strong to intense tornadoes
    (EF3+), widespread severe/damaging wind gusts, and scattered large
    to very large hail.

    ...20z Update...
    Only minor adjustments were made to extend the Marginal Risk back
    into southeastern Kansas/northeastern Oklahoma to account for storms
    initiating over the last hour.

    The Moderate Risk remains unchanged with this update. The morning
    MCS is now moving through eastern Illinois/southern Indiana. Further
    west in Missouri and western Illinois, modifying remnant outflow
    remains near the St. Louis Metro. Cumulus south of this boundary
    across southeastern Missouri into southern Illinois, cumulus within
    the warm sector is deepening. Increasing MLCAPE/steepening lapse
    rates are nosing northward in southern central Missouri and
    south-central Illinois.

    Just to the west of the Mississippi River, radar shows occasional
    attempts at initiation within the open warm sector. While the
    details continue to evolve, it likely that a corridor of conditional
    threat for strong-intense tornadoes will develop from the Missouri
    Bootheel into southern Illinois/western Kentucky. Within this region
    strong daytime heating has led to a volatile air mass, with moderate
    to strong MLCAPE 2000-3000 J/kg and strong deep layer shear. VAD
    profiles frm PAH (Paducah, KY) and LSX (St. Louis, MO) indicate a
    rich SRH environment of around 200-300 m2/s2 in the 0-1 km layer. It
    is likely that supercells capable of all hazards, including
    strong-intense tornadoes, large to very large hail, and damaging
    winds. Will develop across this region soon. See MCD571 for
    additional information.

    The conditional threat for strong tornadoes will extend as far south
    as the Arklatex into portions of western Tennessee. Through time,
    storm mode will shift to become linear with the southward moving
    front, which will bring an increase into the evening of damaging
    wind threat. Line embedded tornadoes, some of which may be strong,
    will continue to be a threat into the evening.

    ..Thornton.. 04/27/2026

    .PREV DISCUSSION... /ISSUED 1150 AM CDT Mon Apr 27 2026/

    ...Mid Mississippi Valley/Midwest into the Mid-South/Lower
    Mississippi Valley...
    Forecast scenario largely unchanged in that a very active severe-weather/tornado day is expected regionally, especially into
    late afternoon and this evening. Initially, a relatively long-lived
    linear cluster of convection persists at late morning across east-central/south-central Illinois, with additional initially
    elevated storms on its eastern/southern periphery, moving from
    eastern Illinois into Indiana, with severe hail and damaging winds
    persisting as early day hazards.

    Over time, air mass will continue to moisten and rapidly destabilize along/south of the MCS-associated outflow from central Missouri into south-central Illinois. A mid/upper-level trough will eject
    northeastward from the northern/central Plains into the Midwest and
    middle Mississippi Valley through the period. Low-level mass
    response will encourage the primary surface low to consolidate
    across Minnesota/Wisconsin by this evening, with a warm front
    effectively delineated by the morning convection.

    Strengthening west-southwesterly flow aloft associated with a 50-70
    kt mid-level jet will overspread much of the warm sector by peak
    heating, and a 35-45 kt south-southwesterly low-level jet will both
    provide ample low-level and deep-layer shear to support supercells.
    Initially discrete surface-based development appears likely to occur
    into mid-afternoon across the mid Mississippi Valley/Mid-South ahead
    of the surface cold front, and perhaps along weak low-level
    confluence zones in the open warm sector including generally near
    the confluence of the Mississippi/Ohio Rivers southward into the
    Mid-South.

    These supercells will exist in a very favorable environment for
    tornadoes through the afternoon and evening, and multiple strong to
    intense tornadoes (EF2/3+) appear likely, especially from parts of
    Missouri into Illinois along/near the effective front. This strong
    tornado potential will also likely extend farther south within the
    warm sector into the Mid-South.

    By early evening, convection will probably tend to consolidate into
    clusters of supercells and then more linear segments with some
    increase in damaging wind potential aside from large hail and a
    continued multi-mode tornado risk tonight.

    ...ArkLaTex into Texas...
    While storm coverage may trend lesser with southwest extent, the
    potential for at least isolated intense storms will exist across the
    region. Supercells capable of producing large to very large hail and
    occasional damaging winds are expected. Increasing low-level
    warm/moist advection tonight could foster additional robust
    thunderstorms along the retreating dryline and eventually the
    southward-moving cold front.

    $$

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  • From COD Weather Processor@1:2320/107 to wx-storm@lists.illinois.edu on Tuesday, April 28, 2026 01:01:49
    ACUS01 KWNS 280101
    SWODY1
    SPC AC 280059

    Day 1 Convective Outlook
    NWS Storm Prediction Center Norman OK
    0759 PM CDT Mon Apr 27 2026

    Valid 280100Z - 281200Z

    ...THERE IS A MODERATE RISK OF SEVERE THUNDERSTORMS FOR PORTIONS OF SOUTHEASTERN MISSOURI INTO FAR SOUTHERN ILLINOIS AND WESTERN
    KENTUCKY...

    ...SUMMARY...
    Severe storms should continue through tonight with a wind and hail
    threat. A few tornadoes may still occur, and a couple of strong
    tornadoes remain possible.

    ...Synopsis...
    A negatively tilted 500 mb mid-level trough continues to traverse
    the Upper Midwest in tandem with a surface low, supporting a surface
    cold front to sweep across the Mid-MS Valley. A persistent elongated
    convective system has materialized along the cold front, accompanied
    by several embedded and preceding supercells. These storms have a
    collective history of severe wind and hail, with some stones
    reaching the 2-3 inch diameter range.

    Upper 60s to low 70s F surface dewpoints, beneath 8+ C/km mid-level
    lapse rates, resides ahead of the cold front/storms, yielding over
    3000 J/kg MLCAPE in spots. Meanwhile, strong mid-level flow
    associated with a speed max is overspreading an intensifying (45+
    kt) southwesterly low-level jet, resulting in 50+ kts of effective
    bulk shear and large/curved low-level hodographs with 300-500 m2/s2
    effective SRH (per 00Z mesoanalysis and regional VADs). Supercells
    have failed to organize and produce tornadoes up to this point.
    However, storms along/ahead of the cold front will continue to
    advance eastward toward the low-level jet/shear axis. Therefore, an
    uptick in tornado activity may still occur early tonight, especially
    with any discrete, sustained supercells that can develop. Discrete
    storms may also be accompanied by severe hail, with severe wind
    gusts likely with continued linear storm modes.

    ..Squitieri.. 04/28/2026

    $$

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  • From COD Weather Processor@1:2320/107 to wx-storm@lists.illinois.edu on Tuesday, April 28, 2026 06:01:49
    ACUS01 KWNS 280601
    SWODY1
    SPC AC 280559

    Day 1 Convective Outlook
    NWS Storm Prediction Center Norman OK
    1259 AM CDT Tue Apr 28 2026

    Valid 281200Z - 291200Z

    ...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS FOR PORTIONS OF
    NORTHERN TEXAS INTO THE LOWER MISSISSIPPI VALLEY...

    ...SUMMARY...
    Multiple rounds of strong to severe thunderstorms are likely across
    parts Texas into the lower Mississippi and Tennessee Valleys this
    afternoon and evening. Very large hail, swaths of damaging wind, and
    a few tornadoes are possible.

    ...Synopsis...
    A series of mid-level troughs, embedded within a broader
    low-amplitude mid-level flow regime, will traverse the central U.S.
    today. A surface low and associated cold front will continue to
    progress across the OH Valley toward the East Coast during the day.
    However, the approach of another mid-level trough over the Ozark
    Valley region will encourage either a weak surface low or surface
    trough to develop over central TX. This will stall the southward
    progression of the surface cold front given appreciable low-level warm-air/moisture advection. Seasonally cold air aloft and
    accompanying upper support from multiple embedded mid-level
    perturbations will overspread the warm-air advection regime,
    supporting several rounds of thunderstorms. Given strong vertical
    wind shear over the warm sector, severe storms are likely,
    especially over portions of the southern Plains toward the TN
    Valley.

    ...Portions of northern TX into the TN Valley...
    A complex severe weather scenario is expected across TX into the TN
    Valley through the period, with multiple rounds of severe
    thunderstorms likely. The first round of storms is currently
    initiating over western TX, and may increase in coverage between
    12-18Z across central OK into northern TX as a lead mid-level
    impulse traverses a WAA regime. 7-8 C/km mid-level lapse rates amid
    50+ kts of effective bulk shear will support elevated multicells
    capable of producing severe hail. These storms will progress across
    the MS Valley through the day. Some guidance indicates that these
    storms may evolve into an MCS by afternoon, accompanied by a
    damaging gust threat over the Gulf coast states.

    Regardless of the evolution of earlier storms, guidance consensus
    depicts adequate clearing behind this initial wave over TX into the
    Ozark Valley region. Strong surface heating will encourage surface
    temperatures to reach 90 F in some locales, amid 70+ F surface
    dewpoints. Given 8-9 C/km mid-level lapse rates, MLCAPE should reach
    the 2500-4000 J/kg range by mid to late afternoon. By this time, the
    primary mid-level trough will overspread the southern Plains,
    promoting enough deep-layer ascent for another round of storms to
    initiate. Given 50 kts of effective bulk shear and initially
    straight hodographs, supercells are expected, accompanied by a
    severe hail threat. The most intense supercells may develop over
    northern TX and progress eastward, and will be capable of producing
    severe hail as large as 3-4 inches in diameter. Given a lingering
    low-level jet (supporting elongated hodographs with some low-level
    curvature) over the Sabine River Valley, a few dominant/right-moving
    supercells may produce a few tornadoes, though the tornado threat
    will be conditional on adequate boundary-layer
    mixing/destabilization. Later in the afternoon/early evening, severe hail/isolated tornado producing supercells may merge into an MCS,
    accompanied by a severe wind threat across the Lower MS Valley.

    ...Portions of central into southern TX...
    Forcing for ascent will be weak across portions of central into
    southwestern TX. Nonetheless, 8-9 C/km mid-level lapse rates will
    overspread a well-mixed boundary layer. Tropospheric speed shear
    exceeding 40 kts will yield elongated hodographs, so any storm that
    can initiate, mature, and sustain itself should be supercellular in
    nature, accompanied by a severe hail threat. Any instance of hail
    with these storms may include stones exceeding 2 inches in diameter.
    Since a second, low-amplitude mid-level impulse will overspread
    western and central TX toward the end of the period, isolated
    supercell initiation will be possible across portions of central
    into southwestern TX late this afternoon into early (12Z) Wednesday
    morning.

    ..Squitieri/Moore.. 04/28/2026

    $$

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  • From COD Weather Processor@1:2320/107 to wx-storm@lists.illinois.edu on Tuesday, April 28, 2026 12:02:51
    ACUS01 KWNS 281202
    SWODY1
    SPC AC 281200

    Day 1 Convective Outlook
    NWS Storm Prediction Center Norman OK
    0700 AM CDT Tue Apr 28 2026

    Valid 281300Z - 291200Z

    ...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF
    THE SOUTHERN PLAINS INTO THE LOWER MISSISSIPPI VALLEY AND
    MID-SOUTH...

    ...SUMMARY...
    Multiple rounds of severe thunderstorms will occur across parts of
    the southern Plains into the lower Mississippi/Tennessee Valleys and
    Southeast through this evening. Very large to giant hail (2-4+
    inches), swaths of severe/damaging winds, and a few tornadoes are
    all possible.

    ...Southern Plains into the Lower Mississippi Valley/Southeast...
    With large-scale upper troughing anchored over the Plains and
    central Canada, an embedded mid-level shortwave trough will eject
    eastward across the southern/central Plains to the lower/mid MS
    Valleys by this evening. Rich low-level moisture continues to spread
    northward from TX into southern OK this morning in tandem with a
    low-level jet, and this trend should continue downstream into the
    lower MS Valley through the day as a warm front lifts northward to a
    weak surface low across the Ozarks. Another surface low will remain
    over northwest TX, with a dryline extending southwestward to the Big
    Bend region.

    A strongly unstable airmass exists across the southern Plains to the
    ArkLaTex, along and near a slowly retreating/northward-returning
    warm front. Elevated supercells are ongoing across western north TX.
    This activity is being aided by lift and strong deep-layer shear
    associated with the ejecting mid-level shortwave trough, and
    low-level warm/moist advection. Current expectations are for these
    supercells to continue posing a threat for mainly large to very
    large hail through the rest of the morning as they spread
    east-northeastward across north TX/southern OK. But, eventual
    clustering and a greater damaging wind threat may materialize into
    the afternoon as this convection crosses the front and accesses
    greater instability across AR and the Ozarks.

    Additional surface-based convective development is forecast near the
    triple point in north-central TX towards the ArkLaTex this
    afternoon, where extreme instability (4000+ J/kg MLCAPE) and very
    strong deep-layer shear (50-60+ kt) will support the potential for
    multiple intense supercells. Very large to giant hail (2-4+ inches)
    may occur with the strongest supercells given the overall very
    favorable environment and presence of steep mid-level lapse rates.
    Some tornado threat may also exist with these supercells, even
    though low-level shear is not forecast to be overly strong.

    Numerous to widespread convection across the Mid-South to southern
    Appalachians has generally diminished in intensity this morning. In
    its wake, airmass recovery is anticipated today across the lower MS
    Valley and Mid-South. A convectively reinforced front/outflow
    boundary from the morning thunderstorms should attempt to lift
    northward some through the day, with the greater instability
    forecast across the lower MS Valley where steep mid-level lapse
    rates are in place. Convective evolution across these areas through
    the evening remains unclear, but multiple rounds of supercells and
    multicell clusters capable of producing large hail, scattered to
    numerous damaging winds, and perhaps a few tornadoes appear likely.
    Less instability is forecast to the north of the ongoing convection
    across the TN Valley, but some airmass recovery and severe threat
    still appears possible by late afternoon/early evening.

    ..Gleason/Jewell.. 04/28/2026

    $$

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  • From COD Weather Processor@1:2320/107 to wx-storm@lists.illinois.edu on Tuesday, April 28, 2026 16:53:27
    ACUS01 KWNS 281653
    SWODY1
    SPC AC 281651

    Day 1 Convective Outlook
    NWS Storm Prediction Center Norman OK
    1151 AM CDT Tue Apr 28 2026

    Valid 281630Z - 291200Z

    ...THERE IS A MODERATE RISK OF SEVERE THUNDERSTORMS ACROSS NORTH
    TEXAS...

    ...SUMMARY...
    Multiple rounds of severe thunderstorms will occur across parts of
    the southern Plains into the lower Mississippi/Tennessee Valleys and
    Southeast through this evening. Very large to giant hail (2-4+
    inches), swaths of severe/damaging winds, and a few tornadoes are
    all possible.

    ...Southern Plains to Lower Mississippi Valley/Southeast...
    Have upgraded portions of North Texas to a Moderate Risk for what is anticipated to be a semi-focused sub-regional corridor of supercells
    including very large hail potential along with some damaging
    wind/tornado risk centered on mid-afternoon through
    early/mid-evening.

    First, a loosely organized complex of storms continues to progress east-northeastward along the Red River of southeast
    Oklahoma/northeast Texas and broader parts of eastern Oklahoma at
    late morning. Additional increasingly surface-based development
    seems probable on this near-frontal zone and associated moist axis
    and thermal gradient that extends east-northeastward to the Mid-South/ArkLaMiss. This may include supercells as well as the
    possibility of an upscale-growing complex. Other initially elevated
    severe storms are expected to continue and increase today from
    northeast Oklahoma across the Ozarks toward parts of the
    Mid-South/Mississippi Valley. Large hail is the initial risk, but a surface-based storm risk could develop pending boundary layer
    warming.

    Broadly speaking outside on ongoing storms, a strongly unstable
    airmass exists across the southern Plains to the ArkLaTex, along and
    near a slowly retreating/northward-returning warm front. This is
    beneath relatively strong winds aloft, particularly in
    mid/high-levels based on morning upper-air data. Additional intense surface-based convective development is forecast near the triple
    point in north-central Texas towards the ArkLaTex this afternoon,
    where extreme instability (4000+ J/kg MLCAPE) and very strong
    deep-layer shear (50-60+ kt) will support the potential for multiple
    intense supercells. Very large to giant hail (2-4+ inches) may occur
    with the strongest supercells given the overall very favorable
    environment and presence of steep mid-level lapse rates. Some
    tornado threat may also exist with these supercells, even though
    low-level shear is not forecast to be overly strong.

    Additional severe storms are expected as far east as Mississippi and
    Alabama today -- see Mesoscale Discussion 594 for short-term
    details. An additional secondary round of upscale-growing storms
    with increasing damaging wind potential could also move into this
    same region late today, or more so tonight.

    ..Guyer/Chalmers.. 04/28/2026

    $$

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  • From COD Weather Processor@1:2320/107 to wx-storm@lists.illinois.edu on Tuesday, April 28, 2026 20:02:28
    ACUS01 KWNS 282002
    SWODY1
    SPC AC 282000

    Day 1 Convective Outlook
    NWS Storm Prediction Center Norman OK
    0300 PM CDT Tue Apr 28 2026

    Valid 282000Z - 291200Z

    ...THERE IS A MODERATE RISK OF SEVERE THUNDERSTORMS ACROSS NORTH
    TEXAS...

    ...SUMMARY...
    Multiple rounds of severe thunderstorms will occur across parts of
    the southern Plains into the lower Mississippi/Tennessee Valleys and
    Southeast through this evening. Very large to giant hail (2-4+
    inches), swaths of severe/damaging winds, and a few tornadoes are
    all possible.

    ...20Z Update...
    The previous forecast remains on track, and only minor adjustments
    were made with this update. Most noteworthy, the CIG2 (intensity
    level 2/2) hail area was expanded northward into south-central OK,
    where robust splitting supercells are evolving in an environment
    characterized by 2500-3000 J/kg MLCAPE and around 50 kt of effective
    shear. These storms will continue to pose a risk of very large hail
    through the afternoon. In north TX, a corridor of relatively higher
    tornado potential is evident along a remnant outflow boundary --
    where low-level shear is locally enhanced. Refer to Tornado Watch
    171 and MCD 599 for more information.

    ..Weinman.. 04/28/2026

    .PREV DISCUSSION... /ISSUED 1151 AM CDT Tue Apr 28 2026/

    ...Southern Plains to Lower Mississippi Valley/Southeast...
    Have upgraded portions of North Texas to a Moderate Risk for what is anticipated to be a semi-focused sub-regional corridor of supercells
    including very large hail potential along with some damaging
    wind/tornado risk centered on mid-afternoon through
    early/mid-evening.

    First, a loosely organized complex of storms continues to progress east-northeastward along the Red River of southeast
    Oklahoma/northeast Texas and broader parts of eastern Oklahoma at
    late morning. Additional increasingly surface-based development
    seems probable on this near-frontal zone and associated moist axis
    and thermal gradient that extends east-northeastward to the Mid-South/ArkLaMiss. This may include supercells as well as the
    possibility of an upscale-growing complex. Other initially elevated
    severe storms are expected to continue and increase today from
    northeast Oklahoma across the Ozarks toward parts of the
    Mid-South/Mississippi Valley. Large hail is the initial risk, but a surface-based storm risk could develop pending boundary layer
    warming.

    Broadly speaking outside on ongoing storms, a strongly unstable
    airmass exists across the southern Plains to the ArkLaTex, along and
    near a slowly retreating/northward-returning warm front. This is
    beneath relatively strong winds aloft, particularly in
    mid/high-levels based on morning upper-air data. Additional intense surface-based convective development is forecast near the triple
    point in north-central Texas towards the ArkLaTex this afternoon,
    where extreme instability (4000+ J/kg MLCAPE) and very strong
    deep-layer shear (50-60+ kt) will support the potential for multiple
    intense supercells. Very large to giant hail (2-4+ inches) may occur
    with the strongest supercells given the overall very favorable
    environment and presence of steep mid-level lapse rates. Some
    tornado threat may also exist with these supercells, even though
    low-level shear is not forecast to be overly strong.

    Additional severe storms are expected as far east as Mississippi and
    Alabama today -- see Mesoscale Discussion 594 for short-term
    details. An additional secondary round of upscale-growing storms
    with increasing damaging wind potential could also move into this
    same region late today, or more so tonight.

    $$

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  • From COD Weather Processor@1:2320/107 to wx-storm@lists.illinois.edu on Wednesday, April 29, 2026 01:03:31
    ACUS01 KWNS 290103
    SWODY1
    SPC AC 290101

    Day 1 Convective Outlook
    NWS Storm Prediction Center Norman OK
    0801 PM CDT Tue Apr 28 2026

    Valid 290100Z - 291200Z

    ...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS ACROSS PORTIONS
    OF NORTHEAST TEXAS...ARKANSAS...NORTHERN LOUISIANA...AND
    MISSISSIPPI...

    ...SUMMARY...
    Severe thunderstorms will continue this evening across parts of the
    ArkLaTex into the Lower Mississippi Valley. Very large hail (2+
    inches), swaths of severe/damaging winds, and a few tornadoes are
    all possible.

    ...01z Update...

    Scattered severe thunderstorms are ongoing across northeast TX into
    AR, MS and vicinity. A mix of storms modes, including supercells and
    bowing segments will persist into the nighttime hours. Areas of
    large to very large hail (2+ inches with strongest cells), a few
    tornadoes (a couple could be strong), and damaging wind gusts remain
    possible over the next several hours.

    The main outlook changes were to reduce severe probabilities across
    areas where storm potential has diminished, particularly for the
    Lever 4 of 5 (Moderate) risk area in TX where storms have moved
    southeast out of that area and redevelopment to the north appears
    unlikely.

    ..Leitman.. 04/29/2026

    $$

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  • From COD Weather Processor@1:2320/107 to wx-storm@lists.illinois.edu on Wednesday, April 29, 2026 04:55:05
    ACUS01 KWNS 290455
    SWODY1
    SPC AC 290453

    Day 1 Convective Outlook
    NWS Storm Prediction Center Norman OK
    1153 PM CDT Tue Apr 28 2026

    Valid 291200Z - 301200Z

    ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS PORTIONS
    OF TEXAS AND THE GULF COAST STATES INTO SOUTHERN GEORGIA AND SOUTH CAROLINAS...AND ACROSS THE CENTRAL APPALACHIANS/SOUTHERN
    MID-ATLANTIC...

    ...SUMMARY...
    Widely scattered strong to severe storms may impact a corridor from
    south of the Texas Big Bend into the Gulf coast states and southern Georgia/South Carolina Wednesday afternoon into evening. Additional
    strong storms are expected across the central Appalachians and
    southern Mid-Atlantic.

    ...Synopsis...

    An upper trough will pivot across the Great Lakes and Midwest today.
    Within southern stream flow, a weak shortwave impulse will migrate
    through westerly flow aloft from Texas to the GA/SC coast. This will
    result in enhanced westerly flow across the southern U.S. and the
    Midwest to the Mid-Atlantic. At the surface, a cold front is
    forecast to extend from northern IN southwestward into central TX
    this morning. This front will develop southward across TX and
    southeastward across the Lower MS Valley and Southeast through the
    period. The northern extent of the front will shift east across the
    Midwest to the Mid-Atlantic. This surface boundary will be a focus
    for strong to severe thunderstorm development during the
    afternoon/evening.

    ...TX to GA/SC Coast...

    A moist airmass will be in place ahead of the surface front,
    particularly across TX where dewpoints in the 70s are common.
    Heating into the 80s and 90 of this very moist airmass will result
    in a corridor of moderate to strong MLCAPE. The surface boundary
    will be the main forcing mechanism for convection across TX and
    storm coverage may remain isolated. Further east into the Lower MS Valley/Southeast, a shortwave impulse will provide modest forcing
    for ascent in addition to the southeast sagging cold front.

    Isolated supercells across central TX will pose a risk for large
    hail, with some potential for 2+ inch hail. Uncertainty concerning
    storm coverage and capping across TX precludes an upgrade to Sight
    risk at this time. Additional storms are expected to develop closer
    to the Sabine Valley and Lower MS Valley this afternoon. Initial
    thunderstorm clusters may congeal into one or more linear segment
    and move across MS/AL/GA during the late afternoon into evening
    hours. Hail and strong wind gusts will be possible with this
    activity.

    ...Central Appalachians/Mid-Atlantic vicinity...

    An upper shortwave trough emanating from the Great Lakes/Midwest
    upper trough will overspread the region during the afternoon/evening
    in tandem with the eastward advancing cold front. Modest boundary
    layer moisture is forecast across the region, with dewpoints
    generally in the 50s to near 60 F. Modest heating will result in
    weak destabilization (generally 500-750 J/kg or less). Despite weak instability, supercell wind profiles are evident in forecast
    soundings. This should aid in at least transient organization of
    stronger updrafts with a wind and hail risk. While instability and
    moisture will be marginal, 0-1 SRH will approach 150 m2/s2 in
    proximity to a weak surface low and a brief tornado could also
    occur.

    ..Leitman/Moore.. 04/29/2026

    $$

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  • From COD Weather Processor@1:2320/107 to wx-storm@lists.illinois.edu on Wednesday, April 29, 2026 12:07:38
    ACUS01 KWNS 291207
    SWODY1
    SPC AC 291205

    Day 1 Convective Outlook
    NWS Storm Prediction Center Norman OK
    0705 AM CDT Wed Apr 29 2026

    Valid 291300Z - 301200Z

    ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FROM PARTS OF
    TEXAS INTO THE LOWER MISSISSIPPI VALLEY AND THE CENTRAL GULF
    COAST...

    ...SUMMARY...
    Strong to severe thunderstorms should impact a corridor from parts
    of Texas to the Gulf Coast states today. Scattered damaging winds
    and large hail are the main threats, with isolated very large hail
    possible across portions of Texas.

    ...Texas into the Lower Mississippi Valley/Southeast...
    A broad zone of enhanced westerly mid-level flow will persist today
    over much of the southern Plains into the lower MS Valley and
    Southeast. Multiple weak embedded perturbations aloft moving from
    northern Mexico across the southern Plains should encourage isolated
    to scattered thunderstorms to develop through the day along/near a
    surface front draped from west-central TX to southern AR. A rather
    moist low-level airmass remains in place along/south of this
    boundary, with surface dewpoints generally in the low to mid 70s.
    Steep mid-level lapse rates atop this moisture are supporting up to
    2000-4000 J/kg of MUCAPE across TX, with somewhat lesser values into
    the lower MS Valley.

    Current expectations are for a gradual increase in convective
    coverage and intensity this morning through the afternoon as the
    weak mid-level shortwave impulses develop eastward across the warm
    sector, with multiple zones of initiation possible along/near the
    front. Regardless of where thunderstorms form, the moderate to very
    strong instability and elongated/nearly straight hodographs at
    mid/upper levels should support a threat for large hail with any
    persistent supercells. This hail threat should be greater across TX
    (with isolated 2+ inch diameter hailstones possible here), but
    isolated severe hail may occur as far east as the central/southern
    AL vicinity. A tendency for thunderstorms to cluster and pose a
    greater damaging wind threat may focus across parts of the lower MS
    Valley, generally along/southwest of ongoing convection occurring
    this morning in east-central MS to northern/central AL. Given
    increased confidence in convection initiating and being sustained, a
    Slight Risk for the hail/wind threat has been introduced from parts
    of TX to southern AL with this update.

    ...Mid-Atlantic/North Carolina...
    Within large-scale upper troughing over the Great Lakes/Midwest, an
    embedded mid-level shortwave trough will move northeastward across
    the Mid-Atlantic this afternoon/evening in tandem with an
    eastward-moving surface cold front. Only modest boundary layer
    moisture is present across the region, with surface dewpoints
    generally in the 50s. Filtered diurnal heating will result in
    generally 250-750 J/kg MLCAPE (locally greater possible in NC).
    Despite this weak instability, strong deep-layer shear should aid in
    transient organization of the more robust cores that can form. An
    isolated threat for hail and damaging winds remains apparent. 0-1 km
    SRH around 100-150 m2/s2 in proximity to a weak surface low could
    also support a brief tornado.

    ..Gleason/Jewell.. 04/29/2026

    $$

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  • From COD Weather Processor@1:2320/107 to wx-storm@lists.illinois.edu on Wednesday, April 29, 2026 15:51:40
    ACUS01 KWNS 291551
    SWODY1
    SPC AC 291549

    Day 1 Convective Outlook
    NWS Storm Prediction Center Norman OK
    1049 AM CDT Wed Apr 29 2026

    Valid 291630Z - 301200Z

    ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FROM PARTS OF
    TEXAS INTO THE LOWER MISSISSIPPI VALLEY AND THE CENTRAL GULF
    COAST...

    ...SUMMARY...
    Strong to severe thunderstorms should impact a corridor from parts
    of Texas to the Gulf Coast states today. Scattered large to very
    large hail and damaging winds are the primary risks with the
    stronger storms.

    ...Texas into the Lower Mississippi Valley/Southeast...
    Satellite imagery late this morning indicates high momentum
    quasi-zonal flow from TX eastward across the central Gulf Coast. An
    upstream perturbation over Chihuahua is forecast to move quickly
    east today reaching central TX late this afternoon. Isolated to
    scattered thunderstorms are forecast to increase in
    coverage/intensity mainly along/near a surface front draped from
    west-central TX to southern AR. A moisture-rich airmass featuring
    lower 70s deg F surface dewpoints south of the front, coupled with a
    plume of 8 deg C/km 700-500 mb lapse rates and some diurnal heating,
    will contribute to 2000-4000 J/kg of MLCAPE decreasing with east
    extent.

    A few initial thunderstorms clusters north of the surface front over
    TX are expected to gradually intensify through early afternoon. The
    moderate to very unstable airmass will combine with elongated/nearly
    straight hodographs to support supercell development with the
    stronger updrafts and an associated risk for large to very large
    hail (1 to 3 inches in diameter). Have extended the 15-percent hail
    and CIG1 hail delineation farther east into northeast TX and western
    LA. For short-term forecast details, please refer to MCD #615.
    Eventually upscale growth into one or more clusters is expected to
    evolve across LA into the central Gulf Coast states later this
    afternoon. Damaging gusts and an isolated risk for large hail will
    be the primary hazards with the stronger storms.

    Farther west, isolated to widely scattered intense storm development
    is forecast across the Edwards Plateau this afternoon. This
    activity may eventually focus closer to the Rio Grande later this
    evening with a large to very large hail threat persisting well after
    dark.

    ...Upper OH Valley into the Mid-Atlantic/North Carolina...
    Within large-scale upper troughing over the Great Lakes/Midwest, an
    embedded mid-level shortwave trough will move northeastward across
    the Mid-Atlantic this afternoon/evening in tandem with an
    eastward-moving surface cold front. Only modest boundary layer
    moisture is present across the region, with surface dewpoints
    generally in the 50s. Forecast soundings over western PA show some
    low-level hodograph curvature within a moist environment. Main
    uncertainty across the upper OH Valley is the magnitude of
    destabilization in this area given ongoing scattered showers and
    widespread cloud cover. Nonetheless, a couple of stronger storms
    could yield an isolated risk for wind damage and perhaps a brief
    tornado later this afternoon, especially near/southeast of a weak
    surface low. Farther south, isolated wind/hail will be possible
    with the stronger thunderstorms through the late afternoon/early
    evening.

    ..Smith/Chalmers.. 04/29/2026

    $$

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  • From COD Weather Processor@1:2320/107 to wx-storm@lists.illinois.edu on Wednesday, April 29, 2026 20:02:44
    ACUS01 KWNS 292002
    SWODY1
    SPC AC 292000

    Day 1 Convective Outlook
    NWS Storm Prediction Center Norman OK
    0300 PM CDT Wed Apr 29 2026

    Valid 292000Z - 301200Z

    ...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS FOR PORTIONS OF
    THE EDWARDS PLATEAU INTO SOUTH-CENTRAL TEXAS...

    ...SUMMARY...
    Severe thunderstorms are forecast from parts of Texas to the Gulf
    Coast states today. Scattered large to very large hail and damaging
    winds are the primary risks, with giant hail possible in parts of
    south-central Texas.

    ...20Z Update...
    The primary change with this update was the addition of an Enhanced
    Risk for portions of the Edwards Plateau into south-central TX --
    driven by a CIG2 (intensity level 2/2) hail area. The latest visible
    satellite imagery indicates an agitated boundary-layer cumulus field
    evolving east of Fort Stockton in Crockett County, where attempts at
    isolated convective initiation are underway. Current thinking is
    that continued diurnal heating of a moist air mass (lower 70s
    dewpoints) and upslope flow enhancements will result in isolated to
    widely scattered thunderstorms this afternoon into the evening.
    Current thinking is that storms will track/develop southeastward
    into a corridor of strong to extreme buoyancy -- driven by steep
    midlevel lapse rates (around 8.5 C/km per 12Z DRT sounding) atop the destabilizing PBL. This, combined with a long/straight hodograph
    (60-70 kt of effective shear) and modest forcing for ascent will
    favor intense discrete/splitting supercells. Given the modest
    forcing for ascent, it is unclear how many storms will form in this
    corridor, though any sustained supercells will pose a risk of very
    large to giant hail (3-4+ inches in diameter).

    ..Weinman.. 04/29/2026

    .PREV DISCUSSION... /ISSUED 1049 AM CDT Wed Apr 29 2026/

    ...Texas into the Lower Mississippi Valley/Southeast...
    Satellite imagery late this morning indicates high momentum
    quasi-zonal flow from TX eastward across the central Gulf Coast. An
    upstream perturbation over Chihuahua is forecast to move quickly
    east today reaching central TX late this afternoon. Isolated to
    scattered thunderstorms are forecast to increase in
    coverage/intensity mainly along/near a surface front draped from
    west-central TX to southern AR. A moisture-rich airmass featuring
    lower 70s deg F surface dewpoints south of the front, coupled with a
    plume of 8 deg C/km 700-500 mb lapse rates and some diurnal heating,
    will contribute to 2000-4000 J/kg of MLCAPE decreasing with east
    extent.

    A few initial thunderstorms clusters north of the surface front over
    TX are expected to gradually intensify through early afternoon. The
    moderate to very unstable airmass will combine with elongated/nearly
    straight hodographs to support supercell development with the
    stronger updrafts and an associated risk for large to very large
    hail (1 to 3 inches in diameter). Have extended the 15-percent hail
    and CIG1 hail delineation farther east into northeast TX and western
    LA. For short-term forecast details, please refer to MCD #615.
    Eventually upscale growth into one or more clusters is expected to
    evolve across LA into the central Gulf Coast states later this
    afternoon. Damaging gusts and an isolated risk for large hail will
    be the primary hazards with the stronger storms.

    Farther west, isolated to widely scattered intense storm development
    is forecast across the Edwards Plateau this afternoon. This
    activity may eventually focus closer to the Rio Grande later this
    evening with a large to very large hail threat persisting well after
    dark.

    ...Upper OH Valley into the Mid-Atlantic/North Carolina...
    Within large-scale upper troughing over the Great Lakes/Midwest, an
    embedded mid-level shortwave trough will move northeastward across
    the Mid-Atlantic this afternoon/evening in tandem with an
    eastward-moving surface cold front. Only modest boundary layer
    moisture is present across the region, with surface dewpoints
    generally in the 50s. Forecast soundings over western PA show some
    low-level hodograph curvature within a moist environment. Main
    uncertainty across the upper OH Valley is the magnitude of
    destabilization in this area given ongoing scattered showers and
    widespread cloud cover. Nonetheless, a couple of stronger storms
    could yield an isolated risk for wind damage and perhaps a brief
    tornado later this afternoon, especially near/southeast of a weak
    surface low. Farther south, isolated wind/hail will be possible
    with the stronger thunderstorms through the late afternoon/early
    evening.

    $$

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  • From COD Weather Processor@1:2320/107 to wx-storm@lists.illinois.edu on Thursday, April 30, 2026 00:59:43
    ACUS01 KWNS 300059
    SWODY1
    SPC AC 300057

    Day 1 Convective Outlook
    NWS Storm Prediction Center Norman OK
    0757 PM CDT Wed Apr 29 2026

    Valid 300100Z - 301200Z

    ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF
    THE SOUTHERN PLAINS...LOWER MISSISSIPPI VALLEY AND CENTRAL GULF
    COAST STATES...

    ...SUMMARY...
    Severe thunderstorms are expected this evening from parts of the
    southern Plains eastward into the lower Mississippi Valley and
    central Gulf Coast states. Large hail will be the primary threat in
    the southern Plains. Wind damage and large hail will be possible in
    the parts of the lower Mississippi Valley and central Gulf Coast
    states.

    ...Southern Plains...
    Westerly mid-level flow is in place over much of the southern Plains
    this evening. At the surface, a cold front is located over the Texas
    Hill Country extending westward toward the Big Bend. To the south of
    the front, surface dewpoints in the 70s F are contributing to strong instability over much of south-central and southwest Texas, where
    the RAP has MLCAPE in the 3500 to 5000 J/kg range. To the north of
    the instability max, a robust supercell is ongoing in the western
    Texas Hill Country. Large to very large hail will continue to be
    possible with this supercell as it moves southeastward across
    south-central Texas this evening. Other supercells with potential
    for large to very large hail may develop a further west and
    southwest toward the Rio Grande this evening.

    ...Lower Mississippi Valley/Central Gulf Coast States...
    Current water vapor imagery shows evidence of a subtle shortwave
    trough over east Texas. At the surface, a cold front is located in
    east Texas extending eastward into central Mississippi. To the south
    of the front, surface dewpoints are mostly in the 70s F, which is
    contributing to moderate instability. The axis of instability is
    located from southeast Texas eastward into southern Mississippi.
    Short-term model forecasts suggest that a severe convective cluster
    may develop this evening ahead of the shortwave trough over east
    Texas and move east-southeastward along the instability gradient
    into western Louisiana. If this cluster does materialize, then it
    will likely be associated with a potential for large hail and wind
    damage. Otherwise, convection that develops near the instability
    axis in the central Gulf Coast states this evening will have a
    potential for isolated severe gusts...see MCD 623.

    Further north into parts of northeast Mississippi and north-central
    Alabama, an axis of moderate instability is analyzed by the RAP with
    MLCAPE in the 1500 to 2500 J/kg range. This combined with steep
    mid-level lapse rates will support an isolated severe threat this
    evening. Severe wind gusts and hail will be the primary
    threats...see MCD 625.

    ..Broyles.. 04/30/2026

    $$

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  • From COD Weather Processor@1:2320/107 to wx-storm@lists.illinois.edu on Thursday, April 30, 2026 05:34:46
    ACUS01 KWNS 300534
    SWODY1
    SPC AC 300533

    Day 1 Convective Outlook
    NWS Storm Prediction Center Norman OK
    1233 AM CDT Thu Apr 30 2026

    Valid 301200Z - 011200Z

    ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF
    SOUTHWEST AND SOUTH-CENTRAL TEXAS...

    ...SUMMARY...
    Thunderstorms with isolated large hail will be possible this evening
    into tonight across parts of southwest and south-central Texas.

    ...Southwest and South-central Texas...
    At mid-levels, a low will move across northern Mexico this afternoon
    into tonight, as a 60 to 70 knot mid-level jet ejects eastward
    across the southern Plains. In response, large-scale ascent will
    increase over parts of southwest Texas this evening, supporting
    scattered thunderstorm development. Thunderstorm coverage will
    increase overnight as a cluster of convection moves eastward into
    south-central Texas. These storms will be located to the north of a quasi-stationary front, and will be elevated in nature. Late evening
    forecast soundings in southwest Texas have steep 700-500 mb lapse
    rates (exceeding 7.5 C/km), with effective shear in the 50 to 60
    knot range. This environment will likely support an isolated large
    hail threat, mainly if a supercell can develop.

    ..Broyles/Moore.. 04/30/2026

    $$

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  • From COD Weather Processor@1:2320/107 to wx-storm@lists.illinois.edu on Thursday, April 30, 2026 12:48:14
    ACUS01 KWNS 301248
    SWODY1
    SPC AC 301246

    Day 1 Convective Outlook
    NWS Storm Prediction Center Norman OK
    0746 AM CDT Thu Apr 30 2026

    Valid 301300Z - 011200Z

    ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF
    TEXAS AND COASTAL/SOUTHERN LOUISIANA...

    ...SUMMARY...
    Thunderstorms with isolated large hail and gusty winds will be
    possible mainly this evening and tonight across parts of southwest/south-central Texas towards the middle Texas Coast, and
    this afternoon across coastal/southern Louisiana.

    ...Texas...
    Strong westerly mid-flow will be maintained across the southern
    Plains into the Southeast today, as a mid/upper-level low currently
    off the coast of Baja California quickly moves eastward through the
    period. A surface front is currently stalled across parts of south
    TX, and most of the thunderstorms forecast to develop across TX
    through tonight are expected to remain elevated. Ascent preceding
    the shortwave trough should eventually encourage convection to
    develop near the TX Big Bend late this evening, and spread eastward
    towards the middle TX Coast through early Friday morning. Sufficient
    MUCAPE and strong cloud-layer shear will support an isolated threat
    for severe hail with any elevated supercells that can develop.
    Strong to locally damaging winds may also occur as supercells
    encounter greater instability across south-central to coastal TX
    late tonight, even if they remain slightly elevated. Overall
    confidence in coverage of severe convection remains too low to
    include greater severe hail probabilities and a Slight Risk with
    this update.

    ...Coastal/Southern Louisiana...
    A convectively reinforced surface front is draped across
    southern/coastal LA this morning, with thunderstorms ongoing to its
    north. Greater instability will exist to the south of the front
    across coastal LA this afternoon. Thunderstorms that develop/move
    across the front later today could pose some risk for locally
    damaging winds and marginally severe hail given weak to moderate
    instability and strong deep-layer shear.

    ...Coastal South Carolina...
    Thunderstorms capable of producing occasional strong/gusty winds
    should move offshore within the next hour or two. The overall severe
    wind threat appears too limited to include 5% probabilities.

    ..Gleason/Jewell.. 04/30/2026

    $$

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  • From COD Weather Processor@1:2320/107 to wx-storm@lists.illinois.edu on Thursday, April 30, 2026 15:58:45
    ACUS01 KWNS 301558
    SWODY1
    SPC AC 301557

    Day 1 Convective Outlook
    NWS Storm Prediction Center Norman OK
    1057 AM CDT Thu Apr 30 2026

    Valid 301630Z - 011200Z

    ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF
    TEXAS AND COASTAL/SOUTHERN LOUISIANA...

    ...SUMMARY...
    Thunderstorms with isolated large hail and gusty winds will be
    possible mainly this evening and tonight across parts of southwest/south-central Texas towards the middle Texas Coast, and
    this afternoon across coastal/southern Louisiana.

    ...Texas...
    A mid- to upper-level trough west of northern Baja California late
    this morning is forecast to quickly move east reaching Chihuahua and
    southwest TX by daybreak Friday. Strong westerly mid to high-level
    flow will be maintained across the southern tier of states. Surface
    analysis showed a west-east oriented stalled front across south TX
    eastward across coastal LA and into north FL. Widespread cloud
    cover will limit diurnal heating today north of the boundary despite
    a fetch of steeper 700-500 mb lapse rates being maintained across
    northern Mexico and over TX in the vicinity of the Rio Grande. A
    couple of stronger thunderstorms are possible through the early
    afternoon from central into parts of southeast TX (reference MCD
    #627 for short-term details). Farther west, ascent preceding the
    shortwave trough will promote scattered showers and storms
    developing over southwest TX late this evening with additional
    activity (numerous in coverage) forecast to develop/spread east
    towards the middle TX Coast through early Friday morning. Sufficient
    MUCAPE and strong cloud-layer shear will support an isolated threat
    for severe hail with any elevated supercells that can develop.
    Strong to locally severe gusts may also occur as supercells
    encounter greater instability across south-central to coastal TX
    late tonight, even if they remain slightly elevated.

    ...Coastal/Southern Louisiana...
    A convectively reinforced surface front is draped across
    southern/coastal LA this morning, with thunderstorms ongoing to its
    north. Greater instability will exist to the south of the front
    across coastal LA this afternoon. Thunderstorms that develop/move
    across the front later today could pose some risk for locally
    damaging winds and marginally severe hail given weak to moderate
    instability and strong deep-layer shear.

    ..Smith/Chalmers.. 04/30/2026

    $$

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  • From COD Weather Processor@1:2320/107 to wx-storm@lists.illinois.edu on Thursday, April 30, 2026 19:51:47
    ACUS01 KWNS 301951
    SWODY1
    SPC AC 301950

    Day 1 Convective Outlook
    NWS Storm Prediction Center Norman OK
    0250 PM CDT Thu Apr 30 2026

    Valid 302000Z - 011200Z

    ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS SOUTHERN
    PORTIONS OF TEXAS AND LOUISIANA...

    ...SUMMARY...
    Thunderstorms with isolated large hail and gusty winds will be
    possible mainly this evening and tonight across parts of southwest/south-central Texas towards the middle Texas Coast, and
    this afternoon across coastal/southern Louisiana.

    ...20Z Update...
    The previous forecast (see below) remains on track, with only slight
    changes made to ongoing probabilities to account for the latest
    guidance consensus.

    ..Squitieri.. 04/30/2026

    .PREV DISCUSSION... /ISSUED 1057 AM CDT Thu Apr 30 2026/

    ...Texas...
    A mid- to upper-level trough west of northern Baja California late
    this morning is forecast to quickly move east reaching Chihuahua and
    southwest TX by daybreak Friday. Strong westerly mid to high-level
    flow will be maintained across the southern tier of states. Surface
    analysis showed a west-east oriented stalled front across south TX
    eastward across coastal LA and into north FL. Widespread cloud
    cover will limit diurnal heating today north of the boundary despite
    a fetch of steeper 700-500 mb lapse rates being maintained across
    northern Mexico and over TX in the vicinity of the Rio Grande. A
    couple of stronger thunderstorms are possible through the early
    afternoon from central into parts of southeast TX (reference MCD
    #627 for short-term details). Farther west, ascent preceding the
    shortwave trough will promote scattered showers and storms
    developing over southwest TX late this evening with additional
    activity (numerous in coverage) forecast to develop/spread east
    towards the middle TX Coast through early Friday morning. Sufficient
    MUCAPE and strong cloud-layer shear will support an isolated threat
    for severe hail with any elevated supercells that can develop.
    Strong to locally severe gusts may also occur as supercells
    encounter greater instability across south-central to coastal TX
    late tonight, even if they remain slightly elevated.

    ...Coastal/Southern Louisiana...
    A convectively reinforced surface front is draped across
    southern/coastal LA this morning, with thunderstorms ongoing to its
    north. Greater instability will exist to the south of the front
    across coastal LA this afternoon. Thunderstorms that develop/move
    across the front later today could pose some risk for locally
    damaging winds and marginally severe hail given weak to moderate
    instability and strong deep-layer shear.

    $$

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  • From COD Weather Processor@1:2320/107 to wx-storm@lists.illinois.edu on Friday, May 01, 2026 01:02:20
    ACUS01 KWNS 010102
    SWODY1
    SPC AC 010100

    Day 1 Convective Outlook
    NWS Storm Prediction Center Norman OK
    0800 PM CDT Thu Apr 30 2026

    Valid 010100Z - 011200Z

    ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF
    SOUTHWEST TEXAS...

    ...SUMMARY...
    Thunderstorms with large hail and isolated severe wind gusts will be
    possible this evening into tonight across parts of southwest Texas.

    ...Southwest and South-central Texas...
    A mid-level shortwave trough is evident on water vapor imagery over
    far northeastern Mexico. At the surface, a quasi-stationary front is
    located across south Texas, with a post-frontal airmass in place
    over much of southwest and south-central Texas. A strong
    thunderstorm is ongoing to the east of the Sierra Madre Oriental
    mountains in northern Mexico. This storm will move eastward toward
    the Rio Grande and will likely cross the river later this evening.
    Mid evening RAP forecast soundings in the Laredo, Texas vicinity
    have effective shear around 65 knots with 700-500 mb lapse rates
    near 7 C/km. This will support a large hail threat. On the forecast
    sounding, the temperature is nearly isothermal in the lowest 1000
    meters, with CAPE mainly concentrated above 700 mb suggesting that
    any supercell will likely be elevated. The large hail threat could
    continue into the late evening and early overnight period, but the
    area should be confined to a small area in southwest and
    south-central Texas.

    ..Broyles.. 05/01/2026

    $$

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  • From COD Weather Processor@1:2320/107 to wx-storm@lists.illinois.edu on Friday, May 01, 2026 05:50:52
    ACUS01 KWNS 010550
    SWODY1
    SPC AC 010548

    Day 1 Convective Outlook
    NWS Storm Prediction Center Norman OK
    1248 AM CDT Fri May 01 2026

    Valid 011200Z - 021200Z

    ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF SOUTH-CENTRL AND SOUTHWEST TEXAS...AND IN THE CENTRAL GULF COAST...

    ...SUMMARY...
    Thunderstorms with isolated severe wind gusts and hail will be
    possible today across parts of south-central and southeast Texas,
    and this evening into tonight along the central Gulf Coast.

    ...South-central and Southeast Texas...
    At mid-levels, a shortwave trough will move eastward across northern
    Mexico today, as a jet streak ahead of the trough translates
    eastward into the western Gulf Coast states. At the surface, a
    quasi-stationary front will remain over south Texas extending
    eastward to the middle Texas Coast. Large-scale ascent ahead of the
    trough will support scattered thunderstorm development across the
    post-frontal airmass in the southern Texas Hill Country. Storms will
    develop and move eastward across the middle and upper Texas Coastal
    Plain during the morning and afternoon. Moderate instability is
    expected to be in place near the front today, aided by surface
    dewpoints in the lower to mid 70s F. In addition, the mid-level jet
    will create strong deep-layer shear favorable for a few rotating
    storms capable of large hail and isolated severe wind gusts. This
    potential will be greatest along the instability gradient across the
    middle Texas Coast to the north of Corpus Christi. The severe threat
    is expected to gradually end from west to east during the late
    afternoon as the stronger instability shifts offshore into the Gulf.

    ...Central Gulf Coast...
    A mid-level shortwave trough will move through the western Gulf
    Coast states this evening, as the entrance region of a mid-level jet overspreads the region. Ahead of the trough, large-scale ascent will
    support scattered thunderstorm development from this afternoon into
    tonight. Surface dewpoints in the mid 60 F in the immediate coastal
    areas of southeast Louisiana, far southern Mississippi and far
    southern Alabama will contribute to sufficient instability for
    isolated severe storms. A few of the stronger storms could produce
    strong wind gusts and hail. The severe threat could increase late
    this evening into the overnight, especially if a convective cold
    pool can organize in the coastal areas. If this conditional scenario materializes, then wind damage would become the primary threat.

    ..Broyles/Lyons.. 05/01/2026

    $$

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  • From COD Weather Processor@1:2320/107 to wx-storm@lists.illinois.edu on Friday, May 01, 2026 12:33:24
    ACUS01 KWNS 011233
    SWODY1
    SPC AC 011231

    Day 1 Convective Outlook
    NWS Storm Prediction Center Norman OK
    0731 AM CDT Fri May 01 2026

    Valid 011300Z - 021200Z

    ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS FROM THE TEXAS
    HILL COUNTRY INTO THE UPPER TEXAS COAST...AND ACROSS THE CENTRAL
    GULF COAST INTO THE FLORIDA PANHANDLE...

    ...SUMMARY...
    Thunderstorms with isolated severe wind gusts and hail will be
    possible today across parts of south-central and southeast Texas,
    and this evening into tonight along the central Gulf Coast.

    ...Synopsis and Discussion...
    Early morning satellite imagery shows several shortwave troughs,
    including one within the southern stream over northern Mexico and
    another moving into Ohio Valley within the base of a large cyclone
    centered over the northern Ontario/Quebec border vicinity. Recent
    surface analysis places a weak front from Deep South Texas
    northeastward through the western Gulf and central Plaquemines
    Parish, continuing through the north-central Gulf and across
    northern Florida. Numerous showers and thunderstorms are currently
    ongoing north of the front and downstream of the northern Mexico
    shortwave from the Texas Hill County eastward to the Upper Texas
    Coast.

    Thermodynamic conditions across these region are expected to remain
    largely unchanged throughout much of the day, with modest elevated
    instability persisting amid the moist southwesterly mid-level flow.
    Some modest increase in the mid-level flow is anticipated as the
    shortwave trough continues eastward through TX and into the Lower
    Mississippi Valley. An attendant increase in large-scale ascent is
    expected as well. Resulting increase in the deep-layer shear could
    result in slightly more organized storm structures and greater
    overall storm intensity this afternoon despite numerous preceding
    showers and thunderstorms, and little change in the overall
    thermodynamics. Large hail and damaging gusts are the primary risks
    with the strongest storms.

    A surface low is expected to develop ahead of the shortwave trough
    over the western Gulf, before then tracking quickly northeastward as
    the shortwave continues eastward. This low will likely be just off
    the Deep South Texas Coast by 00Z Saturday, and off of southern
    Plaquemines Parish by 06Z. Elevated thunderstorms are expected
    across the Lower MS Valley amid a combination of warm-air advection
    and large-scale ascent ahead of the shortwave. The strongest storms
    may be capable of producing small hail. The surface low may also
    track far enough north for the warm sector to advect into the
    near-coastal regions of southeast Louisiana, far southern
    Mississippi, southern Alabama and the western/central Florida
    Panhandle. If this occurs, surface-based storms could develop,
    enhancing the potential for damaging gusts as well as introducing a low-probability tornado risk.

    ..Mosier/Dean.. 05/01/2026

    $$

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  • From COD Weather Processor@1:2320/107 to wx-storm@lists.illinois.edu on Friday, May 01, 2026 16:26:24
    ACUS01 KWNS 011626
    SWODY1
    SPC AC 011624

    Day 1 Convective Outlook
    NWS Storm Prediction Center Norman OK
    1124 AM CDT Fri May 01 2026

    Valid 011630Z - 021200Z

    ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS FROM
    SOUTH-CENTRAL TEXAS TO THE UPPER COAST OF TEXAS...AND THE CENTRAL
    GULF COAST INTO THE FLORIDA PANHANDLE...

    ...SUMMARY...
    Thunderstorms with isolated severe wind gusts and hail will be
    possible today across parts of south-central and southeast Texas,
    and this evening into tonight along the central Gulf Coast.

    ...Synopsis...
    Late morning water-vapor imagery shows a potent mid-level shortwave
    trough moving east across Far West TX and Chihuahua. This upper
    feature will move quickly east and weaken while moving into
    increasingly confluent flow through the base of a larger-scale
    eastern U.S. trough. As a weak cyclone develops east along a
    west-east draped front from south TX northeastward to the mouth of
    the MS River, strengthening low to mid-level flow associated with
    warm advection will overspread the northern Gulf of America into the
    FL Panhandle tonight.

    Strong to locally severe thunderstorm clusters have episodically
    developed and moved east across south-central TX this morning
    immediately downstream of the upper disturbance. Localized
    hail/wind may accompany the stronger storms through the mid-late
    afternoon. A shallow post-frontal stable layer near the surface and
    weak instability lended confidence in removing low tornado
    probabilities over TX this outlook update. See MCD #632 regarding
    short-term details.

    Farther east, little in the way of destabilization is currently
    depicted by the latest model guidance to the north of the front,
    specifically from near Lake Pontchartrain eastward over the near
    shore waters to the south of Mobile Bay and the western FL
    Panhandle. North of the boundary, a low risk for large hail will be
    maintained as a couple of stronger elevated storms intensify later
    this evening into the overnight and traverse eastward in tandem with
    increasing large-scale ascent/strengthening flow fields. Near and
    immediately south of the front, have focused the tornado and wind
    probabilities this outlook update to the proximity of surface-based
    inflow parcels potentially being realized by organized storm modes.

    ..Smith/Chalmers.. 05/01/2026

    $$

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  • From COD Weather Processor@1:2320/107 to wx-storm@lists.illinois.edu on Friday, May 01, 2026 19:51:26
    ACUS01 KWNS 011951
    SWODY1
    SPC AC 011949

    Day 1 Convective Outlook
    NWS Storm Prediction Center Norman OK
    0249 PM CDT Fri May 01 2026

    Valid 012000Z - 021200Z

    ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ALONG PORTIONS
    OF THE GULF COAST...

    ...SUMMARY...
    Thunderstorms with isolated severe wind gusts and hail will be
    possible today across parts of southeast Texas, and this evening
    into tonight along the central Gulf Coast.

    ...20Z Update...
    The previous forecast (see below) remains on track. Some trimming
    was done to thunder/severe probabilities in western into southern
    Texas, with 5 percent hail probabilities added in southern LA, to
    account for the latest storm trends and near-term guidance
    consensus.

    ..Squitieri.. 05/01/2026

    .PREV DISCUSSION... /ISSUED 1124 AM CDT Fri May 01 2026/

    ...Synopsis...
    Late morning water-vapor imagery shows a potent mid-level shortwave
    trough moving east across Far West TX and Chihuahua. This upper
    feature will move quickly east and weaken while moving into
    increasingly confluent flow through the base of a larger-scale
    eastern U.S. trough. As a weak cyclone develops east along a
    west-east draped front from south TX northeastward to the mouth of
    the MS River, strengthening low to mid-level flow associated with
    warm advection will overspread the northern Gulf of America into the
    FL Panhandle tonight.

    Strong to locally severe thunderstorm clusters have episodically
    developed and moved east across south-central TX this morning
    immediately downstream of the upper disturbance. Localized
    hail/wind may accompany the stronger storms through the mid-late
    afternoon. A shallow post-frontal stable layer near the surface and
    weak instability lended confidence in removing low tornado
    probabilities over TX this outlook update. See MCD #632 regarding
    short-term details.

    Farther east, little in the way of destabilization is currently
    depicted by the latest model guidance to the north of the front,
    specifically from near Lake Pontchartrain eastward over the near
    shore waters to the south of Mobile Bay and the western FL
    Panhandle. North of the boundary, a low risk for large hail will be
    maintained as a couple of stronger elevated storms intensify later
    this evening into the overnight and traverse eastward in tandem with
    increasing large-scale ascent/strengthening flow fields. Near and
    immediately south of the front, have focused the tornado and wind
    probabilities this outlook update to the proximity of surface-based
    inflow parcels potentially being realized by organized storm modes.

    $$

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  • From COD Weather Processor@1:2320/107 to wx-storm@lists.illinois.edu on Saturday, May 02, 2026 00:24:26
    ACUS01 KWNS 020024
    SWODY1
    SPC AC 020023

    Day 1 Convective Outlook
    NWS Storm Prediction Center Norman OK
    0723 PM CDT Fri May 01 2026

    Valid 020100Z - 021200Z

    ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS PORTIONS
    OF THE CENTRAL GULF COAST...

    ...SUMMARY...
    Thunderstorms with isolated severe wind gusts will be possible this
    evening into tonight along the central Gulf Coast.

    ...Discussion...
    Thunderstorm activity will continue across portions of the central
    Gulf Coast this evening. While the more favorably unstable air mass
    remains mostly offshore, occasional strong cells/clusters may track
    inland with potential for damaging winds as large scale ascent
    increasing through the evening/overnight period. Closer to the front
    offshore, a few transient supercells and a tornado may be possible.
    Overall, the threat inland remains isolated and a Marginal risk was
    maintained this evening to account for this potential.

    ..Thornton.. 05/02/2026

    $$

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  • From COD Weather Processor@1:2320/107 to wx-storm@lists.illinois.edu on Saturday, May 02, 2026 05:28:59
    ACUS01 KWNS 020528
    SWODY1
    SPC AC 020527

    Day 1 Convective Outlook
    NWS Storm Prediction Center Norman OK
    1227 AM CDT Sat May 02 2026

    Valid 021200Z - 031200Z

    ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS SOUTHERN
    GEORGIA...EASTERN FLORIDA PANHANDLE INTO NORTH AND CENTRAL
    FLORIDA...

    ...SUMMARY...
    Strong to severe storms are possible across southern Georgia into northern/central Florida this morning into the early evening.

    ...Synopsis...
    An upper-level trough will bring enhanced west-southwesterly flow
    aloft across the southeast into the Gulf Coast Saturday. A cold
    front extending across the northern Florida Peninsula into the Gulf
    will shift south and east through the afternoon, as a focus of
    severe thunderstorm development. Thunderstorm activity is expected
    at the beginning of the period, some of which perhaps may be strong.

    ...Southern Georgia into central Florida...
    Thunderstorm activity will likely be ongoing at the start of the
    period early Saturday morning across the Gulf into the Florida
    Panhandle and southern Georgia. A few stronger transient supercells
    will be possible, mainly offshore south of the Florida coast where
    better instability will overlap increasing upper-level flow.

    Thunderstorm activity will increase in coverage inland and across
    southern Georgia into the eastern Florida Panhandle and northern
    Florida Peninsula through the morning into the afternoon. Moderately
    unstable and strongly sheared profiles across the region will
    support potential for damaging winds and large hail, especially with
    embedded supercells. Given storm motions parallel to the southwest
    to northeast oriented cold front, supercells will likely struggle to
    remain discrete. As the low-level jet becomes displaced to the north
    by late morning into the afternoon, mode may becoming increasingly
    more clustered/linear. This may reduce the hail potential through
    time.

    Before the low-level jet shifts northward, risk for a tornado will
    be possible across the northern peninsula near the front. There is a
    narrow zone in north Florida where marginally stronger low-level
    shear and boundary-layer destabilization may favorably align
    mid/late morning for a higher tornado risk. Overall, confidence is
    low in favorable overlap, with potential largely occurring outside
    of peak daytime heating and with the low-level jet beginning to
    shift northward. As mentioned, there is also concern about storm
    motions and lack of more discrete supercells. This leads to too much uncertainty in introducing higher tornado probabilities at this
    time.

    A Slight Risk was maintained across southern Georgia into the
    eastern Florida Panhandle and northern/central Florida for the main
    threats of damaging wind and large hail.

    ..Thornton/Lyons.. 05/02/2026

    $$

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  • From COD Weather Processor@1:2320/107 to wx-storm@lists.illinois.edu on Saturday, May 02, 2026 12:18:01
    ACUS01 KWNS 021217
    SWODY1
    SPC AC 021216

    Day 1 Convective Outlook
    NWS Storm Prediction Center Norman OK
    0716 AM CDT Sat May 02 2026

    Valid 021300Z - 031200Z

    ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS THE
    NORTHERN/CENTRAL FLORIDA PENINSULA AND FAR SOUTHEAST GEORGIA...

    ...SUMMARY...
    Strong to severe storms are possible across southern Georgia into northern/central Florida this morning into the early evening.

    ...Northern/Central Florida into far southeast Georgia...
    Regional radar imagery shows a broad area of precipitation extending
    from the northeast Gulf northeastward through the Carolinas.
    Thunderstorms are ongoing within the southern portion of this
    precipitation shield, from the northeast Gulf into central and
    eastern FL Panhandle. This region is just downstream of a
    low-amplitude shortwave trough and in the vicinity of an associated
    surface low. Stronger ascent and modest buoyancy is favoring deeper
    updrafts across this region compared to areas farther north.

    Updrafts in this area have been fairly transient overnight and for
    the first few hours this morning, likely resulting from a
    combination of modest buoyancy, boundary-parallel deep-layer shear,
    and elevated storm structures. Some improvement in storm
    organization appears possible over the next few hours as the
    low-level flow strengthens and convergence near the surface low
    augments large-scale ascent. This better storm organization should
    result in stronger updrafts and longer overall updraft persistence,
    with an attendant increase in the risk for damaging gusts.
    Additionally, there is enough low-level curvature to support a brief
    tornado or two if surface-based storms can be realized.
    Surface-based storms appear most probable over the northwest FL
    vicinity and a small 5% tornado probability was delineated to
    highlight this potential.

    This area was also addressed in recently issued MCD #0635.

    ..Mosier/Dean.. 05/02/2026

    $$

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  • From COD Weather Processor@1:2320/107 to wx-storm@lists.illinois.edu on Saturday, May 02, 2026 16:31:38
    ACUS01 KWNS 021631
    SWODY1
    SPC AC 021629

    Day 1 Convective Outlook
    NWS Storm Prediction Center Norman OK
    1129 AM CDT Sat May 02 2026

    Valid 021630Z - 031200Z

    ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS THE
    NORTHERN/CENTRAL FLORIDA PENINSULA...

    ...SUMMARY...
    Severe thunderstorms are possible across the northern and central
    Florida Peninsula through early evening.

    ...Northern/Central Florida...
    At midday, a line of gradually intensifying storms extends northeast-southwestward across the northern Florida Peninsula to the
    nearby Gulf, with additional offshore development occurring about as
    far south as the Tampa Bay vicinity. This line will continue to move
    inland and further intensify as the boundary layer warms inland in
    conjunction with near-70F surface dewpoints. Some additional
    more-discrete development may occur ahead of the line, potentially
    focusing along the east coast. Damaging winds are the most probable
    severe hazard as low/mid-level winds further strengthen, albeit with
    a tendency for low-level veering over time. Even so, a tornado or
    two could occur aside from damaging winds.

    ...Western Oregon/northern California...
    Influenced by upper-jet exit region and the prominent trough off the
    coast of Oregon/California, a few stronger storms may develop across
    the region late this afternoon through early evening. While gusty
    winds and/or small hail could occur, the potential for organized
    severe storms should remain low given the modest instability and
    weak deep-layer shear.

    ..Guyer/Chalmers.. 05/02/2026

    $$

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  • From COD Weather Processor@1:2320/107 to wx-storm@lists.illinois.edu on Saturday, May 02, 2026 19:55:35
    ACUS01 KWNS 021955
    SWODY1
    SPC AC 021953

    Day 1 Convective Outlook
    NWS Storm Prediction Center Norman OK
    0253 PM CDT Sat May 02 2026

    Valid 022000Z - 031200Z

    ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS FOR PORTIONS OF
    THE CENTRAL FLORIDA PENINSULA...

    ...SUMMARY...
    A few severe thunderstorms remain possible across the northern and
    central Florida Peninsula through early evening.

    ...20Z Update...
    The primary change to the outlook was to trim thunder and severe
    probabilities where storms have contributed to boundary layer
    stabilization, particularly over the central FL Peninsula. Category
    1/Marginal risk probabilities have been maintained ahead of a broken
    band of storms. Here, an adequate overlap of buoyancy and deep-layer
    shear remains to support multicells and transient supercells capable
    of producing an instance or two of hail, gusty winds, or a brief
    tornado.

    ..Squitieri.. 05/02/2026

    .PREV DISCUSSION... /ISSUED 1129 AM CDT Sat May 02 2026/

    ...Northern/Central Florida...
    At midday, a line of gradually intensifying storms extends northeast-southwestward across the northern Florida Peninsula to the
    nearby Gulf, with additional offshore development occurring about as
    far south as the Tampa Bay vicinity. This line will continue to move
    inland and further intensify as the boundary layer warms inland in
    conjunction with near-70F surface dewpoints. Some additional
    more-discrete development may occur ahead of the line, potentially
    focusing along the east coast. Damaging winds are the most probable
    severe hazard as low/mid-level winds further strengthen, albeit with
    a tendency for low-level veering over time. Even so, a tornado or
    two could occur aside from damaging winds.

    ...Western Oregon/northern California...
    Influenced by upper-jet exit region and the prominent trough off the
    coast of Oregon/California, a few stronger storms may develop across
    the region late this afternoon through early evening. While gusty
    winds and/or small hail could occur, the potential for organized
    severe storms should remain low given the modest instability and
    weak deep-layer shear.

    $$

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  • From COD Weather Processor@1:2320/107 to wx-storm@lists.illinois.edu on Sunday, May 03, 2026 00:27:05
    ACUS01 KWNS 030026
    SWODY1
    SPC AC 030025

    Day 1 Convective Outlook
    NWS Storm Prediction Center Norman OK
    0725 PM CDT Sat May 02 2026

    Valid 030100Z - 031200Z

    ...NO SEVERE THUNDERSTORM AREAS FORECAST...

    ...SUMMARY...
    No severe thunderstorms are expected through the rest of the period.

    ...Synopsis...
    The Marginal Risk across the Florida Peninsula has been removed with
    this outlook. Scattered thunderstorms will continue across the
    region but are expected to remain sub-severe with the loss of
    daytime heating and thunderstorm activity becoming mainly
    post-frontal.

    Scattered thunderstorms will be possible this evening across
    portions of the Southwest into Great Basin and across the Northern
    Rockies. With weakly sheared profiles and marginal instability, no
    severe storms are forecast.

    ..Thornton.. 05/03/2026

    $$

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  • From COD Weather Processor@1:2320/107 to wx-storm@lists.illinois.edu on Sunday, May 03, 2026 05:38:05
    ACUS01 KWNS 030538
    SWODY1
    SPC AC 030536

    Day 1 Convective Outlook
    NWS Storm Prediction Center Norman OK
    1236 AM CDT Sun May 03 2026

    Valid 031200Z - 041200Z

    ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS FOR PARTS OF NORTHERN/CENTRAL MISSOURI INTO CENTRAL ILLINOIS...

    ...SUMMARY...
    A few strong thunderstorms are possible across parts of
    northern/central Missouri and central Illinois on Sunday.

    ...Synopsis...
    A short-wave trough with a belt of enhanced northwesterly flow
    within the broader eastern US trough will overspread the Missouri
    Valley through this evening. A weak cold front will extend across
    portions of the central Plains into the Missouri Valley. This
    boundary will be the focus for potential isolated thunderstorm
    development as the short-wave moves in across the region by the
    evening.

    ...Northern/central Missouri into central Illinois...
    Moisture quality continues to be a question within the Marginal Risk
    area as previously stated in prior outlooks. Surface observations
    show 50s dew points have made it as far north as the Red River in
    southern Oklahoma as of late Saturday evening. There remains some
    question just how far north (or deep) this moisture will be by late
    afternoon across Missouri/Illinois. Most 00z guidance suggests that
    50 F dew points will steadily spread into Missouri through the day
    today. However, afternoon sounding profiles suggest this moisture to
    be thin and potentially subject to mixing. Through the afternoon,
    weak convergence along the front and a mid-level capping inversion
    will likely prohibit convective development. As the short-wave
    ascent arrives in the evening, 00z HREF guidance suggest that at
    least isolated thunderstorms may develop (as seen in ensemble paint
    balls >40z dBZ and in calibrated thunder chances around 40-50%).
    Temperatures aloft will be rather cold (around -20 C at 500 mb).
    Even upper 40s F dewpoints will result in around 1000 to perhaps
    1500 J/kg MLCAPE by late afternoon/early evening. Given steepening
    lapse rate profiles and cold temperatures aloft, potential for a few
    instances of severe hail and strong to severe winds will be
    possible.

    ...Northern California/southwest Oregon...
    Convection is possible during the afternoon as mid-level
    temperatures cool in close proximity to the upper low off the coast.
    Filtered surface heating could allow for a few stronger storms to
    develop. Small hail and gusty winds are possible. Anvil-level flow
    will be quite weak which will likely lead to storms that are only
    strong briefly. The overall severe potential appears low.

    ..Thornton/Lyons.. 05/03/2026

    $$

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  • From COD Weather Processor@1:2320/107 to wx-storm@lists.illinois.edu on Sunday, May 03, 2026 12:44:39
    ACUS01 KWNS 031244
    SWODY1
    SPC AC 031242

    Day 1 Convective Outlook
    NWS Storm Prediction Center Norman OK
    0742 AM CDT Sun May 03 2026

    Valid 031300Z - 041200Z

    ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS FOR PARTS OF NORTHERN/CENTRAL MISSOURI AND CENTRAL ILLINOIS ON SUNDAY....

    ...SUMMARY...
    A few strong thunderstorms are possible across parts of
    northern/central Missouri and central Illinois today.

    ...Synopsis...
    Early-morning satellite imagery shows broadly cyclonic flow across
    much of the CONUS. The only exceptions are along the West Coast,
    which is being influenced by an upper low just off the CA coast, and
    the Southwest States, where minor shortwave ridging exists. A
    low-amplitude shortwave trough is currently moving
    southward/southeastward within this broadly cyclonic flow through
    the Upper Midwest and northern Plains, with continued southeastward
    progression expected throughout the period.

    Recent surface analysis reveals a low over east-central MN, with a
    cold front extending southwestward into south-central NE before
    arcing back westward into far northeast CO and northwestward into
    central WY. This surface low, which is associated with the Upper
    Midwest shortwave trough, is forecast to progress eastward
    throughout the day, while gradually weakening. As it does, the cold
    front is expected to progress southeastward/southward, although the
    western portion of the front will gradually slow and eventually
    become stationary from southwest KS into northern MO this evening.
    Ascent along and atop this frontal zone will be the focus for
    potential isolated severe thunderstorm development this evening.

    ...Northern/central Missouri into central Illinois...
    Some modest low-level moisture advection is anticipated across the
    southern and central Plains today ahead of the southward progressing
    cold front. However, any notable low-level moisture (i.e. 60+ deg F
    dewpoints) will remain well south over south TX. This limited
    low-level moisture coupled with strong heating and mixing, should
    keep the airmass across the region capped through the afternoon and
    into the early evening. Thereafter, strengthening warm-air advection
    across the stalled front will combine with steep mid-level lapse
    rates to support moderate buoyancy and limited convective inhibition
    for parcels rooted around 700 to 800 mb. Cloud-bearing layer shear
    is sufficient for organization of any deeper, more sustained
    updrafts, and a few storms capable of isolated hail and/or damaging
    gusts are possible.

    ...Northern California/southwest Oregon...
    Thunderstorms are expected along the northern periphery of the upper
    low off the central CA coast. Increasing mid-level moisture and cold
    mid-level temperatures will support modest buoyancy amid moderate
    easterly flow aloft, supporting the potential for small hail and
    gusty winds with these westward progressing storms during the late afternoon/early evening. Even so, overall severe coverage is still
    expected to be less than 5%.

    ..Mosier/Dean.. 05/03/2026

    $$

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  • From COD Weather Processor@1:2320/107 to wx-storm@lists.illinois.edu on Sunday, May 03, 2026 16:31:09
    ACUS01 KWNS 031631
    SWODY1
    SPC AC 031629

    Day 1 Convective Outlook
    NWS Storm Prediction Center Norman OK
    1129 AM CDT Sun May 03 2026

    Valid 031630Z - 041200Z

    ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS THE
    MIDDLE MISSISSIPPI VALLEY...

    ...SUMMARY...
    Isolated severe storms capable of hail and gusty winds are possible
    mainly this evening across northern/eastern Missouri into
    south-central Illinois.

    ...Northern/eastern Missouri into south-central Illinois...
    Airmass modification and modest-caliber moist advection will occur north-northeastward into the region along and south of a
    decelerating southeastward-moving front. The limited low-level
    moisture, coupled with strong heating and mixing, should keep the
    airmass across the region capped through the afternoon. However,
    toward/after sunset, sufficient moistening atop the decoupling
    boundary layer should support increasing thunderstorm development
    this evening. Convection will tend to be rooted around 750-850 mb,
    and while elevated buoyancy will not be robust, the steep lapse
    rates could yield some severe hail (and possibly gusty winds) in the
    presence of 40+ kt shear through the cloud-bearing layer.

    ...Far South Florida...
    While a couple of strong storms could occur through the afternoon,
    cloud cover and an increasingly prevalent post-frontal regime, along
    with weak lapse rates in the cloud-bearing layer, should tend to
    limit storm intensity inland.

    ...Northern California/southwest Oregon...
    Thunderstorms are expected along the northern periphery of the upper
    low off the central California coast. Increasing mid-level moisture
    and cold mid-level temperatures will support modest buoyancy amid
    moderate easterly flow aloft, supporting the potential for small
    hail and gusty winds with these westward progressing storms during
    the late afternoon and early evening. However, organized severe
    storm potential is expected to remain low.

    ..Guyer/Chalmers.. 05/03/2026

    $$

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  • From COD Weather Processor@1:2320/107 to wx-storm@lists.illinois.edu on Sunday, May 03, 2026 19:24:11
    ACUS01 KWNS 031924
    SWODY1
    SPC AC 031922

    Day 1 Convective Outlook
    NWS Storm Prediction Center Norman OK
    0222 PM CDT Sun May 03 2026

    Valid 032000Z - 041200Z

    ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS FOR PORTIONS OF
    CENTRAL MISSOURI INTO CENTRAL AND SOUTHERN ILLINOIS...

    ...SUMMARY...
    Isolated severe storms capable of hail and gusty winds are possible
    mainly this evening across northern/eastern Missouri into
    south-central Illinois.

    ...20Z Update...
    The previous forecast (see below) remains on track.

    ..Squitieri.. 05/03/2026

    .PREV DISCUSSION... /ISSUED 1129 AM CDT Sun May 03 2026/

    ...Northern/eastern Missouri into south-central Illinois...
    Airmass modification and modest-caliber moist advection will occur north-northeastward into the region along and south of a
    decelerating southeastward-moving front. The limited low-level
    moisture, coupled with strong heating and mixing, should keep the
    airmass across the region capped through the afternoon. However,
    toward/after sunset, sufficient moistening atop the decoupling
    boundary layer should support increasing thunderstorm development
    this evening. Convection will tend to be rooted around 750-850 mb,
    and while elevated buoyancy will not be robust, the steep lapse
    rates could yield some severe hail (and possibly gusty winds) in the
    presence of 40+ kt shear through the cloud-bearing layer.

    ...Far South Florida...
    While a couple of strong storms could occur through the afternoon,
    cloud cover and an increasingly prevalent post-frontal regime, along
    with weak lapse rates in the cloud-bearing layer, should tend to
    limit storm intensity inland.

    ...Northern California/southwest Oregon...
    Thunderstorms are expected along the northern periphery of the upper
    low off the central California coast. Increasing mid-level moisture
    and cold mid-level temperatures will support modest buoyancy amid
    moderate easterly flow aloft, supporting the potential for small
    hail and gusty winds with these westward progressing storms during
    the late afternoon and early evening. However, organized severe
    storm potential is expected to remain low.

    $$

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  • From COD Weather Processor@1:2320/107 to wx-storm@lists.illinois.edu on Monday, May 04, 2026 00:42:11
    ACUS01 KWNS 040042
    SWODY1
    SPC AC 040040

    Day 1 Convective Outlook
    NWS Storm Prediction Center Norman OK
    0740 PM CDT Sun May 03 2026

    Valid 040100Z - 041200Z

    ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS FOR PORTIONS OF
    CENTRAL MISSOURI INTO CENTRAL AND SOUTHERN ILLINOIS...

    ...SUMMARY...
    Isolated severe storms capable of hail and gusty winds are possible
    this evening across northern/eastern Missouri into south-central
    Illinois.

    ...Synopsis...
    Current surface observations and mesoanalysis show modest air mass
    modification into central Missouri, where dew points are in the mid
    to upper 40s near the I-70 corridor. Visible satellite has shown
    some cumulus development over the last hour. A weak cold front
    continues to slowly sag southward. Guidance suggests that isolated
    thunderstorm development will be possible near this boundary this
    evening over the next couple of hours with the increasing low-level
    jet. These are expected to be elevated, rooted largely in the
    850-700 mb layer, where some marginal instability with cooling
    temperatures aloft and steep lapse rates may support a few instances
    of hail and strong to severe wind.

    Low top convection within a plume of steep low to mid-level lapse
    rates across South Dakota and Nebraska continues to track eastward,
    with a history of producing gusts 50-60 mph. These have been
    generally weakening and moving into drier air. Occasional stronger
    gusts may continue given the steep lapse rate environment.

    ..Thornton.. 05/04/2026

    $$

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  • From COD Weather Processor@1:2320/107 to wx-storm@lists.illinois.edu on Monday, May 04, 2026 06:00:14
    ACUS01 KWNS 040600
    SWODY1
    SPC AC 040558

    Day 1 Convective Outlook
    NWS Storm Prediction Center Norman OK
    1258 AM CDT Mon May 04 2026

    Valid 041200Z - 051200Z

    ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS PORTIONS
    OF THE MIDWEST INTO THE CENTRAL/SOUTHERN PLAINS...

    ...SUMMARY...
    Strong to severe thunderstorms capable of large hail and damaging
    wind are possible across portions of the Midwest late Monday
    afternoon into Monday night. A conditional threat for severe storms
    with large to very large hail extends into portions of the
    central/southern Plains.

    ...Synopsis...
    Strengthening mid-level flow will move out of Canada today,
    deepening the Eastern US trough, with a surface low developing
    across Ontario and a cold front shifting south across the northern
    Plains into the central Plains and Midwest. Across the west, flow
    will strengthen in within a cutoff low just off the shore of
    California before overspreading portions of the Southwest into the
    Southern Plains. A surface low is expected to develop across Kansas,
    with a dryline extending south into Oklahoma/north Texas. Areas of
    strong to severe storms will be possible from the Midwest into
    portions of eastern Kansas and south into Oklahoma/northern Texas.

    ...Eastern Kansas into Mid-Mississippi Valley...
    Thunderstorm development will likely be delayed until the late afternoon/evening across eastern Kansas into Missouri owing to
    strong MLCIN and generally weak forcing. Daytime heating and dew
    points in the mid 50s to 60s should yield moderate MLCAPE across a
    region from eastern Kansas northward into Missouri and western
    Illinois. As the low-level jet increases into the evening with the
    cold front shifting south, scattered thunderstorm development is
    expected. Initially, strongly sheared profiles and steep lapse rates
    will support supercells capable of large hail and damaging wind,
    primarily across eastern Kansas. Through time as additional storms
    develop and cluster along the front, the risk for damaging wind may
    increase. A few CAM members suggest a few clusters/bowing segments
    may move across northern Missouri and west-central Illinois, though
    there is disagreement in location/timing. A corridor of higher wind probabilities and upgrade to Slight may be warranted as details
    become clearer.

    ...Lower Great Lakes Vicinity...
    Scattered thunderstorm development will continue further north into
    the Great Lakes region along the cold front. Moisture becomes more
    limited with northern extent which may limit the severe threat.
    However, strong flow aloft and steep lapse rates may still support
    downward mixing and swaths of strong to severe wind.

    ...South-central Kansas into Oklahoma and northern Texas...
    A more conditional threat for storms will exist along the dryline
    across southern Kansas into central Oklahoma and northern Texas.
    Strong daytime heating is expected across this region along and
    behind the dryline. Forecast sounding comparison indicates the
    dryline circulation will be strong and deep through the afternoon.
    Mid-level capping will likely inhibit convection until stronger flow
    aloft overspreads the region by the late afternoon/evening. The
    low-level jet will also strengthen at this time, with MLCIN eroding.
    It is possible that an isolated supercell or two could develop and
    produce large to very large hail (some 2+ inches). The best signal
    for this is near the Red River in southern Oklahoma/northern Texas.
    However, a few members do have development further north across
    northern Oklahoma and into southeastern Kansas.

    ..Thornton/Lyons.. 05/04/2026

    $$

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  • From COD Weather Processor@1:2320/107 to wx-storm@lists.illinois.edu on Monday, May 04, 2026 12:54:17
    ACUS01 KWNS 041254
    SWODY1
    SPC AC 041252

    Day 1 Convective Outlook
    NWS Storm Prediction Center Norman OK
    0752 AM CDT Mon May 04 2026

    Valid 041300Z - 051200Z

    ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FROM NORTHEAST
    KANSAS ACROSS NORTHERN/CENTRAL MISSOURI INTO WEST-CENTRAL
    ILLINOIS...

    ...SUMMARY...
    Strong to severe thunderstorms capable of large hail and damaging
    wind are possible across portions of the Midwest this afternoon into
    tonight. A conditional threat for severe storms with large to very
    large hail extends into portions of the central/southern Plains.

    ...Synopsis...
    Early-morning satellite imagery shows a large upper low off the
    central CA coast, with an extensive fetch of southwesterly flow
    aloft from the base of this low through northern Mexico and the
    Southwest States into the southern High Plains. A deep cyclone
    exists over central Canada as well. Between these two primary
    features, a low-amplitude shortwave trough is currently moving
    southeastward across NE.

    Several shortwave troughs are forecast to rotate around the Canadian
    cyclone, contributing to some deepening and eastward progression. An
    associated surface low, currently over northwestern Ontario, will
    move eastward as well. The deepening of the upper trough across the
    northern Plains and progression of the surface low will force a cold
    front southward/southeastward across the Upper Midwest and Middle MO
    Valley by this evening, and through the central Plains, and Lower MO
    and Mid MS Valleys by early tomorrow. Increasing low-level moisture
    is anticipated ahead of this cold front, supporting the potential
    for thunderstorms as this front interacts with this moisture and
    associated buoyancy.

    ...Eastern KS into Mid MS Valley and Lower MI...
    Thunderstorm development is anticipated during the afternoon, both
    along the front, which should extend through southern WI and
    eastern/southern IA, and within the warm-air advection regime ahead
    of the front. Thunderstorms along the front will initially be
    displaced north of the better shear and buoyancy, so somewhat
    transient updraft structures and/or frontal undercutting will likely
    limit storm severity. Even so, high cloud bases and a deeply mixed
    boundary layer could result in a few strong gusts. Later in the
    evening, more storm development appears likely on the front as it
    moves into eastern KS and northern/central MO. Here, stronger shear
    and buoyancy should support more robust updrafts and a relatively
    higher probability for severe storms. Large hail is the primary
    risk.

    Any thunderstorms that develop within the warm-air advection regime
    ahead of the front during the afternoon and early evening should
    interact with greater buoyancy (particularly from northeast IL,
    northern IL and southern Lower MI where less boundary-layer mixing
    could result in slightly higher dewpoints) and moderate vertical
    shear. A few stronger, more organized storms are possible in this
    area, although weaker upper flow could limit discreteness and result
    in a trend towards a more clustered storm mode.

    ...Central Kansas into Oklahoma and northern Texas...
    A sharp dryline is expected to develop from central KS
    south-southwestward into northwest TX. Given the veering surface
    winds, convergence along the dryline will likely be modest
    throughout much of the afternoon. However, some backing is possible
    during the evening as a surface low moves eastward across southwest
    KS towards northwest OK. Strong diurnal heating will likely erode
    most convective inhibition by the early evening, while steep lapse
    rates contribute to moderate buoyancy. These factors could be enough
    to force isolated initiation on the dryline from central KS into
    northwest TX. Upper-level flow will be strengthening across the
    region throughout the period, and any storms that do form will have
    ample deep-layer shear to support supercells. Large to very large
    hail would be the primary risk early in the convective cycle, with
    dry mid-levels also supporting strong downdrafts as storms begin to
    weaken and collapse.

    ..Mosier/Dean.. 05/04/2026

    $$

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  • From COD Weather Processor@1:2320/107 to wx-storm@lists.illinois.edu on Monday, May 04, 2026 16:32:49
    ACUS01 KWNS 041632
    SWODY1
    SPC AC 041630

    Day 1 Convective Outlook
    NWS Storm Prediction Center Norman OK
    1130 AM CDT Mon May 04 2026

    Valid 041630Z - 051200Z

    ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FROM THE LOWER
    MISSOURI VALLEY INTO THE SOUTHERN GREAT LAKES...

    ...SUMMARY...
    Scattered severe thunderstorms capable of large hail and damaging
    wind gusts are possible across portions of the Midwest this
    afternoon into tonight. A conditional threat for severe storms with
    large to very large hail extends into portions of the
    central/southern Plains.

    ...IL into the southern Great Lakes...
    A mid-level vorticity maximum over the lower MO Valley is forecast
    to move east across IL through the late afternoon and into IN-OH
    tonight. An associated speed maximum at 700 mb will intensify and
    overspread IL (40-50 kt) east into the southern Great Lakes while a
    pronounced strengthening of 850-mb flow (50 kt) occurs during the
    21-03z period. Cold mid-level temperatures (-18 deg C at 500 mb)
    will act to offset initially meager moisture. Model guidance varies considerably regarding moisture quality with ample spread amongst
    different model cores/PBL schemes. However, it seems a narrow
    corridor of lower to mid 50s surface dewpoints will extend
    east-northeast from the lower MO Valley into the southern Great
    Lakes by mid to late afternoon. Forecast soundings show weak to
    moderate buoyancy (500-1250 J/kg MLCAPE). Morning model guidance
    shows widely scattered to scattered storms developing within the
    warm conveyor during peak heating as convective inhibition erodes.
    Have expanded the Slight Risk farther east into this region to
    account for a hail/wind risk with the stronger storms. Uncertainty
    remains regarding quality of boundary-layer moisture across the
    northern third of IN into northwest OH where hodographs become
    enlarged later this afternoon into the early evening. Will
    re-evaluate the tornado risk for the 20 UTC outlook if in fact
    moisture quality seems sufficient for a focused, short-duration
    tornado risk across the aforementioned corridor.

    ...Eastern KS into the Mid MS Valley...
    Thunderstorm development is anticipated during the afternoon along a
    cold forecast to extend through southern WI and
    eastern/southern IA. Thunderstorms along the front will initially be
    displaced north of the better shear and buoyancy, so somewhat
    transient updraft structures and/or frontal undercutting will likely
    limit storm severity. Even so, high cloud bases and a deeply mixed
    boundary layer could result in a few strong gusts. Later in the
    evening, more storm development appears likely on the front as it
    moves into eastern KS and northern/central MO. Here, stronger shear
    and buoyancy should support more robust updrafts and a relatively
    higher probability for severe storms. Large to very large hail is
    the primary risk.

    ...Central Kansas into Oklahoma and northern Texas...
    A dryline will extend from central KS south-southwestward into
    northwest TX by mid afternoon as a surface low evolves near the TX Panhandle/OK/KS border region. Strong diurnal heating will likely
    erode most convective inhibition by the early evening, while steep
    lapse rates contribute to moderate buoyancy along the dryline.
    Isolated thunderstorms are possible on the dryline from central KS
    into northwest TX during the 22-02 UTC period. Veering and
    strengthening flow with height beneath 100-kt westerly 200-mb flow
    will support supercells. Isolated large to very large hail will be
    the primary risk with the stronger storms, although severe gusts are
    also possible.

    ..Smith/Chalmers.. 05/04/2026

    $$

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  • From COD Weather Processor@1:2320/107 to wx-storm@lists.illinois.edu on Monday, May 04, 2026 19:34:48
    ACUS01 KWNS 041934
    SWODY1
    SPC AC 041933

    Day 1 Convective Outlook
    NWS Storm Prediction Center Norman OK
    0233 PM CDT Mon May 04 2026

    Valid 042000Z - 051200Z

    ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PORTIONS OF
    THE MIDWEST INTO THE OHIO VALLEY...

    ...SUMMARY...
    Scattered severe thunderstorms capable of large hail and damaging
    wind gusts are possible across portions of the Midwest this
    afternoon into tonight. A conditional threat for severe storms with
    large to very large hail extends into portions of the
    central/southern Plains.

    ...20Z Update...
    The previous forecast remains largely on track. Only minor changes
    were made to the thunder and severe probabilities to reflect the
    latest trends in observations and high resolution model guidance.

    ..Squitieri.. 05/04/2026

    .PREV DISCUSSION... /ISSUED 1130 AM CDT Mon May 04 2026/

    ...IL into the southern Great Lakes...
    A mid-level vorticity maximum over the lower MO Valley is forecast
    to move east across IL through the late afternoon and into IN-OH
    tonight. An associated speed maximum at 700 mb will intensify and
    overspread IL (40-50 kt) east into the southern Great Lakes while a
    pronounced strengthening of 850-mb flow (50 kt) occurs during the
    21-03z period. Cold mid-level temperatures (-18 deg C at 500 mb)
    will act to offset initially meager moisture. Model guidance varies considerably regarding moisture quality with ample spread amongst
    different model cores/PBL schemes. However, it seems a narrow
    corridor of lower to mid 50s surface dewpoints will extend
    east-northeast from the lower MO Valley into the southern Great
    Lakes by mid to late afternoon. Forecast soundings show weak to
    moderate buoyancy (500-1250 J/kg MLCAPE). Morning model guidance
    shows widely scattered to scattered storms developing within the
    warm conveyor during peak heating as convective inhibition erodes.
    Have expanded the Slight Risk farther east into this region to
    account for a hail/wind risk with the stronger storms. Uncertainty
    remains regarding quality of boundary-layer moisture across the
    northern third of IN into northwest OH where hodographs become
    enlarged later this afternoon into the early evening. Will
    re-evaluate the tornado risk for the 20 UTC outlook if in fact
    moisture quality seems sufficient for a focused, short-duration
    tornado risk across the aforementioned corridor.

    ...Eastern KS into the Mid MS Valley...
    Thunderstorm development is anticipated during the afternoon along a
    cold forecast to extend through southern WI and
    eastern/southern IA. Thunderstorms along the front will initially be
    displaced north of the better shear and buoyancy, so somewhat
    transient updraft structures and/or frontal undercutting will likely
    limit storm severity. Even so, high cloud bases and a deeply mixed
    boundary layer could result in a few strong gusts. Later in the
    evening, more storm development appears likely on the front as it
    moves into eastern KS and northern/central MO. Here, stronger shear
    and buoyancy should support more robust updrafts and a relatively
    higher probability for severe storms. Large to very large hail is
    the primary risk.

    ...Central Kansas into Oklahoma and northern Texas...
    A dryline will extend from central KS south-southwestward into
    northwest TX by mid afternoon as a surface low evolves near the TX Panhandle/OK/KS border region. Strong diurnal heating will likely
    erode most convective inhibition by the early evening, while steep
    lapse rates contribute to moderate buoyancy along the dryline.
    Isolated thunderstorms are possible on the dryline from central KS
    into northwest TX during the 22-02 UTC period. Veering and
    strengthening flow with height beneath 100-kt westerly 200-mb flow
    will support supercells. Isolated large to very large hail will be
    the primary risk with the stronger storms, although severe gusts are
    also possible.

    $$

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  • From COD Weather Processor@1:2320/107 to wx-storm@lists.illinois.edu on Tuesday, May 05, 2026 00:54:20
    ACUS01 KWNS 050054
    SWODY1
    SPC AC 050052

    Day 1 Convective Outlook
    NWS Storm Prediction Center Norman OK
    0752 PM CDT Mon May 04 2026

    Valid 050100Z - 051200Z

    ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FROM EASTERN
    KANSAS INTO NORTHERN INDIANA AND NORTHWEST OHIO...

    ...SUMMARY...
    Widely scattered severe thunderstorms capable of large hail and
    damaging wind gusts are possible from eastern Kansas into the
    portions of the Ohio Valley this evening into tonight. A
    conditional threat for severe storms with large to very large hail
    extends into portions of southern Plains through the remainder of
    the evening.

    ...Mid-Mississippi and Ohio Valleys....

    Widely scattered, strong to severe storms are ongoing this evening
    along and ahead of a progressive cold front from southern lower MI
    into northern IL and far southeast IA with visible satellite
    indicating additional storm attempts into portions of northern MO. A
    separate area of thunderstorms is ongoing within the open warm
    sector east of St. Louis where hail up two inches in diameter has
    been reported. In the absence of more substantial boundary-layer
    moisture content, 00z observed soundings revealed the presence of
    steep low/mid-level lapse rates are largely contributing to MLCAPE
    of around 1000 J/kg. Meanwhile, the accompanying kinematic
    environment features a vertically veering wind profile with around
    40 kt of effective bulk shear magnitudes and modestly strong
    low-level shear (effective SRH of 150-200 m2/s2).

    Current thinking is that ongoing storms will remain capable of
    isolated occurrences of large hail and locally damaging wind gusts
    for the next few hours as increasing moisture content along a
    nocturnal low-level jet offsets cooling in the boundary layer. The
    threat should tend to diminish overnight as the boundary layer
    gradually stabilizes.

    For additional information on near-term details, see MCDs 640 and
    641.


    ...Eastern Kansas into western Missouri...

    Isolated to widely scattered thunderstorms have persisted this
    evening across portions of western into central KS, aided by a weak
    mid-level impulse moving through the central High Plains. A number
    of high-resolution models suggest that activity will intensify later
    this evening into tonight as it drifts east of the I-35 corridor and
    encounters an increasingly unstable air mass in place across eastern
    KS into western MO. A strengthening low-level jet will enhance
    moisture transport into the growing complex of storms with large
    hail being the primary hazard initially. With time, the models
    suggest upscale growth into one or more forward-propagating clusters
    with an increased risk for damaging wind gusts.

    ..Mead.. 05/05/2026

    $$

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  • From COD Weather Processor@1:2320/107 to wx-storm@lists.illinois.edu on Tuesday, May 05, 2026 05:37:51
    ACUS01 KWNS 050537
    SWODY1
    SPC AC 050536

    Day 1 Convective Outlook
    NWS Storm Prediction Center Norman OK
    1236 AM CDT Tue May 05 2026

    Valid 051200Z - 061200Z

    ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS CENTERED OVER
    ARKANSAS AND EXTENDING FROM NORTHEAST TEXAS INTO WESTERN
    TENNESSEE...

    ...SUMMARY...
    Widely scattered severe storms are possible Tuesday afternoon into
    Tuesday night from northeast Texas into western Tennessee, with the
    main threat centered over Arkansas. The strongest storms will be
    capable of large hail, damaging winds, and a few tornadoes. More
    isolated, strong to severe storms are possible across parts of the
    Northeast.

    ...Synopsis...

    A vigorous, mid-level low over Ontario this evening is forecast to
    evolve into an open wave while translating east into Quebec on
    Tuesday. An accompanying belt of strong, mid/upper-level winds will
    overspread the lower Great Lakes and northern New England in tandem
    with modest height falls related to a vorticity maximum pivoting
    through the base of the parent system. Elsewhere, a mid-level low
    currently along the CA coast is expected to weaken while shifting
    through the lower-CO Valley to the vicinity of the Four Corners
    region. A belt of 50-70 kt winds at 500 mb are forecast downstream
    from that feature, extending from the southern Plains into the Mid
    South on Tuesday afternoon into evening.

    In the low levels, a cold front is expected to extend from southeast
    Quebec through the OH and mid-MS Valleys to low pressure over OK
    Tuesday morning. The northern extension of the boundary will move
    into the lower Great Lakes and northern New England during the peak
    of the diurnal heating cycle. The segment of the front across the
    Ozarks and Ozark Plateau may be temporarily displaced to the south
    Tuesday morning due to overnight thunderstorm activity. However by
    afternoon, the front is expected to refocus in the vicinity of the
    MO-AR border, ahead of a weakening surface low moving through
    eastern OK into western AR. The western extension of the cold front
    trailing the surface low is expected to advance southeast through
    the Red River Valley.

    ...Northeast Texas into the southern Missouri and western
    Tennessee...

    As mentioned in the synopsis, a complex of thunderstorms may be
    ongoing at the start of the forecast period across portions of MO
    into northern AR. That activity is expected to shift east of the
    area by late morning or early afternoon, with some lingering shower
    and thunderstorm development occurring to the north of the front in
    central MO. In the wake of the early-day convection, HREF cloud
    forecasts indicate the potential for considerable high-level clouds
    and pockets of thicker low-cloudiness, which could limit the
    potential for stronger diabatic warming within the pre-frontal air
    mass. Nonetheless, the presence of boundary-layer dewpoints in the
    60s in conjunction with an elevated-mixed layer (EML) plume will
    support a moderately unstable air mass by afternoon with MLCAPE of
    1000-2000 J/kg.

    Neutral to slight height rises are forecast in the mid levels during
    the peak of the diurnal heating cycle with model forecast soundings
    indicating considerable capping at the base of the EML. As such,
    eventual storm coverage remains uncertain. The 00z high-resolution
    models suggest that isolated to widely scattered thunderstorms will
    become increasingly likely by late afternoon or early evening along
    the frontal segment along the MO-AR border, immediately
    east/northeast of the surface low. Additional, isolated storm
    development also appears possible from the vicinity of the surface
    low southwest along the cold front into northeast TX, mainly during
    the evening hours.

    The favorable overlap of moderate instability and strong deep-layer
    shear will favor supercell storm modes, especially given the
    anticipated weak forcing for ascent. Large hail will be the
    predominant severe-weather hazard initially. A few tornadoes appear
    possible across portions of northern AR, potentially into western TN
    from late afternoon through the evening association with any
    sustained supercells. Here, the presence of a 35-40 kt low-level jet
    will yield effective SRH of 200-300 m2/s2 amidst a moist/low-LCL
    environment. Storms may eventually grow upscale into clusters, at
    which point damaging winds would become a growing concern.

    ...Lower Great Lakes into northern New England...

    Moisture advection occurring along a southwesterly low-level jet
    will allow dewpoints to rise into the 50s within the pre-frontal
    warm sector on Tuesday. And while mid-level lapse rates are not
    expected to be particularly steep, the moisture increase combined
    with daytime heating and the resultant steepening of low-level lapse
    rates will result in MLCAPE of 500 to perhaps 1000 J/kg. Increasing
    height falls aloft and convergence/lift along the cold front are
    expected to support surface-based storm development by early
    afternoon within the destabilizing air mass across portions of
    upstate NY. The storms will quickly overspread northern portions of
    VT, NH, and ME during the afternoon into early evening.

    The 00z high-resolution models indicate the potential for transient
    supercell and bowing structures, which appears reasonable given the
    presence of a relatively strong, deep-layer wind field. In that
    scenario, isolated occurrences of damaging winds and perhaps some
    marginally severe hail appear possible. The tornado threat will be
    conditional on sufficient instability to support more sustained
    supercell structures. A level 1/Marginal Risk will be maintained;
    however, if it becomes apparent that stronger instability will
    develop than is currently anticipated, an upgraded to level 2/Slight
    Risk may become necessary.

    ..Mead/Lyons.. 05/05/2026

    $$

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  • From COD Weather Processor@1:2320/107 to wx-storm@lists.illinois.edu on Tuesday, May 05, 2026 12:53:52
    ACUS01 KWNS 051253
    SWODY1
    SPC AC 051252

    Day 1 Convective Outlook
    NWS Storm Prediction Center Norman OK
    0752 AM CDT Tue May 05 2026

    Valid 051300Z - 061200Z

    ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS CENTERED OVER
    ARKANSAS AND EXTENDING FROM NORTHEAST TEXAS INTO WESTERN
    TENNESSEE...

    ...SUMMARY...
    Widely scattered severe storms are possible Tuesday afternoon into
    Tuesday night from northeast Texas into western Tennessee, with the
    main threat centered over Arkansas. The strongest storms will be
    capable of large hail, damaging winds, and a few tornadoes. More
    isolated strong to severe storms are possible across parts of the
    Northeast.

    ...Northeast TX into the Mid-South...
    Regional radar imagery shows a cluster of showers and thunderstorms
    moving across central/northeast AR. Outflow associated with this
    cluster stretches from north of LIT northwestward between FSM and
    FYV into northeast OK. Surface analysis also places a low over
    western OK. A cold front extends east-northeastward from this low
    through far northeast OK and southern MO, and a dryline extends
    southwestward from the low through the Permian Basin. These
    boundaries, particularly the cold front and outflow boundary, could
    act as a focal points for redevelopment as the airmass across the
    region destabilizes amid heating and low-level moisture advection
    this afternoon.

    A combination of afternoon temperatures in the low 80s, dewpoints in
    the mid 60s, and steep mid-level lapse rates will result in moderate
    buoyancy (i.e. MLCAPE around 1500 to 2000 J/kg) within the warm
    sector this afternoon. Convergence along the front will be modest
    and large-scale height rises are anticipated. Some weak capping may
    prevail as well, particularly if the current cloudiness persists.
    These factors introduce notable uncertainty into the forecast,
    particularly regarding overall storm coverage. Seemingly, these
    factors should contribute to a widely scattered, but discrete, storm
    mode. The placement and evolution of the outflow may become apparent
    as heating begins, with observable trends in cloud cover possible as
    well. These factors could potentially reveal a corridor of higher
    storm coverage. However, confidence in the placement of such a
    corridor is currently low, precluding the introduction of any higher probabilities.

    That being said, the kinematic environment should be very supportive
    of supercells this afternoon/evening, with strong upper flow
    resulting in bulk shear around 60 kt. Any storms that do mature
    should be severe and capable of all hazards. Large to very large
    hail (i.e. 2"+) is possible early in each storm's convective cycle.
    Tornadoes are also possible, particularly from central AR into
    western TN where the low/mid-level flow will be strongest. A strong
    tornado is possible with a sustained discrete supercell. Storms may
    eventually grow upscale into clusters, at which point damaging winds
    would become the primary severe risk.

    ...Lower Great Lakes into northern New England...
    Early morning surface analysis placed a low over southeast Lower MI,
    along a cold front that extends from central Quebec southwestward
    through southern IL. This low is forecast to progress northeastward
    along the St. Lawrence Valley vicinity as the cold front also
    progresses eastward in response to an eastward shift of the parent
    cyclone from northern Ontario into northern Quebec. Modest low-level
    moisture will advect northeastward into the Lower Great Lakes and
    Northeast ahead of this cold front, with low 50s dewpoints likely
    reaching as far north as ME. This low-level moisture coupled with
    afternoon temperatures in the 70s will support modest buoyancy,
    despite poor lapse rates. Thunderstorms are anticipated along and
    ahead of the eastward-progressing front as it moves into the
    destabilized airmass from the Lower Great Lakes into northern ME.

    Strong deep-layer vertical will be in place, supported by relatively
    deep southwesterly flow, suggesting the potential for organized
    storm structures. However, this flow will be largely parallel to the
    boundary, with a bowing linear mode expected to be dominant (as
    shown by much of the convection-allowing guidance). Damaging gusts
    will be possible with the strongest storms, although transient
    updraft strength should keep the overall coverage and intensity
    modest. Isolated hail is possible with a few storms as well.
    Predominantly linear mode should keep the tornado risk low, although
    a low-probability threat still exists, particularly if a pocket of
    strong buoyancy can develop across Upstate NY.

    ..Mosier/Dean.. 05/05/2026

    $$

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  • From COD Weather Processor@1:2320/107 to wx-storm@lists.illinois.edu on Tuesday, May 05, 2026 16:32:55
    ACUS01 KWNS 051632
    SWODY1
    SPC AC 051631

    Day 1 Convective Outlook
    NWS Storm Prediction Center Norman OK
    1131 AM CDT Tue May 05 2026

    Valid 051630Z - 061200Z

    ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS CENTERED OVER
    ARKANSAS AND EXTENDING FROM NORTHEAST TEXAS INTO WESTERN
    TENNESSEE...

    ...SUMMARY...
    Widely scattered severe storms are possible this afternoon through
    this evening from north Texas, much of Arkansas, and into western
    Tennessee. Large to very large hail, severe gusts, and a few
    tornadoes are possible.

    ...Northeast TX into the Mid-South...
    Radar mosaic shows an MCV moving east across far western KY with a
    band of weak thunderstorms extending south and west across western
    TN. Convective outflow associated with the showers/thunderstorms
    extends from east-west near I-40 across AR into eastern OK where it
    intersects a triple point over central OK. A cold front is draped
    southwest to northeast along the I-44 corridor from western north TX northeastward into the Ozarks.

    Visible-satellite imagery late this morning shows extensive cloud
    cover from northeast TX northeastward into AR and the lower OH
    Valley. A plume of richer moisture at the surface is denoted by mid
    to upper 60s deg F dewpoints protruding north from east-central TX
    into north TX and southeast OK. Further moistening of low levels
    via southerly return flow is forecast beneath a capping inversion
    around 850 mb sampled by the 12 UTC Forth Worth, TX raob.

    Gradual boundary layer heating will result in surface temperatures
    warming into the upper 80s over north TX with muted heating farther
    northeast over AR where persistent cloud cover will inhibit stronger
    heating. Model guidance shows MLCAPE ranging from 500-1500 J/kg
    from northeast AR southwestward into southwest AR, and upwards of
    3000 J/kg MLCAPE across north TX by mid-late afternoon. Convergence
    along the front will be modest and large-scale height rises are
    anticipated. However, thinning clouds near the OK/AR border and the
    erosion of convective inhibition as convective temperatures are
    breached over north TX will result in isolated to scattered storms
    developing during 20-23 UTC period. Initial supercell mode is
    forecast over north TX with some clustering expected during the
    evening. The tornado risk over north TX will likely be limited by
    relatively weak low-level shear but strong mid to high-level flow
    will promote large to very large hail growth (1 to 3 inches in
    diameter). Farther northeast, isolated to scattered storms are
    forecast to develop east of the eastward-migrating surface low and
    near the front by the mid-late afternoon. HRRR time-lagged runs
    this morning show a few supercells with one more longer track storms
    moving developing and moving east across central AR in a larger SRH environment. An all hazards severe risk may accompany the stronger
    storms in AR beginning later this afternoon and possibly persisting
    through the evening as this activity moves east towards the MS
    River. A strong tornado is possible with a sustained discrete
    supercell. Upscale growth into a cluster or band of storms is
    expected as moderately strong southwesterly 850 to 700-mb flow is
    maintained across the Mid South. Damaging gusts and perhaps a
    lingering tornado risk will possibly spread east tonight before
    storms weaken late.

    ...Lower Great Lakes into northern New England...
    A marginally moist airmass will advect northeastward into the Lower
    Great Lakes and Northeast ahead of an eastward-moving cold front,
    with low 50s dewpoints likely reaching as far north as ME. This
    low-level moisture coupled with afternoon temperatures in the 70s
    will support modest buoyancy, despite poor lapse rates.
    Thunderstorms are anticipated along and ahead of the
    eastward-progressing front as it moves into the destabilized airmass
    from the Lower Great Lakes into northern ME.

    Strong deep-layer vertical will be in place, supported by relatively
    deep southwesterly flow, suggesting the potential for organized
    storms. However, this flow will be largely parallel to the
    boundary, with linear structures favored. Damaging gusts will be
    possible with the strongest storms, although transient updraft
    strength should keep the overall coverage and intensity modest.
    Isolated hail is possible with a few storms as well. Predominantly
    linear mode should keep the tornado risk low, although a
    low-probability threat still exists, particularly if a pocket of
    strong buoyancy can develop across Upstate NY.

    ..Smith/Squitieri.. 05/05/2026

    $$

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  • From COD Weather Processor@1:2320/107 to wx-storm@lists.illinois.edu on Tuesday, May 05, 2026 19:48:27
    ACUS01 KWNS 051948
    SWODY1
    SPC AC 051946

    Day 1 Convective Outlook
    NWS Storm Prediction Center Norman OK
    0246 PM CDT Tue May 05 2026

    Valid 052000Z - 061200Z

    ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS NORTH TEXAS INTO
    WESTERN TENNESSEE...

    ...SUMMARY...
    Widely scattered severe storms are possible this afternoon through
    this evening from north Texas, much of Arkansas, and into western
    Tennessee. Large to very large hail, severe gusts, and a few
    tornadoes are possible.

    ...20z Update...
    The previous forecast largely remains on track with only minor
    adjustments made. Recent GOES imagery shows gradual clearing across
    northern TX into northwest LA and western AR with slow
    warming/moistening noted in surface observations. A stable layer
    remains evident in visible imagery across western AR, and a recent
    18 UTC SHV RAOB sampled a stronger capping inversion at 850 mb
    compared to what is depicted by latest high-res guidance. This casts
    some uncertainty on convective coverage across southwest AR;
    however, trends in time-lagged ensemble guidance and early high-res
    WoFS solutions continue to show reasonably high confidence in
    thunderstorm development along and north of the I-40 corridor in AR
    and downstream into northern MS, middle TN, and northwest AL later
    tonight. Although storm mode will likely transition to clusters and
    embedded semi-discrete cells after 06 UTC, some severe threat will
    likely persist into the early morning hours given adequate buoyancy
    and ample deep-layer wind shear. The eastern extent of the 5%
    wind/hail contours have been adjusted accordingly.

    Elsewhere, the forecast remains on track. See the previous
    discussion below and recently issued MCD #646 for additional
    details.

    ..Moore.. 05/05/2026

    .PREV DISCUSSION... /ISSUED 1131 AM CDT Tue May 05 2026/

    ...Northeast TX into the Mid-South...
    Radar mosaic shows an MCV moving east across far western KY with a
    band of weak thunderstorms extending south and west across western
    TN. Convective outflow associated with the showers/thunderstorms
    extends from east-west near I-40 across AR into eastern OK where it
    intersects a triple point over central OK. A cold front is draped
    southwest to northeast along the I-44 corridor from western north TX northeastward into the Ozarks.

    Visible-satellite imagery late this morning shows extensive cloud
    cover from northeast TX northeastward into AR and the lower OH
    Valley. A plume of richer moisture at the surface is denoted by mid
    to upper 60s deg F dewpoints protruding north from east-central TX
    into north TX and southeast OK. Further moistening of low levels
    via southerly return flow is forecast beneath a capping inversion
    around 850 mb sampled by the 12 UTC Forth Worth, TX raob.

    Gradual boundary layer heating will result in surface temperatures
    warming into the upper 80s over north TX with muted heating farther
    northeast over AR where persistent cloud cover will inhibit stronger
    heating. Model guidance shows MLCAPE ranging from 500-1500 J/kg
    from northeast AR southwestward into southwest AR, and upwards of
    3000 J/kg MLCAPE across north TX by mid-late afternoon. Convergence
    along the front will be modest and large-scale height rises are
    anticipated. However, thinning clouds near the OK/AR border and the
    erosion of convective inhibition as convective temperatures are
    breached over north TX will result in isolated to scattered storms
    developing during 20-23 UTC period. Initial supercell mode is
    forecast over north TX with some clustering expected during the
    evening. The tornado risk over north TX will likely be limited by
    relatively weak low-level shear but strong mid to high-level flow
    will promote large to very large hail growth (1 to 3 inches in
    diameter). Farther northeast, isolated to scattered storms are
    forecast to develop east of the eastward-migrating surface low and
    near the front by the mid-late afternoon. HRRR time-lagged runs
    this morning show a few supercells with one more longer track storms
    moving developing and moving east across central AR in a larger SRH environment. An all hazards severe risk may accompany the stronger
    storms in AR beginning later this afternoon and possibly persisting
    through the evening as this activity moves east towards the MS
    River. A strong tornado is possible with a sustained discrete
    supercell. Upscale growth into a cluster or band of storms is
    expected as moderately strong southwesterly 850 to 700-mb flow is
    maintained across the Mid South. Damaging gusts and perhaps a
    lingering tornado risk will possibly spread east tonight before
    storms weaken late.

    ...Lower Great Lakes into northern New England...
    A marginally moist airmass will advect northeastward into the Lower
    Great Lakes and Northeast ahead of an eastward-moving cold front,
    with low 50s dewpoints likely reaching as far north as ME. This
    low-level moisture coupled with afternoon temperatures in the 70s
    will support modest buoyancy, despite poor lapse rates.
    Thunderstorms are anticipated along and ahead of the
    eastward-progressing front as it moves into the destabilized airmass
    from the Lower Great Lakes into northern ME.

    Strong deep-layer vertical will be in place, supported by relatively
    deep southwesterly flow, suggesting the potential for organized
    storms. However, this flow will be largely parallel to the
    boundary, with linear structures favored. Damaging gusts will be
    possible with the strongest storms, although transient updraft
    strength should keep the overall coverage and intensity modest.
    Isolated hail is possible with a few storms as well. Predominantly
    linear mode should keep the tornado risk low, although a
    low-probability threat still exists, particularly if a pocket of
    strong buoyancy can develop across Upstate NY.

    $$

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  • From COD Weather Processor@1:2320/107 to wx-storm@lists.illinois.edu on Wednesday, May 06, 2026 00:49:58
    ACUS01 KWNS 060049
    SWODY1
    SPC AC 060048

    Day 1 Convective Outlook
    NWS Storm Prediction Center Norman OK
    0748 PM CDT Tue May 05 2026

    Valid 060100Z - 061200Z

    ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS SEVERE
    THUNDERSTORMS NORTH TEXAS INTO WESTERN TENNESSEE...

    ...SUMMARY...
    Widely scattered severe storms are possible this evening from north
    Texas, much of Arkansas, and into western Tennessee. Large to very
    large hail, severe gusts, and a few tornadoes are possible.

    ...Discussion...
    Two areas of thunderstorm development are noted this evening: one
    near the cold front extending across northwestern Arkansas and
    another southward into north Texas near the cold front interface
    with the dryline in central Texas. These two areas will be the
    targets of interest for severe storm development this evening.

    ...Arkansas...
    A cluster of elevated cells have developed in the vicinity of the
    cold front in northwestern Arkansas. These have been slow to mature,
    likely owning to remaining surface inhibition observed from NSSL
    LIFT soundings from central Arkansas. This is also observed in
    surface objective analysis, with moderate to strong CAPE in place
    across much of central/southern Arkansas. Hi-res guidance suggests
    that additional development will be likely through the evening. The
    shear profiles across the region are supportive of supercells, given
    strong deep layer shear at 65+ kts. If these cells can become
    surface based through time, the tornado risk will increase. Surface
    objective analysis indicates STP around 3-4 across southwestern
    Arkansas into central Arkansas. Through time, additional development
    along the front will become more linear and support an increase in
    damaging wind potential.

    ...North-Central and Northeastern Texas/Southwestern Texas...
    Thunderstorms have developed across the north side of the Dallas
    metro this evening near the interface of the dryline with surface
    boundaries and the cold front. Conditionally, if supercells develop
    across this region potential for large hail will be possible.

    Guidance also suggests convective development will be possible near
    the Mexico border in far southwestern Texas. A conditional risk for
    large to very large hail will extend into this region as well this
    evening.

    ..Thornton.. 05/06/2026

    $$

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  • From COD Weather Processor@1:2320/107 to wx-storm@lists.illinois.edu on Wednesday, May 06, 2026 05:51:32
    ACUS01 KWNS 060551
    SWODY1
    SPC AC 060549

    Day 1 Convective Outlook
    NWS Storm Prediction Center Norman OK
    1249 AM CDT Wed May 06 2026

    Valid 061200Z - 071200Z

    ...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS ACROSS PORTIONS
    OF NORTHERN LOUISIANA INTO CENTRAL MISSISSIPPI AND CENTRAL
    ALABAMA...

    ...SUMMARY...
    Scattered severe thunderstorms are expected this afternoon and
    evening from eastern Texas into the lower Mississippi and Tennessee Valleys/southern Appalachians. Supercells capable of all hazards
    will be possible across portions of central Mississippi and Alabama
    before a shift to a more widespread damaging wind risk into the late evening/overnight.

    ...Synopsis...
    A strong mid to upper-level jet will move across the mid Mississippi
    Valley into Tennessee and northward into the Ohio Valley through the
    period. At the surface, a cold front will sag southward from the
    southern Plains into the Gulf Coast states and north into the
    Mid-Atlantic region. Thunderstorm activity is expected to be ongoing
    along this boundary at the start of the period this morning across
    portions of Arkansas, northern Mississippi, and Tennessee. By the
    afternoon, additional development of severe storms is likely across
    portions of Louisiana into central Mississippi and central Alabama
    along and ahead of the cold front. Supercells capable of all hazards
    will be possible before trending to a damaging wind threat as storms
    grow upscale through the evening.

    ...Northern Louisiana, Mississippi, Alabama...
    Extensive mid-level cloud cover is expected to persist this morning
    across much of the Mississippi River Valley into portions of
    northern Louisiana/Alabama/Mississippi. Within the gradient of
    broken mid-level cloud cover across portions of south-central and
    southern Mississippi into central Alabama, filtered heating and
    strong warm air advection may promote a more favorable corridor of
    moderate MLCAPE values. Almost all hi-res guidance hints at the
    possibility of storms developing within the open warm sector by the
    afternoon, the primary mode being supercelluar. Within this
    corridor, a southwesterly low-level jet around 40-50 kts will also
    increase into the evening enlarging low-level hodographs and
    increasing potential for tornadoes. Should supercells be able to
    form and sustain within this environment, they would pose a risk for
    all hazards including strong tornadoes, large hail, and damaging
    winds. The Enhanced Risk was shifted southward to nudge into the
    region where there is better confidence that filtered heating will
    occur. Higher probabilities were considered, but details on morning
    cloud cover and air mass recovery into the afternoon lead to low
    confidence in introducing higher probabilities.

    As the front sags southward, storms will begin to cluster with
    tendency to grow upscale and an increasing damaging wind threat
    continuing downstream into portions of southern Alabama and
    central/southern Georgia.

    ...Texas...
    Thunderstorm development is possible further south along the front
    and dryline into portions of eastern, central, and southwestern
    Texas. Isolated supercells will be possible with potential for a few
    instances of severe hail and damaging wind. Overall, coverage is
    expected to remain more limited given better forcing for ascent will
    be located to the east.

    ..Thornton/Lyons.. 05/06/2026

    $$

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  • From COD Weather Processor@1:2320/107 to wx-storm@lists.illinois.edu on Wednesday, May 06, 2026 12:44:03
    ACUS01 KWNS 061243
    SWODY1
    SPC AC 061242

    Day 1 Convective Outlook
    NWS Storm Prediction Center Norman OK
    0742 AM CDT Wed May 06 2026

    Valid 061300Z - 071200Z

    ...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS ACROSS PORTIONS
    OF NORTHERN LOUISIANA...CENTRAL MISSISSIPPI...AND CENTRAL ALABAMA...

    ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS THE WESTERN
    TEXAS HILL COUNTRY...

    ...SUMMARY...
    Scattered severe thunderstorms are expected this afternoon and
    evening from eastern Texas into the lower Mississippi and Tennessee Valleys/southern Appalachians. Supercells capable of all hazards
    will be possible across portions of central Mississippi and Alabama
    before a shift to a more of a damaging wind risk into the late evening/overnight.

    ...Synopsis...
    Early-morning satellite imagery shows a pair of phased shortwave
    troughs, one in the northern stream moving southward into UT/CO and
    the other in southern stream off the southern CA/northern Baja
    coast. Strong, confluent flow aloft exists downstream of these
    shortwaves, with an extensive fetch of moderate to strong
    southwesterly flow extending from northern Mexico into the
    Northeast. A general deepening of the upper troughing is anticipated
    throughout the day as the northern-stream shortwave continues
    southeastward while the southern-stream shortwave moves gradually
    eastward. This evolution will result in strengthening mid to upper
    level flow from the southern Plain into New England, particularly
    from the Lower MO Valley through the OH Valley where 500 mb flow
    could exceed 100 kt. This evolution will also push a cold front,
    which currently extends from the TX Hill Country into western PA,
    farther south.

    There will be some displacement between the strongest flow aloft and
    the more warm and moist conditions south of the front. However,
    even with this displacement, moderate to strong upper/mid flow is
    still expected across much of the southern Plains and Southeast.
    Strong to severe thunderstorms are still expected along and ahead of
    this cold front from the TX Hill Country through the Southeast and
    into the Carolinas. Highest coverage of severe thunderstorms will be
    from central MS into central AL, where supercells capable of all
    hazards will be possible.

    ...East TX/Lower MS Valley into the Southeast...
    Recent surface analysis placed the cold front from near JCT in the
    TX Hill Country northeastward through the Arklatex, northern MS, and
    western TN. A weak low exists along this boundary over the western
    AR/LA vicinity. 70s dewpoints extend from south TX across LA into
    far western MS and southern AR, with upper 60s dewpoints through
    much of MS. Low-level moisture advection is expected to continue
    throughout the day, with mid 70s dewpoints possible from central LA
    into central MS by the afternoon. This increasing moisture amid
    filtered daytime heating will result in strong buoyancy ahead of the
    front (i.e. 2500 J/kg of MLCAPE), despite poor mid-level lapse
    rates. Also, as mentioned in the synopsis, strong deep-layer shear
    will be in place, resulting in an overall airmass that supports
    supercells.

    However, whether discrete supercells can develop and mature remains
    uncertain. A combination of neutral height tendencies, widespread
    cloud cover, and warm-air advection initiated storms will likely
    lead to complex convective evolution and related storm interactions.
    Majority of the convection-allowing guidance develops
    thunderstorms within the warm sector from northern LA into central
    MS by 18Z. Thunderstorm development is possible along the front from
    northern AL into northern LA around this time as well. Large to very
    large hail will be the primary risk with these storms, although
    there is also a risk for tornadoes if a storm can remain discrete.
    The tornado risk is expected to increase from the late afternoon
    through the evening from central MS into central AL as low-level
    hodographs lengthen in response to strengthening low-level flow.
    Environmental conditions support the potential for a strong tornado
    during this timeframe. Whether or not storms can realize this
    increasing low-level shear will largely be a function of storm mode.
    Storms should eventually begin to cluster and to grow upscale, with
    an increasing damaging wind threat continuing downstream into
    portions of southern Alabama and central/southern Georgia.

    The front will continue slowly southward, and the very moist
    environment could support additional warm sector storms throughout
    much of the evening and overnight, supporting a continued risk for
    all severe hazards. Several rounds of elevated storms are possible
    as well, with hail as the primary risk with these storms.

    ...TX Hill Country into southeast TX...
    A pair of supercells capable of large hail are currently ongoing
    across southwest TX (Crockett and Sutton Counties). Environmental
    conditions are favorable for storm maintenance for at least an hour
    or two before northward displacement from the better buoyancy leads
    to weakening. Additional isolated development is possible farther
    east into central and southeast TX during the afternoon and evening.
    Any storms that mature would likely be supercellular and capable of
    producing severe hail and damaging wind gusts.

    ..Mosier/Dean.. 05/06/2026

    $$

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  • From COD Weather Processor@1:2320/107 to wx-storm@lists.illinois.edu on Wednesday, May 06, 2026 16:27:05
    ACUS01 KWNS 061627
    SWODY1
    SPC AC 061625

    Day 1 Convective Outlook
    NWS Storm Prediction Center Norman OK
    1125 AM CDT Wed May 06 2026

    Valid 061630Z - 071200Z

    ...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS ACROSS PORTIONS
    OF NORTHEAST LOUISIANA...CENTRAL AND SOUTHERN MISSISSIPPI...AND INTO
    CENTRAL ALABAMA...

    ...SUMMARY...
    Scattered severe thunderstorms are expected this afternoon and
    evening from central Texas into the lower Mississippi and Tennessee Valleys/southern Appalachians. Supercells capable of all hazards
    will be possible across portions of central Mississippi and Alabama
    before a shift to a more of a damaging wind risk into the late evening/overnight.

    ...TX/Lower MS Valley into the Southeast...
    A corridor of strong mid to high-level west-southwesterly flow
    extends from TX into the central and southern Appalachians to the
    southeast of a larger-scale positively tilted trough with embedded
    shortwaves. Morning surface mesoanalysis depicted a cold front
    slowly moving southward across south-central TX through northern MS
    and into the southern Appalachians. South of the boundary, a
    quasi-zonal flow regime with little mid-level height change is
    expected through tonight. A moist airmass maintained by southerly
    flow will yield surface dewpoints ranging from the mid-upper 60s to
    lower to mid 70s deg F south of the front. Despite extensive cloud
    cover owing to the moist boundary layer (reference the 16 g/kg
    lowest 100-mb mean mixing ratios from the 12 UTC Lake Charles and
    Slidell, LA raobs), heating and persistent weak low-level warm
    advection will combine to erode convective inhibition and yield
    scattered storms developing later this afternoon. Moderately steep
    mid-level lapse rates and seasonably rich moisture/PW will support
    strong buoyancy ahead of the front (i.e. 2500 J/kg of MLCAPE) over
    LA/MS. Gradual intensification of storms in the moist environment
    will likely result in several strong supercells eventually
    developing late this afternoon through the evening. Large to very
    large hail, damaging gusts, and tornadoes will be possible with the
    stronger storms. The tornado risk is forecast to peak late this
    afternoon through the evening as southwesterly 850-mb flow
    strengthens from 25 kt to 35-40 kt. Environmental conditions support
    the potential for a strong tornado during this timeframe. Whether
    or not storms can realize this increasing low-level shear will
    largely be a function of storm mode. Storms should eventually begin
    to cluster and to grow upscale, with an increasing damaging wind
    threat continuing downstream into Alabama and Georgia.

    The front will continue slowly southward, and the very moist
    environment could support additional warm sector storms throughout
    much of the evening and overnight, supporting a continued risk for
    all severe hazards, perhaps extending into northern GA and Upstate
    SC late tonight.

    ..Smith/Thompson.. 05/06/2026

    $$

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  • From COD Weather Processor@1:2320/107 to wx-storm@lists.illinois.edu on Wednesday, May 06, 2026 19:50:36
    ACUS01 KWNS 061950
    SWODY1
    SPC AC 061948

    Day 1 Convective Outlook
    NWS Storm Prediction Center Norman OK
    0248 PM CDT Wed May 06 2026

    Valid 062000Z - 071200Z

    ...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS ACROSS SOUTHERN MISSISSIPPI INTO CENTRAL ALABAMA...

    ...SUMMARY...
    Scattered severe thunderstorms are expected this afternoon and
    evening from eastern Texas into the lower Mississippi and Tennessee Valleys/southern Appalachians. Supercells capable of all hazards
    will be possible across portions of central/southern Mississippi and
    central Alabama before a shift to a more of a damaging wind risk
    into the late evening/overnight.

    ...20z Update...
    The primary forecast update was a reduction in severe probabilities
    across portions of central/eastern TX and across the Mid-South in
    the wake of the surface cold front. Latest regional radar mosaic
    shows the early stages of deepening convection across far eastern TX
    into central LA as low-level moisture continues to deepen (per 18z
    RAOBs). This activity is expected to gradually intensify through
    late afternoon amid filtered diurnal heating that should continue to
    erode lingering MLCIN. Strong deep-layer wind shear (sampled in
    regional VWPs and 18 UTC RAOBs) should maintain the severe threat
    through the evening hours. Confidence severe thunderstorms remains
    highest across southern MS where convection originating in central
    LA will likely track and intensify within a favorable environment
    (where STP values will increase to 2-3 by late afternoon) prior to
    undercutting by the cold front later this evening.

    ..Moore.. 05/06/2026

    .PREV DISCUSSION... /ISSUED 1125 AM CDT Wed May 06 2026/

    ...TX/Lower MS Valley into the Southeast...
    A corridor of strong mid to high-level west-southwesterly flow
    extends from TX into the central and southern Appalachians to the
    southeast of a larger-scale positively tilted trough with embedded
    shortwaves. Morning surface mesoanalysis depicted a cold front
    slowly moving southward across south-central TX through northern MS
    and into the southern Appalachians. South of the boundary, a
    quasi-zonal flow regime with little mid-level height change is
    expected through tonight. A moist airmass maintained by southerly
    flow will yield surface dewpoints ranging from the mid-upper 60s to
    lower to mid 70s deg F south of the front. Despite extensive cloud
    cover owing to the moist boundary layer (reference the 16 g/kg
    lowest 100-mb mean mixing ratios from the 12 UTC Lake Charles and
    Slidell, LA raobs), heating and persistent weak low-level warm
    advection will combine to erode convective inhibition and yield
    scattered storms developing later this afternoon. Moderately steep
    mid-level lapse rates and seasonably rich moisture/PW will support
    strong buoyancy ahead of the front (i.e. 2500 J/kg of MLCAPE) over
    LA/MS. Gradual intensification of storms in the moist environment
    will likely result in several strong supercells eventually
    developing late this afternoon through the evening. Large to very
    large hail, damaging gusts, and tornadoes will be possible with the
    stronger storms. The tornado risk is forecast to peak late this
    afternoon through the evening as southwesterly 850-mb flow
    strengthens from 25 kt to 35-40 kt. Environmental conditions support
    the potential for a strong tornado during this timeframe. Whether
    or not storms can realize this increasing low-level shear will
    largely be a function of storm mode. Storms should eventually begin
    to cluster and to grow upscale, with an increasing damaging wind
    threat continuing downstream into Alabama and Georgia.

    The front will continue slowly southward, and the very moist
    environment could support additional warm sector storms throughout
    much of the evening and overnight, supporting a continued risk for
    all severe hazards, perhaps extending into northern GA and Upstate
    SC late tonight.

    $$

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  • From COD Weather Processor@1:2320/107 to wx-storm@lists.illinois.edu on Thursday, May 07, 2026 00:59:37
    ACUS01 KWNS 070059
    SWODY1
    SPC AC 070057

    Day 1 Convective Outlook
    NWS Storm Prediction Center Norman OK
    0757 PM CDT Wed May 06 2026

    Valid 070100Z - 071200Z

    ...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS ACROSS SOUTHERN MISSISSIPPI INTO CENTRAL AND SOUTHERN ALABAMA...

    ...SUMMARY...
    Scattered severe thunderstorms are expected to continue tonight
    across portions of the lower Mississippi Valley into Southeast.
    Supercells ongoing across central and southern parts of Mississippi
    and Alabama into western Georgia will remain capable of all
    severe-weather hazards for the next few hours. Upscale growth into
    storm clusters and/or bowing line segments is expected overnight
    with mainly a damaging wind and isolated tornado risk focused from
    southern Mississippi into central Georgia.

    ...Lower Mississippi Valley into Southeast...

    Early-evening surface analysis placed a convectively augmented cold
    front from northern GA through central MS into the lower Rio Grande
    Valley. The air mass ahead of the front is very moist, characterized
    by dewpoints in the low/mid 70s from LA into MS and AL with MLCAPE
    of 1000-2000 J/kg. Strong deep-layer shear resides across the warm
    sector with effective bulk shear magnitudes of 60-70+ kt. This
    parameter space has supported the development of multiple supercells
    ahead of the front from southern MS into west-central AL, amidst
    additional strong to severe storms. The southern MS supercells have
    a history of producing tornadoes, and based on the 00z LIX sounding
    and regional VWP data, are in a zone of enhanced low-level shear
    with effective SRH of 300-350 m2/2. For additional information on
    these storms, see MCDs 658 and 659.

    Convection-allowing model guidance is suggestive that the ongoing, semi-discrete storms will gradually grow upscale into clusters
    and/or bowing line segments tonight along the southeastward-moving
    cold front, with the most intense storms being focused along the
    low-level jet axis from southern MS through central and southern AL
    into central GA. Damaging winds and isolated tornadoes will become
    the predominant hazards with that storm-mode transition.

    ...Lower Rio Grande Valley...

    Visible satellite indicates multiple attempts at storm initiation
    recently along the high terrain of northwest Mexico, to the
    southwest of Eagle Pass, TX. Convection-allowing model data suggest
    that isolated, strong to severe storms will become increasingly
    possible after about 05z in the same general vicinity with that
    activity potentially crossing the Rio Grande into deep South TX.
    Moderate instability and rather strong deep-layer shear will
    conditionally favor supercell storm modes with a risk for large hail
    and locally damaging wind gusts. A level 1/Marginal Risk will be
    maintained due to uncertainty in storm coverage.

    ..Mead.. 05/07/2026

    $$

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  • From COD Weather Processor@1:2320/107 to wx-storm@lists.illinois.edu on Thursday, May 07, 2026 05:33:40
    ACUS01 KWNS 070533
    SWODY1
    SPC AC 070532

    Day 1 Convective Outlook
    NWS Storm Prediction Center Norman OK
    1232 AM CDT Thu May 07 2026

    Valid 071200Z - 081200Z

    ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS SOUTHEAST
    ALABAMA INTO PORTIONS OF SOUTH GEORGIA AND NORTH FLORIDA...INCLUDING
    THE PANHANDLE...

    ...SUMMARY...
    Widely scattered severe storms capable of damaging winds and a
    couple tornadoes are possible Thursday across southeast Alabama, and
    portions of south Georgia and north Florida, including the
    Panhandle. Isolated strong to severe storms are also possible in
    parts of the Carolinas, as well as the lower Rio Grande Valley and
    deep South Texas.

    ...Synopsis...

    Separate vorticity maxima over the northern Plains and Raton Mesa
    vicinity this evening are forecast to phase while progressing
    through the southern periphery of broader-scale troughing present
    across eastern Canada into the OH Valley and Northeast. That pattern
    evolution will contribute to more substantial height falls from the mid-Atlantic into the southern Appalachians and Southeast on
    Thursday. Strong, mid/upper-level flow will be maintained within the
    base of the deepening trough from the lower-MS Valley into the
    Southeast and mid-Atlantic region.

    At the surface, a cold front is expected to initially stretch from
    the Tidewater region to diffuse low pressure over the western
    Carolinas into northeast GA, and then southwest to the central Gulf
    Coast. That boundary will slowly advance southeast through the day,
    with that feature along with any convective outflow boundaries
    serving as the foci for strong to severe storm development.

    ...Carolinas to northeast Gulf Coast...

    Convection-allowing model guidance suggests that a
    west-to-east-oriented, pre-frontal band of thunderstorms will be
    ongoing at the start of the forecast period (07/12z) across southern
    AL and the FL Panhandle into southern GA, rooted within a
    warm-advection regime along a 40-50 kt low-level jet. The low-level
    jet will aid in the northeastward advection of an increasingly moist
    boundary layer from off the northeast Gulf with dewpoints increasing
    into the low 70s within the inflow region of the early-day storms.
    That moisture will largely contribute to MLCAPE of 500-1000 J/kg,
    despite poor mid-level lapse rates.

    The presence of the low-level jet will support initially strong
    near-ground shear (i.e., effective SRH of 200-300 m2/s2) within the
    instability axis preceding the storms. However, that feature is
    forecast to gradually weaken while migrating east through the
    morning, with seemingly the best tornado potential existing during
    the first few hours of the forecast period. Otherwise, damaging wind
    gusts will be the primary hazard as storms progress southeast
    through the level 2/Slight Risk area.

    Farther to the northeast across the NC/SC Piedmont and Coastal
    Plain, poor lapse rates are expected to limit instability to
    generally less than 500 j/kg. However, deep-layer wind fields will
    be strong, suggesting the potential for locally strong wind gusts
    with any deeper convective elements forming along and ahead of the
    cold front from late morning into afternoon.


    ...Lower Rio Grande Valley/deep South Texas...

    There is a model signal for at least isolated thunderstorm
    development at the start of the forecast period (07/12z) with the
    location of the storms varying from model to model. RAP-based
    soundings suggest that the storms would be slightly elevated above a
    stable, near-surface layer within a moderately unstable environment
    with MUCAPE up to 1000-1500 J/kg. While mid-level lapse rates aren't
    expected to be particularly steep, the presence of 50-60+ kt
    effective bulk shear magnitudes would support the potential for
    supercell structures capable of isolated occurrences of large hail
    and locally damaging wind gusts. The severe-weather threat is expect
    to remain confined to the morning hours.

    ..Mead/Lyons.. 05/07/2026

    $$

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  • From COD Weather Processor@1:2320/107 to wx-storm@lists.illinois.edu on Thursday, May 07, 2026 12:51:42
    ACUS01 KWNS 071251
    SWODY1
    SPC AC 071249

    Day 1 Convective Outlook
    NWS Storm Prediction Center Norman OK
    0749 AM CDT Thu May 07 2026

    Valid 071300Z - 081200Z

    ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS SOUTHEAST
    ALABAMA INTO PORTIONS OF SOUTH GEORGIA AND NORTHERN
    FLORIDA...INCLUDING THE FLORDIA PANHANDLE...

    ...SUMMARY...
    Widely scattered severe storms capable of damaging winds and a
    couple tornadoes are possible today across southeast Alabama, and
    portions of south Georgia and north Florida, including the
    Panhandle. Isolated strong to severe storms are also possible in
    parts of the Carolinas, as well as the lower Rio Grande Valley and
    Deep South Texas.

    ...Southern AL/Southern GA/FL Panhandle into northern FL...
    Regional radar imagery shows showers and thunderstorms ongoing from
    far eastern LA northeastward into southern GA. These storms are
    occurring along and ahead of a cold front that extends from a
    surface low over northwest GA southwestward into the western Gulf.
    The environment preceding this front is moist, modestly buoyant, and
    strongly sheared (i.e. 50 to 70 kt of 0-6 km bulk shear). These
    conditions are supporting occasional intensification of the updrafts
    embedded within the predominately linear structures.

    This trend is forecast to continue for at least the next few hours
    before the stronger low-level flow (which currently extends from the
    western FL Panhandle/southern AL through southern GA) gradually
    shifts northeastward. As such, the greatest tornado potential will
    exist during the first few hours of the forecast period. Otherwise,
    damaging wind gusts will be the primary hazard as storms progress
    southeast through the central/western FL Panhandle and northern FL.

    ...Carolinas...
    Buoyancy is expected to be lower here than areas farther southwest,
    with poor lapse rates expected to limit instability to generally
    less than 500 j/kg. The surface low over northwest GA is forecast to
    shift northeastward throughout the day, with low to mid-level wind
    fields strengthening at the same time. Ascent near the low and
    associated front coupled with the modest buoyancy will result in
    occasionally deeper convective elements along and ahead of the cold
    front from late morning into afternoon. Robust deep-layer wind
    fields across the region will support the potential for damaging
    gusts with any deeper, more persistent updrafts.

    ...Lower Rio Grande Valley/South TX...
    A few isolated thunderstorms have developed east of Del Rio where
    steep mid-level lapse rates are supporting elevated buoyancy atop a
    stable boundary layer (as observed on the 12Z DRT sounding). This
    elevated buoyancy will likely persist throughout the day, combining
    with strong deep-layer vertical shear (i.e. effective bulk shear
    from 50 to 60 kt) to support the potential for supercell structures
    capable of isolated large hail and locally damaging wind gusts.
    Additionally, there is a low-probability chance for a few storms
    farther south into the Lower RGV this evening, where the environment
    remains supportive of large hail.

    ..Mosier/Dean.. 05/07/2026

    $$

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  • From COD Weather Processor@1:2320/107 to wx-storm@lists.illinois.edu on Thursday, May 07, 2026 16:22:12
    ACUS01 KWNS 071622
    SWODY1
    SPC AC 071620

    Day 1 Convective Outlook
    NWS Storm Prediction Center Norman OK
    1120 AM CDT Thu May 07 2026

    Valid 071630Z - 081200Z

    ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FOR THE FLORIDA
    PANHANDLE INTO NORTH FLORIDA AND FAR SOUTHERN GEORGIA...

    ...SUMMARY...
    Widely scattered severe storms capable of damaging winds and a brief
    tornado are possible through the mid afternoon across the Florida
    Panhandle into north Florida and far southern Georgia. Isolated
    strong to severe storms are also possible in parts of the Carolinas,
    as well as south-central Texas.

    ...FL Panhandle into north FL and far southern GA...
    A mid-level vorticity lobe over the Mid South is forecast to rapidly
    move east and reach the NC Outer Banks by mid evening. Late morning satellite/radar imagery shows a broken band of strong to severe
    thunderstorms ahead of a cold front and draped west-southwest to east-northeast. A moist and fully modified boundary layer extends
    from the northeast Gulf into the FL Panhandle and Big Bend with
    notably drier air over interior north FL. Convergence along the
    front is forecast to weaken late today into tonight as a weak low
    over the Carolinas shifts offshore. However, the prefrontal airmass
    will remain moist, moderately unstable, and strongly sheared (50+ kt
    effective shear) across the FL Panhandle vicinity through the mid
    afternoon. Embedded cells within the bands will potentially be
    capable of wind damage and perhaps a brief tornado before this
    activity gradually weakens as it moves into a less-buoyant regime
    farther east of north FL.

    ...Carolinas...
    Some thinning of cloud cover and modest heating ahead of the cold
    front will yield weak buoyancy prior to the front clearing the coast
    later today. Weak low-level lapse rates will tend to limit the
    overall severe risk (i.e., localized wind damage potential).
    However, will maintain low wind probabilities this outlook update
    due to the possibility for a couple of deeper updrafts to organize
    within a region with strong deep-layer wind fields.

    ...Edwards Plateau into the Lower Rio Grande Valley...
    Elevated buoyancy will likely persist throughout the day with a few
    stronger updrafts intermittently developing over the Hill Country
    and Edwards Plateau. Strong deep-layer vertical shear (i.e.
    effective bulk shear from 50 to 60 kt) and 1000+ J/kg MUCAPE may
    support the potential for an isolated risk for marginally severe
    hail. Farther south and displaced away from the higher terrain,
    very low thunderstorm coverage is expected despite a modifying and
    more moist airmass. Have trimmed hail probabilities over this
    region due to the lack of storm coverage in the latest model
    guidance.

    ..Smith/Chalmers.. 05/07/2026

    $$

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  • From COD Weather Processor@1:2320/107 to wx-storm@lists.illinois.edu on Thursday, May 07, 2026 19:50:13
    ACUS01 KWNS 071950
    SWODY1
    SPC AC 071948

    Day 1 Convective Outlook
    NWS Storm Prediction Center Norman OK
    0248 PM CDT Thu May 07 2026

    Valid 072000Z - 081200Z

    ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS NORTHERN FLORIDA
    INTO GEORGIA AND THE CAROLINAS...

    ...SUMMARY...
    Isolated strong to severe storms will remain possible across
    portions of northern Florida into Georgia and parts of the
    Carolinas.

    ...20z Update...
    MRMS VIL has depicted a weakening trend in convection across the FL
    Panhandle and northern FL over the past 1-2 hours as convection
    migrates east into a more deeply mixed/drier air mass. A downstream
    18 UTC sounding from JAX sampled diminished mid-level lapse rates
    and increased inhibition as well, casting doubt on the potential for re-intensification across north FL through the afternoon. For this
    reason, 15% wind and 5% tornado risk probabilities were removed,
    though recent high-res guidance suggests that a strong storm or two
    will remain possible as the surface cold front continues to push
    southeast through early evening. Further northeast into GA and the
    Carolinas, gradual clearing has allowed temperatures to warm into
    the low to mid 70s amid low/mid 60s dewpoints. This is supporting
    modest MLCAPE values (500 J/kg or less) within an otherwise strongly
    sheared environment. Given these trends, opted to maintain low-end
    wind probabilities to account for isolated strong convection capable
    of damaging winds.

    Across southern/central TX, elevated convection has shown a similar
    weakening trend over the past few hours. While transient stronger
    updrafts will remain possible given residual MUCAPE sampled by
    regional ACARS soundings, the recent convective trends coupled with
    nebulous forcing for ascent and minimal updraft/UH signal in recent
    CAM guidance lends enough confidence to remove 5% hail
    probabilities.

    ..Moore.. 05/07/2026

    .PREV DISCUSSION... /ISSUED 1120 AM CDT Thu May 07 2026/

    ...FL Panhandle into north FL and far southern GA...
    A mid-level vorticity lobe over the Mid South is forecast to rapidly
    move east and reach the NC Outer Banks by mid evening. Late morning satellite/radar imagery shows a broken band of strong to severe
    thunderstorms ahead of a cold front and draped west-southwest to east-northeast. A moist and fully modified boundary layer extends
    from the northeast Gulf into the FL Panhandle and Big Bend with
    notably drier air over interior north FL. Convergence along the
    front is forecast to weaken late today into tonight as a weak low
    over the Carolinas shifts offshore. However, the prefrontal airmass
    will remain moist, moderately unstable, and strongly sheared (50+ kt
    effective shear) across the FL Panhandle vicinity through the mid
    afternoon. Embedded cells within the bands will potentially be
    capable of wind damage and perhaps a brief tornado before this
    activity gradually weakens as it moves into a less-buoyant regime
    farther east of north FL.

    ...Carolinas...
    Some thinning of cloud cover and modest heating ahead of the cold
    front will yield weak buoyancy prior to the front clearing the coast
    later today. Weak low-level lapse rates will tend to limit the
    overall severe risk (i.e., localized wind damage potential).
    However, will maintain low wind probabilities this outlook update
    due to the possibility for a couple of deeper updrafts to organize
    within a region with strong deep-layer wind fields.

    ...Edwards Plateau into the Lower Rio Grande Valley...
    Elevated buoyancy will likely persist throughout the day with a few
    stronger updrafts intermittently developing over the Hill Country
    and Edwards Plateau. Strong deep-layer vertical shear (i.e.
    effective bulk shear from 50 to 60 kt) and 1000+ J/kg MUCAPE may
    support the potential for an isolated risk for marginally severe
    hail. Farther south and displaced away from the higher terrain,
    very low thunderstorm coverage is expected despite a modifying and
    more moist airmass. Have trimmed hail probabilities over this
    region due to the lack of storm coverage in the latest model
    guidance.

    $$

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  • From COD Weather Processor@1:2320/107 to wx-storm@lists.illinois.edu on Friday, May 08, 2026 00:36:44
    ACUS01 KWNS 080036
    SWODY1
    SPC AC 080035

    Day 1 Convective Outlook
    NWS Storm Prediction Center Norman OK
    0735 PM CDT Thu May 07 2026

    Valid 080100Z - 081200Z

    ...NO SEVERE THUNDERSTORM AREAS FORECAST...

    ...SUMMARY...
    Severe storms are not expected through tonight.

    ...MT/WY...

    Forcing for ascent attendant to a short-wave trough moving southeast
    through the region has fostered widely scattered thunderstorms from
    portions of northwest MT into central WY as of 00z. Moisture is
    limited, but the presence of steep lapse rates (ref. 00z RIW
    sounding) may be sufficient to support briefly strong storms capable
    of gusty winds and/or small hail for the next couple of hours.

    ...Carolinas...

    A small cluster of showers and thunderstorms is ongoing across parts
    of southern and central NC along a cold front settling south through
    the area. Weakening, low-level lapse rates and resultant instability
    should limit any severe-weather threat as the convection continues
    east tonight.

    ...LA...

    A few thunderstorms have recently developed in the vicinity of the
    surface front in far southeast LA amidst a moist low-level air mass.
    The 00z LIX sounding located to the immediate north of the front
    sampled MUCAPE of around 1500 J/kg for parcels lifted from around 1
    KM. Moreover, deep-layer shear remains strong (effective bulk shear
    of 60 kt), which would conditionally support some storm
    organization. Current thinking is that nebulous forcing for ascent
    and poor low/mid-level lapse rates will tend to limit updraft vigor
    in an otherwise seemingly favorable, severe-storm environment. As
    such, no severe-weather probabilities will be included for this
    forecast.

    ...Southern AZ/NM into TX...

    Isolated thunderstorms remain possible overnight from southern parts
    of AZ and NM into western and southern TX, near and ahead of a
    mid-level low drifting east across Sonora and Chihuahua, Mexico.

    ..Mead.. 05/08/2026

    $$

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  • From COD Weather Processor@1:2320/107 to wx-storm@lists.illinois.edu on Friday, May 08, 2026 05:44:17
    ACUS01 KWNS 080544
    SWODY1
    SPC AC 080542

    Day 1 Convective Outlook
    NWS Storm Prediction Center Norman OK
    1242 AM CDT Fri May 08 2026

    Valid 081200Z - 091200Z

    ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FROM SOUTHEAST
    KANSAS THROUGH MUCH OF CENTRAL AND EASTERN OKLAHOMA INTO NORTH
    TEXAS...

    ...SUMMARY...
    Scattered severe storms capable of large hail and damaging winds are
    possible from southeast Kansas through much of central and eastern
    Oklahoma into north Texas Friday afternoon into Friday night. More
    sparse occurrences of large hail and damaging winds are possible
    across the Ozarks, central and south TX, and the Gulf Coast states.

    ...Synopsis...

    An 80-90 kt upper-level jet streak located across the northern
    Rockies this evening will progress southeast into the central Plains
    on Friday, contributing to amplification of a short-wave trough over
    the same general area. That disturbance is then expected to weaken
    Friday night as it moves into an increasingly confluent, mid-level
    flow regime in place across the lower OH and TN Valleys. Elsewhere,
    a mid/upper-level low over Sonora into Chihuahua, Mexico at the
    start of the period is forecast to evolve into a weakening, open
    wave while accelerating east through TX into the lower-MS Valley.

    At the surface, a cold front associated with the northern-stream,
    short-wave trough will progress south through the central into
    southern High Plains on Friday with the boundary extending from the
    southern TX Panhandle through n-central OK and southeast KS into
    central MO by mid/late afternoon. A diffuse dryline or pre-frontal
    trough will extend from southwest TX into the southeast TX
    Panhandle, where it will link with the cold front.

    Elsewhere, a cold front currently advancing south through the
    Carolinas and GA is expected continue its slow, southward movement
    into the northern FL Peninsula by afternoon. However, the western
    extension of the front initially over the northwest Gulf is forecast
    to weaken or lift north as a warm front into TX and LA on Friday,
    allowing a moist, unstable air mass to those areas. The front is
    expected to move onto the central and northeast Gulf Coast Friday
    night as the low-level mass field responds to the short-wave trough
    moving into the TN Valley.


    ...Oklahoma and north Texas into the Ozarks...

    Modest, boundary-layer moistening is anticipated on Friday ahead of
    the cold front with dewpoints increasing into the low/mid 50s. That
    process will occur beneath the eastern extension of a steep,
    mid-level lapse rate (EML) plume, supporting MLCAPE up to 1000-1500
    J/kg from OK into southeast KS. Greater cloud cover and the
    potential for early-day showers and storms are expected to limit the destabilization process farther northeast along the front into the
    Ozarks.

    Increased height falls/forcing for ascent attending the migratory
    short-wave trough coupled with convergence along the cold front are
    expected to foster scattered thunderstorm development by early
    afternoon across portions of northern into central MO with
    subsequent southwestward development along the boundary across
    southeast KS into northern OK by mid/late afternoon.

    Isolated occurrences of damaging wind and hail are possible along
    and ahead of the MO segment of the front, where 40-45 kt of
    effective bulk shear will coincide with MLCAPE of generally less
    than 1000 J/kg. Across the level 2/Slight Risk area, comparatively
    steeper lapse rates and resultant greater instability are expected
    to offer a higher probability of supercell storm modes with the
    initial hazard being large hail up to 2" in diameter. A deeper,
    well-mixed boundary with sizable temperature-dewpoint spreads is
    expected to limit tornado potential, especially given modest
    low-level shear. The models do hint at some increase in low-level
    shear toward 00z across northeast Ok into southeast KS, where some
    tornado risk could evolve. Otherwise, there is a consistent signal
    across a number of convection-allowing models that the initial
    storms will grow upscale into a forward-propagating QLCS that tracks
    south through central and southern OK into at least north TX Friday
    evening into Friday night. A transition to more of a damaging wind
    threat is expected with that storm-mode evolution.


    ...East Texas to north Florida...

    Late-evening water vapor imagery indicates a vorticity lobe pivoting
    through the southeastern periphery of the northern Mexico upper low.
    That disturbance is expected to progress into south-central TX
    Friday morning, with a downstream belt of low-level warm advection
    fostering scattered storms from late morning through the afternoon
    from the upper TX coast to north FL. Additional storms may also
    develop from the vicinity of the front south along the east-coast
    sea breeze in the northeast FL Peninsula.

    Much of the thunderstorm activity from the upper TX coast into
    southern parts of LA, MS, and AL is likely to be slightly elevated
    to the north of the stalled front off the coast. RAP and NAM-based
    forecast soundings indicate the presence of a moist environment with
    MUCAPE of 1000-1500 J/kg. However, mid-level lapse rates are
    expected to be weak, which may tend to limit updraft strength and
    storm organization, despite the presence of 40-50 kt effective bulk
    shear. As such, a level 1/Marginal Risk has been maintained with the expectation of isolated occurrences of large hail and/or locally
    damaging wind gusts. A brief tornado cannot be ruled out with any
    storms closer to the coast, which could become rooted in a moist and
    modestly sheared boundary layer.

    Farther to the east across north FL, afternoon storms are expected
    to be surface-based in the vicinity of the front and east-coast sea
    breeze. Model soundings depict a very moist environment with tall,
    relatively skinny CAPE profiles with 1000-1500 J/kg of MLCAPE. The
    presence of 50-60 kt of effective bulk shear will be more than
    sufficient to support some supercell structures capable of hail and
    locally damaging wind gusts.

    An additional round of mainly elevated thunderstorms appears
    possible Friday night across portions of the lower-MS Valley with an
    attendant risk for isolated, large hail and/or locally strong wind
    gusts.

    ...South-central Texas...

    Forcing for ascent associated with the lead vorticity maximum
    mentioned in the previous section may contribute to the development
    of isolated to widely scattered thunderstorms from the mid/lower Rio
    Grande Valley into south-central TX from late morning into
    afternoon. However, relatively strong capping evident in RAP-based
    soundings cast uncertainty on eventual storm coverage, and as such,
    a level 1/Marginal Risk will be maintained. The overall environment
    will support supercell storm modes with an attendant risk for large
    to very large hail and locally strong wind gusts, given storm
    initiation and sustenance.

    ..Mead/Halbert.. 05/08/2026

    $$

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  • From COD Weather Processor@1:2320/107 to wx-storm@lists.illinois.edu on Friday, May 08, 2026 12:30:50
    ACUS01 KWNS 081230
    SWODY1
    SPC AC 081228

    Day 1 Convective Outlook
    NWS Storm Prediction Center Norman OK
    0728 AM CDT Fri May 08 2026

    Valid 081300Z - 091200Z

    ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS MUCH OF
    OKLAHOMA...

    ...SUMMARY...
    Scattered severe storms capable of large hail and damaging winds are
    possible from southeast Kansas through much of central and eastern
    Oklahoma into north Texas Friday afternoon into Friday night. More
    sparse occurrences of large hail and damaging winds are possible
    across the Ozarks, central and south TX, and the Gulf Coast states.

    ...Central Plains...
    Morning water vapor imagery shows a shortwave trough over western KS
    tracking southeastward. Full sunshine will lead to strong heating/destabilization ahead of the associated cold front over
    eastern KS and much of OK. Dewpoints in the 50s, coupled with steep
    low/mid level lapse rates will yield afternoon MLCAPE values of
    1000-1500 J/kg and the development of scattered thunderstorms along
    the front. These storms will track southeastward through the
    evening across much of OK and into north TX. Forecast soundings
    indicate favorable vertical shear profiles for supercell structures
    capable of large hail.

    Eventual upscale organization into linear/bowing structures will aid
    in a risk of damaging winds as storms persist into the overnight
    period across the ArkLaTex. While the overall severe threat should
    diminish by this time, storms may occasionally result in damaging
    wind gusts and hail.

    ...Central Gulf Coast...
    Clusters of showers and thunderstorms are ongoing this morning
    along/north of a surface boundary that extends from southeast TX
    along the Gulf Coast into north FL. Storms are expected to increase
    in coverage during the afternoon along the front, with a few strong
    to severe cells expected. Gusty winds are the primary concern.

    ..Hart/Wendt.. 05/08/2026

    $$

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  • From COD Weather Processor@1:2320/107 to wx-storm@lists.illinois.edu on Friday, May 08, 2026 16:27:50
    ACUS01 KWNS 081627
    SWODY1
    SPC AC 081626

    Day 1 Convective Outlook
    NWS Storm Prediction Center Norman OK
    1126 AM CDT Fri May 08 2026

    Valid 081630Z - 091200Z

    ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS MUCH OF
    OKLAHOMA...

    ...SUMMARY...
    Scattered severe storms capable of large hail and severe gusts are
    possible from southeast Kansas through much of central and eastern
    Oklahoma into north Texas this afternoon into tonight. More sparse
    occurrences of large hail and damaging winds are possible across the
    Ozarks, central and south Texas, and the Gulf Coast states.

    ...Central Plains...
    Visible-satellite imagery late this morning shows the northern
    periphery of stratus and stratocumulus across southwest OK and a
    more extensive stratus field over central and north TX. These
    clouds generally coincide with surface observations and GPS PW of
    richer moisture returning northward ahead of a mid-level shortwave
    trough over western KS that is forecast to move southeastward into
    southeast KS and OK by early evening. Strong heating ahead of a southeastward-moving cold front and 50s dewpoints will yield MLCAPE
    1000-1500 J/kg by mid afternoon. Model guidance continues to
    indicate initial cellular activity evolving into a band of storms
    along the front and pushing south-southeast this evening. Forecast
    soundings will support supercells early before coalescing cold pools
    promote upscale growth into a linear cluster. Supercell development
    will subsequently favor anchoring updrafts on the southwest extent
    of the developing convection. Severe gusts along with some
    lingering hail risk will probably continue into the late evening and
    overnight but diminish in overall magnitude/coverage of severe as
    this activity moves into north TX and the Arklatex.

    ...Central Gulf Coast...
    Clusters of showers and thunderstorms are ongoing this morning
    along/north of a surface boundary that extends from southeast TX
    along the Gulf Coast into north FL. Storms are expected to increase
    in coverage during the afternoon along the front, with a few strong
    to severe cells expected. A mix of hail/wind will be possible with
    the stronger thunderstorms.

    ..Smith/Chalmers.. 05/08/2026

    $$

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  • From COD Weather Processor@1:2320/107 to wx-storm@lists.illinois.edu on Friday, May 08, 2026 20:00:54
    ACUS01 KWNS 082000
    SWODY1
    SPC AC 081959

    Day 1 Convective Outlook
    NWS Storm Prediction Center Norman OK
    0259 PM CDT Fri May 08 2026

    Valid 082000Z - 091200Z

    ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS NORTH TEXAS INTO
    OKLAHOMA AND FAR SOUTHEAST KANSAS...

    ...SUMMARY...
    Scattered severe storms capable of large hail and severe gusts are
    possible from southeast Kansas through much of central and eastern
    Oklahoma into north Texas this afternoon into tonight. More sparse
    occurrences of large hail and damaging winds are possible across the
    Ozarks, central and south Texas, and the Gulf Coast states.

    ...20z Update...
    The forecast largely remains on track with only minor adjustments
    made based on recent convective trends and latest high-res guidance.


    ...Northern FL and southern AL/GA...
    5% wind and hail probabilities were both expanded across the FL Panhandle/northern FL into adjacent portions of southern AL and GA
    ahead of a persistent strong thunderstorms. This cell has shown
    signs of period intensification to severe levels, and a downstream
    18z JAX sounding sampled adequate buoyancy within a MUCAPE gradient
    for storm maintenance, as well as very strong (57 knot) effective
    bulk shear that may support additional periods of intensification
    through late afternoon (see MCD #671 for additional details).

    ...Southern MS/AL...
    Minor expansions of the 5% hail/wind contours were made across
    portions of southern MS and southwest AL. Elevated convection
    developing across northern LA will likely spread east/southeast
    during the 09-12 UTC period, and may pose a risk of large hail and
    perhaps damaging gusts. While clustered storm modes will likely
    modulate the overall severe threat, sufficient MUCAPE and deep-layer
    wind shear should be in place to support a few stronger cells.

    ...Oklahoma...
    The early stages of convective initiation are well underway across north-central OK with a more expansive cumulus field noted across
    northwest OK ahead of a cold front (see MCD # 670 for additional
    short-term details). Recent high-res solutions (notably recent runs
    of the HRRR) compare reasonably well these convective trends and to
    a recent 19 UTC OUN RAOB. This lends reasonably high confidence in
    the evolution of the severe hail and wind threat across central to north/northeast OK through mid-evening. Although the greatest severe
    risk will likely materialize along and north of the I-44 corridor
    over the next several hours, the somewhat marginal thermodynamic
    environment and widely scattered convective signal in guidance
    sufficiently limited confidence for higher risk (namely 30% hail) probabilities. However, slight expansions of the 5% and Intensity
    Level 1 hail contours were made to account for recent observed
    trends.

    ..Moore.. 05/08/2026

    .PREV DISCUSSION... /ISSUED 1126 AM CDT Fri May 08 2026/

    ...Central Plains...
    Visible-satellite imagery late this morning shows the northern
    periphery of stratus and stratocumulus across southwest OK and a
    more extensive stratus field over central and north TX. These
    clouds generally coincide with surface observations and GPS PW of
    richer moisture returning northward ahead of a mid-level shortwave
    trough over western KS that is forecast to move southeastward into
    southeast KS and OK by early evening. Strong heating ahead of a southeastward-moving cold front and 50s dewpoints will yield MLCAPE
    1000-1500 J/kg by mid afternoon. Model guidance continues to
    indicate initial cellular activity evolving into a band of storms
    along the front and pushing south-southeast this evening. Forecast
    soundings will support supercells early before coalescing cold pools
    promote upscale growth into a linear cluster. Supercell development
    will subsequently favor anchoring updrafts on the southwest extent
    of the developing convection. Severe gusts along with some
    lingering hail risk will probably continue into the late evening and
    overnight but diminish in overall magnitude/coverage of severe as
    this activity moves into north TX and the Arklatex.

    ...Central Gulf Coast...
    Clusters of showers and thunderstorms are ongoing this morning
    along/north of a surface boundary that extends from southeast TX
    along the Gulf Coast into north FL. Storms are expected to increase
    in coverage during the afternoon along the front, with a few strong
    to severe cells expected. A mix of hail/wind will be possible with
    the stronger thunderstorms.

    $$

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  • From COD Weather Processor@1:2320/107 to wx-storm@lists.illinois.edu on Saturday, May 09, 2026 00:54:55
    ACUS01 KWNS 090054
    SWODY1
    SPC AC 090053

    Day 1 Convective Outlook
    NWS Storm Prediction Center Norman OK
    0753 PM CDT Fri May 08 2026

    Valid 090100Z - 091200Z

    ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS IN SOUTHERN AND
    EASTERN OK INTO NORTH TEXAS...

    ...SUMMARY...
    Scattered severe storms capable of large hail and severe gusts are
    expected to continue this evening into tonight across southern and
    eastern Oklahoma into north Texas. Isolated occurrences of large
    hail and damaging winds are possible across the Ozarks, south Texas,
    and the ArkLaTex across the Gulf Coast states.

    ...OK into north TX...

    As of 0030z, three distinct clusters of severe storms (with embedded
    supercell structures) are ongoing near and to the south of I-44 in
    OK, with recent reports of hail up to 2.50-2.75". The 00z OUN
    sounding sampled the inflow air mass to the ongoing storms with
    steep low/mid-level lapse rates supporting moderate instability with
    around 50 kt of deep-layer shear. The ongoing storms are expected to
    continue southeast, with a sub-set of the current activity
    potentially moving into north TX by 03z. Large hail will remain the
    predominant hazard, with the damaging wind threat being more
    conditional on the development of an organized cold pool. For
    additional, short-term guidance, see the recently issued MCD 675.


    ...ArkLaTex to north Florida...

    As of 00z, widely scattered thunderstorms are ongoing across far
    south GA and north FL in the vicinity of a stalled front. The air
    mass to the south of the front remains moderately unstable with
    estimated MLCAPE of 1000-2000 J/kg. The current KJAX VWP is sampling
    around 50 kt of effective bulk shear, which coupled with the
    instability will remain supportive of locally strong wind gusts and
    perhaps some marginally severe hail for the next couple of hours.

    Elsewhere, isolated storms are ongoing across parts of the Sabine
    River Valley, aided by a low-level warm advection regime, per
    regional VWPs. Short-term model guidance suggests that storms will
    increase in areal coverage over the next several hours in the
    ArkLaTex vicinity as the region is glanced by a short-wave trough
    passing to the immediate north. Gradual upscale growth into a forward-propagating QLCS appears possible, with the system moving
    into central and southern parts of LA and MS by 12z Saturday.
    Initial storms are likely to be somewhat elevated. However, with
    time the storms may become more progressively rooted within a
    moistening boundary layer returning north through the region.
    Generally weak lapse rates are expected to limit severe-weather
    coverage and intensity, with isolated occurrences of large hail and
    damaging winds appearing possible.


    ...South TX...

    A short-wave trough over southwest TX into Chihuahua, Mexico this
    evening will continue east tonight with downstream height
    falls/forcing for ascent progressively overspreading south TX.
    Visible satellite and mosaic radar data indicate gradually
    increasing convection across the high terrain of northeast Mexico,
    and there is some signal in model guidance that isolated storms
    could cross the Rio Grande into south TX overnight. The 00z DRT
    sounding sampled a fairly strong cap centered around 1.5 km AGL,
    which may initially prohibit storm development. With time, dynamic
    cooling aloft may be sufficient for isolated storms to move into the
    region with an attendant large hail and damaging wind threat.

    ..Mead.. 05/09/2026

    $$

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  • From COD Weather Processor@1:2320/107 to wx-storm@lists.illinois.edu on Saturday, May 09, 2026 05:41:27
    ACUS01 KWNS 090541
    SWODY1
    SPC AC 090539

    Day 1 Convective Outlook
    NWS Storm Prediction Center Norman OK
    1239 AM CDT Sat May 09 2026

    Valid 091200Z - 101200Z

    ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS IN WESTERN AND
    CENTRAL OKLAHOMA INTO NORTHWEST TEXAS...

    ...SUMMARY...
    Widely scattered severe thunderstorms capable of large to very large
    hail, locally damaging wind gusts, and perhaps a few tornadoes are
    possible in parts of western into central Oklahoma Saturday
    afternoon and evening. Sparser large hail and damaging wind
    occurrences are possible across the Gulf Coast states, the northern
    and central High Plains, the Great Lakes, and possibly mid-Atlantic.

    ...Synopsis...

    A broad, cyclonic flow regime is forecast across much of the CONUS
    east of the Rockies through the forecast period. A number of
    embedded vorticity maxima moving through that large-scale pattern
    will potentially aid in strong to severe storm development. The
    first of which will track from the northern Rockies into the central
    High Plains by Saturday evening. A stronger disturbance will be
    attended by mid/upper-level jet streaks while progressing through
    the Great Lakes region on Saturday. Additional, weaker disturbances
    will traverse the Gulf Coast states and mid-Atlantic region.

    At the surface, a cold front associated with the Great Lakes
    disturbance will sweep east across that region during the day with
    the trailing extension of the front advancing south into central
    High Plains. An area of low pressure is forecast to develop along
    the front in northwest KS Saturday afternoon with a pre-frontal
    trough/dryline extending south from the low through the eastern
    OK/TX Panhandles into west-central TX. Elsewhere, a front stretching
    from south TX through the shelf waters of the northern Gulf into
    north FL as of late evening will attempt to lift north as a warm
    front. The advance of the boundary across the central and eastern
    Gulf Coast may be impeded by early-day thunderstorms moving through
    those areas.


    ...Western and Central Oklahoma into Northwest Texas...

    The cold front that has pushed into the southern Plains this evening
    is expected to wash out with initially modest moisture return
    expected ahead of the trough/dryline with dewpoints increasing
    through the 50s Saturday afternoon over the far eastern OK/TX
    Panhandles into western OK. The moisture increase combined with
    steep low/mid-level lapse rates will support an initially narrow
    axis of 1000-1500 J/kg MLCAPE by mid/late afternoon.

    While large-scale forcing for ascent will remain negligible through
    the peak of the diurnal heating cycle, strong heating west of the
    dryline and resultant deepening circulations along it are expected
    to yield isolated to widely scattered, high-based storms by late
    afternoon into early evening. 40-50 kt of effective bulk shear will
    support supercell storm modes with large to very large hail being
    the predominant hazard.

    Considerable strengthening of the low-level jet is forecast across
    western and central OK Saturday evening, which will enhance
    low-level shear and the influx of greater, boundary-layer moisture
    content. There is some model variability in the degree of evening
    moistening that occurs, with the RAP remaining notably drier than
    the NAM. Should the NAM scenario be closer to correct, tornado
    potential would increase during the evening with any sustained
    supercells from western into central OK. An 5% unconditional
    probability and conditional-intensity group 1 have been added to
    account for that possibility.


    ...Gulf Coast...

    Clusters of thunderstorms or a quasi-linear MCS is expected to be
    ongoing at 12z Saturday over the lower MS Valley, aided by a
    low-level warm/moist advection regime. Forecast soundings suggest
    that activity may be slightly elevated atop a shallow, near-surface
    inversion and rooted within a moist environment with MUCAPE upwards
    of 1500 J/kg. The 00z convection-allowing models suggest that
    activity will continue south/southeast and potentially become more surface-based across the central and eastern Gulf Coast from late
    morning into afternoon. Generally weak low/mid-level lapse rates are
    expected to limit updraft intensity, despite the presence of 40-50
    kt effective bulk shear. Nonetheless, the potential will exist for
    marginally severe hail and locally strong to severe wind gusts,
    especially if a cold pool can organize.


    ...Great Lakes...

    The pre-frontal air mass is not expected to be overly moist on
    Saturday with dewpoints largely in the upper 40s to low 50s.
    However, steepening low/mid-level lapse rates are expected to yield
    a modestly unstable air mass by afternoon with MLCAPE of around 500
    J/kg. The destabilization process will coincide with gradually
    veering low-level winds, which will tend to limit the magnitude of
    low-level and deep-layer shear.

    Forcing for ascent associated with the short-wave trough mentioned
    in the synopsis coupled with convergence/lift along the front are
    expected to foster a broken band of thunderstorms initially across
    eastern lower MI by early afternoon. Additional storms are expected
    to form farther south along the front in northern OH with the
    convective band rapidly moving east into portions of western NY and
    northwest PA by late afternoon or early evening. Cold temperatures
    aloft will favor isolated occurrences of marginally severe hail.
    Locally strong wind gusts will also be possible during the afternoon
    and early evening hours.


    ...Central Wyoming into southwest Nebraska and Northwest Kansas...

    Increasing height falls/forcing for ascent preceding the short-wave
    trough moving out of the northern Rockies will overspread a
    steep-lapse-rate, but limited-moisture environment Saturday
    afternoon, fostering the development of widely scattered, high-based
    storms. The presence of 30-40 kt of effective bulk shear will
    support some storm organization with the potential for isolated
    occurrences of large hail and locally damaging winds during the
    afternoon and evening hours.


    ...Mid-Atlantic States...

    A couple weak disturbances traversing the lower Great Lakes and
    central Appalachians are expected to contribute an area of showers
    across portions of PA and southern NY into New England Saturday
    morning into early afternoon. Weak destabilization on the southern
    fringe of that cloud canopy may support isolated thunderstorm
    development during the afternoon from the DE River Valley into parts
    of MD amidst a weakly unstable environment with MLCAPE of only a few
    hundred J/kg. Both low-level and deep-layer shear will be relatively
    strong, and the potential will exist for isolated severe weather, on
    the condition that sufficient instability develops to sustain
    surface-based thunderstorms.

    ..Mead/Weinman.. 05/09/2026

    $$

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  • From COD Weather Processor@1:2320/107 to wx-storm@lists.illinois.edu on Saturday, May 09, 2026 12:05:31
    ACUS01 KWNS 091205
    SWODY1
    SPC AC 091203

    Day 1 Convective Outlook
    NWS Storm Prediction Center Norman OK
    0703 AM CDT Sat May 09 2026

    Valid 091300Z - 101200Z

    ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS MUCH OF WESTERN/CENTRAL OKLAHOMA...

    ...SUMMARY...
    Widely scattered severe thunderstorms capable of large to very large
    hail, locally damaging wind gusts, and perhaps a few tornadoes are
    possible in parts of western into central Oklahoma Saturday
    afternoon and evening. Sparser large hail and damaging wind
    occurrences are possible across the Gulf Coast states, the northern
    and central High Plains, the Great Lakes, and possibly mid-Atlantic.

    ...Plains...
    A flat upper ridge will be present today over the southwest states
    and southern Rockies, while stronger flow aloft extends from the
    northern Rockies into the mid MS Valley and eastern states. The
    cold front that triggered convection over OK on Friday has stalled
    over north TX and will slowly return northward through the day
    today. Despite relatively weak low-level winds, dewpoints will
    climb through the 50s across western OK leading to an axis of
    moderate CAPE by late afternoon. Strong heating along/behind a
    diffuse dryline will likely lead to isolated thunderstorm
    development. Steep mid-level lapse rates and strong deep-layer
    shear will promote supercell storm structures capable of large hail.
    Given the weak forcing aloft, storm coverage is likely to be rather
    sparse through the evening. But those storms that can persist will
    be in a progressively more moist and sheared environment that could
    support the risk of a tornado or two.

    Elsewhere farther north, steep low and mid-level lapse rates will
    promote a risk of scattered high-based afternoon thunderstorms
    capable of gusty winds and hail from eastern WY/CO into western
    NE/KS.

    ...Gulf Coast...
    Clusters of thunderstorms are ongoing this morning over parts of
    LA/MS/AL. This activity will persist through the day and spread
    eastward. Limited heating and rather weak shear profiles will limit
    the overall severe threat. But nevertheless a few storms may
    occasionally become intense - capable of gusty/damaging winds and
    hail.

    ...Lower Great Lakes and Mid Atlantic...
    A large upper trough will track from Ontario into Quebec today,
    while the associated cold front sweeps southeastward across the
    lower Great Lakes region. Sufficient instability is forecast to
    support a line of thunderstorms forming over Lakes Erie/Ontario and
    spreading into parts of OH/PA/NY this evening. Gusty winds and
    small hail are expected, with a few reports of severe wind/hail
    possible.

    A corridor of moderate surface heating will extend from central VA
    into NJ today, helping to destabilize this region and lead to widely
    scattered afternoon thunderstorms. CAM solutions suggest the storms
    that form will struggle to organize/intensify, but there will be
    sufficient CAPE/shear to support some risk of a damaging wind gust
    or two through early evening.

    ..Hart/Wendt.. 05/09/2026

    $$

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  • From COD Weather Processor@1:2320/107 to wx-storm@lists.illinois.edu on Saturday, May 09, 2026 16:32:30
    ACUS01 KWNS 091632
    SWODY1
    SPC AC 091630

    Day 1 Convective Outlook
    NWS Storm Prediction Center Norman OK
    1130 AM CDT Sat May 09 2026

    Valid 091630Z - 101200Z

    ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF WESTERN/CENTRAL OKLAHOMA AND WESTERN NORTH TEXAS...

    ...SUMMARY...
    Widely scattered severe thunderstorms capable of producing mainly
    large to very large hail and locally damaging winds appear possible
    for parts of western/central Oklahoma this afternoon through
    tonight. Isolated hail and damaging winds may also occur across
    portions of the Gulf Coast states, central High Plains, Great Lakes,
    and Mid-Atlantic.

    ...Southern/Central Plains...
    High-based convection is forecast to develop this afternoon across
    southeast WY and vicinity as a mid-level shortwave trough progresses southeastward across the northern/central High Plains. While
    low-level moisture is expected to remain quite limited, cool
    temperatures aloft and a well-mixed boundary layer will support a
    risk for isolated severe wind gusts and perhaps some hail with the
    more robust convection. This activity should spread southeastward
    across parts of the central High Plains through the afternoon and
    evening, while continuing to pose an isolated severe threat.

    Low-level moisture is somewhat greater across the southern High
    Plains, but still quite shallow per 12Z observed soundings from
    OUN/FWD. While large-scale ascent will remain weaker with southward
    extent through the day across this region, a surface dryline will
    extend across the eastern TX Panhandle vicinity by peak afternoon
    heating. Most guidance continues to suggest an uncapped and
    moderately unstable airmass will exist along/east of this dryline
    across western OK. Isolated to widely scattered thunderstorms may
    initiate by late afternoon/early evening. If this occurs, then a few
    supercells capable of producing mainly large to very large hail
    appear possible. The well-mixed boundary layer and shallow low-level
    moisture suggest a low risk for a tornado or two through early
    evening, before low-level shear gradually increases through late
    evening. There is also a signal for convection to form/spread
    southeastward from KS/northern OK into central OK late tonight/early
    Sunday morning. If this scenario occurs, then a severe wind threat
    may exist with any sustained clusters given a favorable
    thermodynamic and kinematic environment.

    ...Coastal Texas into the Lower Mississippi Valley/Southeast...
    A weak mid-level trough over central/east TX late this morning will
    continue to move eastward into the western Gulf through this
    evening. Stronger convection across deep south TX has recently moved
    offshore, but additional thunderstorms may develop this afternoon
    across parts of coastal/southeast TX into LA in close proximity to
    the mid-level trough. Cool temperatures aloft atop a moist low-level
    airmass will support moderate to locally strong instability. This
    coupled with sufficient deep-layer shear may foster modest updraft
    organization and an isolated risk for large hail and damaging winds
    with the stronger cores that form. Across the central Gulf Coast
    states, widespread precipitation and ongoing convection has
    reinforced the surface front near the coast. Any appreciable risk
    for occasional damaging winds should remain along/south of this
    convectively reinforced boundary through the afternoon. Therefore,
    the Marginal Risk has been adjusted southward with this update.

    ...Great Lakes...
    Beneath upper troughing centered over Ontario, a surface cold front
    will advance east-southeastward across the Great Lakes through the
    period. Only modest low-level moisture (generally low to mid 50s
    surface dewpoints) will be in place ahead of this front from
    southeast Lower MI into the lower Great Lakes. Still, strong
    mid-level flow may be mixed towards the surface as low-level lapse
    rates continue to steepen this afternoon. Accordingly, thunderstorms
    that develop along/ahead of the cold front should pose a threat for
    at least isolated damaging winds, and perhaps some hail with any
    marginal supercell structures. The overall thermodynamic environment
    appears too limited to justify greater severe wind probabilities at
    this time.

    ...Mid-Atlantic...
    Given ongoing cloud cover and precipitation, confidence remains
    fairly low that sufficient instability to support sustained
    surface-based convection will exist this afternoon across the
    eastern Mid-Atlantic. Still, a low chance for a stronger
    thunderstorm or two may focus across parts of NJ and vicinity, where
    weak instability should overlap with modest deep-layer shear.

    ..Gleason/Chalmers.. 05/09/2026

    $$

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  • From COD Weather Processor@1:2320/107 to wx-storm@lists.illinois.edu on Saturday, May 09, 2026 20:00:32
    ACUS01 KWNS 092000
    SWODY1
    SPC AC 091958

    Day 1 Convective Outlook
    NWS Storm Prediction Center Norman OK
    0258 PM CDT Sat May 09 2026

    Valid 092000Z - 101200Z

    ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS NORTHWEST
    TEXAS AND CENTRAL TO WESTERN OKLAHOMA AS WELL AS PORTIONS OF THE
    LOWER GREAT LAKES...

    ...SUMMARY...
    Widely scattered severe thunderstorms capable of producing mainly
    large to very large hail and locally damaging winds appear possible
    for parts of western/central Oklahoma this afternoon through
    tonight. Isolated hail and damaging winds may also occur across
    portions of the Texas and Louisiana Gulf Coast, central High Plains,
    Great Lakes, and Mid-Atlantic.

    ...20z Update...
    15% wind risk probabilities were introduced to the eastern shore of
    Lake Erie downstream of a developing squall line. Although buoyancy
    across this region remains fairly weak (around 500 J/kg MLCAPE per
    recent mesoanalysis estimates), boundary-layer mixing is noted along
    the eastern shore that may facilitate downward momentum transfer as
    the squall line moves onshore. Additionally, latest time-lagged
    HRRR/RRFS ensembles have shown a consistent signal for 45-60 mph
    gusts associated with the line during the late afternoon/evening
    hours, hinting that a localized corridor of higher wind potential
    may materialize.

    ...Northern Gulf Coast/Northern Florida...
    Severe probabilities along the northern Gulf Coast and across
    northern Florida have been reduced based on recent convective
    trends. Latest radar/satellite imagery depicts a frontal boundary
    pushing south into the northern Gulf with limited MUCAPE noted in
    recent mesoanalyses north of the boundary. Across northern FL,
    convection developing along the frontal zone has struggled to
    maintain intensity - likely owing to marginal forcing for ascent and
    poor mid-level lapse rates sampled by a recent 18 UTC JAX sounding.
    Severe wind probabilities have largely been adjusted across
    northeastern FL to reflect where stronger heating/better buoyancy
    will likely support more robust updrafts through late afternoon.

    ...Eastern Texas Panhandle...
    Severe hail/wind probabilities have been adjusted west from western
    OK into the eastern TX Panhandle where dewpoints are climbing into
    the low/mid 50s and shallow cumulus is beginning to develop along
    the dryline. These trends hint that the severe risk may emerge
    slightly further west than depicted by previous forecasts and
    guidance.

    Elsewhere, the forecast remains on track. See the previous
    discussion below and MCDs 684, 685, and 686 for additional details.

    ..Moore.. 05/09/2026

    .PREV DISCUSSION... /ISSUED 1130 AM CDT Sat May 09 2026/

    ...Southern/Central Plains...
    High-based convection is forecast to develop this afternoon across
    southeast WY and vicinity as a mid-level shortwave trough progresses southeastward across the northern/central High Plains. While
    low-level moisture is expected to remain quite limited, cool
    temperatures aloft and a well-mixed boundary layer will support a
    risk for isolated severe wind gusts and perhaps some hail with the
    more robust convection. This activity should spread southeastward
    across parts of the central High Plains through the afternoon and
    evening, while continuing to pose an isolated severe threat.

    Low-level moisture is somewhat greater across the southern High
    Plains, but still quite shallow per 12Z observed soundings from
    OUN/FWD. While large-scale ascent will remain weaker with southward
    extent through the day across this region, a surface dryline will
    extend across the eastern TX Panhandle vicinity by peak afternoon
    heating. Most guidance continues to suggest an uncapped and
    moderately unstable airmass will exist along/east of this dryline
    across western OK. Isolated to widely scattered thunderstorms may
    initiate by late afternoon/early evening. If this occurs, then a few
    supercells capable of producing mainly large to very large hail
    appear possible. The well-mixed boundary layer and shallow low-level
    moisture suggest a low risk for a tornado or two through early
    evening, before low-level shear gradually increases through late
    evening. There is also a signal for convection to form/spread
    southeastward from KS/northern OK into central OK late tonight/early
    Sunday morning. If this scenario occurs, then a severe wind threat
    may exist with any sustained clusters given a favorable
    thermodynamic and kinematic environment.

    ...Coastal Texas into the Lower Mississippi Valley/Southeast...
    A weak mid-level trough over central/east TX late this morning will
    continue to move eastward into the western Gulf through this
    evening. Stronger convection across deep south TX has recently moved
    offshore, but additional thunderstorms may develop this afternoon
    across parts of coastal/southeast TX into LA in close proximity to
    the mid-level trough. Cool temperatures aloft atop a moist low-level
    airmass will support moderate to locally strong instability. This
    coupled with sufficient deep-layer shear may foster modest updraft
    organization and an isolated risk for large hail and damaging winds
    with the stronger cores that form. Across the central Gulf Coast
    states, widespread precipitation and ongoing convection has
    reinforced the surface front near the coast. Any appreciable risk
    for occasional damaging winds should remain along/south of this
    convectively reinforced boundary through the afternoon. Therefore,
    the Marginal Risk has been adjusted southward with this update.

    ...Great Lakes...
    Beneath upper troughing centered over Ontario, a surface cold front
    will advance east-southeastward across the Great Lakes through the
    period. Only modest low-level moisture (generally low to mid 50s
    surface dewpoints) will be in place ahead of this front from
    southeast Lower MI into the lower Great Lakes. Still, strong
    mid-level flow may be mixed towards the surface as low-level lapse
    rates continue to steepen this afternoon. Accordingly, thunderstorms
    that develop along/ahead of the cold front should pose a threat for
    at least isolated damaging winds, and perhaps some hail with any
    marginal supercell structures. The overall thermodynamic environment
    appears too limited to justify greater severe wind probabilities at
    this time.

    ...Mid-Atlantic...
    Given ongoing cloud cover and precipitation, confidence remains
    fairly low that sufficient instability to support sustained
    surface-based convection will exist this afternoon across the
    eastern Mid-Atlantic. Still, a low chance for a stronger
    thunderstorm or two may focus across parts of NJ and vicinity, where
    weak instability should overlap with modest deep-layer shear.

    $$

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  • From COD Weather Processor@1:2320/107 to wx-storm@lists.illinois.edu on Sunday, May 10, 2026 00:57:33
    ACUS01 KWNS 100057
    SWODY1
    SPC AC 100055

    Day 1 Convective Outlook
    NWS Storm Prediction Center Norman OK
    0755 PM CDT Sat May 09 2026

    Valid 100100Z - 101200Z

    ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS WESTERN...CENTRAL...AND SOUTHERN OKLAHOMA INTO NORTH TEXAS...

    ...SUMMARY...
    Scattered severe storms capable of large hail and damaging winds are
    expected to continue tonight across western, central, and southern
    Oklahoma and north Texas. Isolated occurrences of wind and/or hail
    are possible through the remainder of the evening over the central
    High Plains, Texas Coast, and lower Great Lakes.

    ...Oklahoma and North Texas...

    As of 00:30z, a cluster of supercells with a history of large hail
    production is present along and just to the south of I-40 in western
    OK with additional storms intensifying ahead of a cold front
    northwest of Woodward. The storms are occurring within a narrow axis
    of modest instability with MLCAPE of 500-1000 J/kg, which coincides
    with effective bulk shear magnitudes of 45-50 kt.
    A comparably more moist boundary layer resides to the south of the
    current convection across southern OK into north TX with dewpoints
    in the upper 50s to around 60, supporting MLCAPE up to 1500 J/kg.

    Recent, convection-allowing model guidance is suggestive that a
    consolidation of the separate convective regimes will occur later
    this evening with an increasing damaging wind threat spreading
    southeast through central and southern OK and north TX. Another
    possible scenario is for the I-40 supercell complex to gradually
    evolve into a forward-propagating system with an attendant damaging
    wind and hail threat confined to southern OK and potentially north
    TX. Either of these scenarios appear plausible as a nocturnally
    strengthening low-level jet enhances inflow of the more
    moist/unstable air mass into the growing convective system. In
    either scenario, it appears the damaging wind threat will develop to
    the east of the current 15% unconditional probability. As such, that
    line (delineating the level 2/Slight Risk) has been extended into
    portions of southeast OK, and farther east in north TX.


    ...Western New York into Northeast Ohio...

    As of 00z, a band of thunderstorms is ongoing from portions of
    western NY through northwest PA into eastern OH, ahead of a vigorous
    short-wave trough moving through the Great Lakes region. Steep
    low/mid-level lapse rates have contributed to sufficient instability
    to sustain the ongoing storms with a number of 40-50+ mph wind gusts
    reported earlier in the Cleveland area. Locally strong to marginally
    severe wind gusts will remain possible for the next hour or two
    before low-level lapse rates weaken with the cooling of the boundary
    layer.


    ...Central High Plains...

    A small cluster of thunderstorms is ongoing this evening in
    northeast CO with a more isolated storm in northwest KS, near
    Goodland. Forcing for ascent associated with a vigorous short-wave
    trough moving through WY coupled with a steep, low/mid-level lapse
    rate environment are supporting that convective development amidst a
    kinematic environment featuring 40-50 kt of effective bulk shear.
    The potential for isolated occurrences of large hail and/or locally
    damaging wind gusts are expected to continue through the remainder
    of the evening before boundary-layer cooling and resultant
    convective inhibition accrual result in a decreasing severe-weather
    threat.


    ...Texas Coast to Lower Sabine River Valley...

    Isolated strong to severe storms this evening within a moist and
    moderately unstable air mass with estimated MLCAPE up to 2000-2500
    J/kg. Vertical shear isn't particularly strong, nor is large-scale
    forcing for ascent. As such, isolated large hail and/or strong wind
    gusts will remain possible for the next couple of hours before
    storms weaken with the loss of daytime heating.

    ..Mead.. 05/10/2026

    $$

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  • From COD Weather Processor@1:2320/107 to wx-storm@lists.illinois.edu on Sunday, May 10, 2026 05:34:36
    ACUS01 KWNS 100534
    SWODY1
    SPC AC 100533

    Day 1 Convective Outlook
    NWS Storm Prediction Center Norman OK
    1233 AM CDT Sun May 10 2026

    Valid 101200Z - 111200Z

    ...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS SUNDAY
    AFTERNOON THROUGH LATE EVENING ACROSS PARTS OF CENTRAL AND NORTH
    TEXAS...

    ...SUMMARY...
    Large hail (some in excess of 2 inches in diameter) and severe wind
    gusts (potentially in excess of 75 mph) will be possible Sunday afternoon/evening across parts of central and north Texas. More
    sporadic occurrences of damaging wind and large hail are possible
    farther east into the lower Mississippi Valley, portions of the
    Florida Peninsula, and central New Mexico into far West Texas.

    ...Synopsis...

    A mid/upper-level low initially over James Bay will progress
    northeast through the forecast period, with a belt of strong,
    cyclonic flow persisting across the Great Lakes and New England. On
    the periphery of the broader-scale troughing, late evening water
    vapor imagery shows a short-wave trough over WY with a more subtle
    disturbance noted near the Four Corners region. Those two features
    are expected to progress into the southern Plains by Sunday
    afternoon, contributing to modest, mid-level height falls across the
    region.

    At the surface, a cold front initially from the lower Great Lakes
    southwest through the OH Valley and Ozark Plateau into the southern
    High Plains at 12z Sunday will advance east/southeast during the
    day. A few strong storms capable of small hail and gusty winds may
    occur along and ahead of that boundary Sunday afternoon over
    northern New England and the central Appalachians into mid-Atlantic.
    Greater severe-storm potential is expected along the cold front and
    any preceding convective outflow boundaries from the southern Plains
    into lower MS Valley Sunday afternoon and evening.


    ...Southern Plains into Lower MS Valley...

    Clusters of thunderstorms (some of which could be strong to severe)
    are likely to be ongoing Sunday morning from the ArkLaTex into OK,
    with outflow associated with that activity preceding the cold front
    across north Texas. By early to mid afternoon, the composite
    boundary is expected to extend from the TX South Plains across north
    Texas through the ArkLaTex into central or eastern AR. A dryline is
    expected to stretch south from the front through the eastern Permian
    Basin into the Edwards Plateau region.

    A steep, mid-level lapse rate plume will overlie the warm sector
    characterized by increasing boundary-layer moisture content with
    eastward extent across TX, with afternoon MLCAPE of 2500-3500 J/kg.
    Slightly less instability (MLCAPE of 1000-2000 J/kg) is forecast
    from AR and LA into MS as that region will reside east of the EML
    plume.

    The combination of daytime heating and increasing forcing for ascent
    (see synopsis) are expected to support thunderstorm development by
    mid afternoon from the vicinity of the surface triple point over
    west-central TX, east along the composite boundary. Vertical shear
    will be maximized along the west-to-east-oriented front with
    decreasing bulk shear magnitudes with southward extent across the
    warm sector. As such, supercell storm modes and an associated large
    to very large hail (2+" in diameter) threat are most probable in the
    vicinity of the front within the first couple of hours after storm
    initiation.

    By late afternoon into Sunday evening, there is a consistent signal
    across convection-allowing model guidance for upscale growth into a forward-propagating QLCS that accelerates southeast through central
    TX before reaching the TX Coast and deep South TX early Monday
    morning. The degree of parcel buoyancy and presence of a dry,
    mid-level air mass will support the potential for organized cold
    pool development with corridors of damaging winds in excess of 75
    mph appearing possible from late afternoon through evening. The
    damaging wind threat is expected to become more isolated with time
    Sunday night into early Monday as the boundary layer gradually
    stabilizes. Generally weak low-level shear (effective SRH < 150
    m2/s2) and 0-3-km bulk-shear magnitudes <25-30 kt are expected to
    limit tornado/meso-vortex potential with the QLCS.

    Farther to the east across AR and LA into MS, convective evolution
    and associated severe-weather potential are a bit more uncertain.
    Some model guidance suggests that morning storms across portions of
    AR could intensify by afternoon while spreading east/southeast into
    parts of northwest MS and northern LA. Additional strong to severe
    storms will also be possible Sunday afternoon and evening along the
    front moving through the area. Damaging wind gusts appear to be the
    primary severe hazard, though isolated occurrences of severe hail
    will also be possible.


    ...Central NM into far West Texas...

    Height falls aloft coupled with enhanced orographic ascent with the cold-frontal surge are expected to contribute to isolated to widely
    scattered storm development Sunday afternoon and evening. Steep,
    low/mid-level lapse rates will contribute to MLCAPE of around 500
    J/kg amidst 30-35 kt of effective bulk shear may favor a few strong
    to severe storms capable of hail and/or locally damaging wind gusts.


    ...FL Peninsula...

    Isolated to widely scattered, diurnally enhanced thunderstorms
    appear possible along the front stalled across the northern
    Peninsula, and south along the Atlantic Coast sea breeze. The
    presence of a moist environment with MLCAPE up to 1500-2500 J/kg
    will support water-loaded downdrafts capable of locally damaging
    wind gusts during the afternoon and early evening hours.

    ..Mead/Weinman.. 05/10/2026

    $$

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  • From COD Weather Processor@1:2320/107 to wx-storm@lists.illinois.edu on Sunday, May 10, 2026 11:57:42
    ACUS01 KWNS 101157
    SWODY1
    SPC AC 101156

    Day 1 Convective Outlook
    NWS Storm Prediction Center Norman OK
    0656 AM CDT Sun May 10 2026

    Valid 101300Z - 111200Z

    ...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF
    NORTHERN AND CENTRAL TEXAS...

    ...SUMMARY...
    Large hail (some in excess of 2 inches in diameter) and severe wind
    gusts (potentially in excess of 75 mph) will be possible this
    afternoon/evening across parts of central and north Texas. More
    sporadic occurrences of damaging wind and large hail are possible
    farther east into the lower Mississippi Valley, portions of the
    Florida Peninsula, and central New Mexico into far West Texas.

    ...TX...
    Morning water vapor imagery shows a mid-level shortwave trough
    digging southeastward across CO. This feature will emerge into the
    Plains this morning and track into OK/TX by this afternoon. Large
    scale ascent ahead of this trough has led to multiple clusters of
    thunderstorms overnight across OK and north TX, reinforcing
    cooler/stable air down into north-central TX. While some recovery
    of the air mass is expected, the primary surface boundary will
    likely extend across north TX by early afternoon. Strong heating to
    its south, coupled with dewpoints in the upper 60s and steep mid
    level lapse rates will yield strongly unstable CAPE (MLCAPE ~2500
    J/kg) from the Abilene area south/eastward.

    Thunderstorm development will occur first along/north of the primary
    boundary and the organizing surface low over west TX. Initial
    storms will likely be supercells capable of very large hail and a
    few damaging wind gusts. Model solutions are consistent in
    developing a large bowing cluster of storms that tracks across
    north-central TX through the evening. These storms will pose a risk
    of more widespread damaging wind and hail potential across the ENH
    risk area. Activity is expected to weaken overnight as it
    approaches the TX middle Gulf Coast.

    ..Hart/Wendt.. 05/10/2026

    $$

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  • From COD Weather Processor@1:2320/107 to wx-storm@lists.illinois.edu on Sunday, May 10, 2026 16:32:09
    ACUS01 KWNS 101632
    SWODY1
    SPC AC 101630

    Day 1 Convective Outlook
    NWS Storm Prediction Center Norman OK
    1130 AM CDT Sun May 10 2026

    Valid 101300Z - 111200Z

    ...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF
    TEXAS...

    ...SUMMARY...
    Scattered large hail (some 2+ inches) and numerous severe/damaging
    wind gusts (isolated 75+ mph) are expected this afternoon/evening
    across parts of west-central to central Texas. A couple of tornadoes
    also appear possible across parts of west-central Texas along/near a
    front.

    ...Texas into the ArkLaTex/Lower Mississippi Valley...
    Severe potential today will be complicated by ongoing thunderstorms
    along/near the Red River and a convectively reinforced outflow
    boundary across the ArkLaTex/lower MS Valley. In general, a
    favorable setup for scattered to numerous severe/damaging winds
    remains apparent this afternoon/evening across parts of west-central
    into north TX to the south of current convective activity, along
    with the potential for large to very large hail and perhaps a couple
    of tornadoes with initial supercells that may develop.

    Recent surface analysis shows a low over northwest TX, with a
    dryline extending southward to the Big Bend region. A cold front
    arcing northeastward from the low across western north TX into
    southern OK and western/northern AR will likely serve as a focus for
    additional robust thunderstorm development this afternoon. The
    observed 12Z FWD sounding sampled the pre-convective airmass well,
    with steep mid-level lapse rates atop a rather moist low-level
    airmass aiding MUCAPE around 2500 J/kg.

    There is some uncertainty regarding airmass recovery with eastward
    extent towards the ArkLaTex given a notable outflow boundary from
    earlier convection noted on latest visible satellite imagery
    extending from north-central to east-central TX. Still, this
    boundary seems to have stalled recently, with mostly clear skies to
    its north across northeast TX ahead of ongoing thunderstorms in
    north-central TX. Current expectations are for moderate to strong
    instability to develop this afternoon as diurnal heating occurs
    across west-central to north TX, with the greatest instability
    focused south of the cold front/outflow and east of the dryline.

    Stronger west-northwesterly mid-level flow associated with a southeastward-moving shortwave trough may tend to remain displaced
    along and slightly to the north of the cold front through the day.
    Still, sufficient overlap of modestly enhanced mid-level winds and
    related deep-layer shear is forecast across the northern portions of
    the warm sector in TX. This shear should support some supercells
    with initial development, particularly across parts of west-central
    into north-central TX. Large to isolated very large hail (2+ inches)
    may occur with these supercells, before convection quickly grows
    upscale into an intense bowing cluster. A narrow zone of tornado
    potential is also apparent with the supercells across parts of
    west-central TX near the sagging front, where low-level shear will
    be locally enhanced by east-northeasterly near-surface winds.

    Scattered to numerous severe/damaging winds are expected across much
    of central TX after this mode transition occurs. With ample
    instability and a highly organized cold pool expected, some of these
    gusts could exceed 75 mph on a localized basis. The severe/damaging
    wind threat should continue through the evening as the bowing
    cluster spreads south-southeastward across much of TX. Eventual
    weakening is forecast late tonight into early Monday morning,
    although at least an isolated damaging wind threat may persist into south/coastal TX through the end of the period.

    Lower confidence in organized severe potential exists with eastward
    extent into the ArkLaTex and lower MS Valley, as ongoing cloud cover
    and outflow from earlier convection may inhibit diurnal heating and
    the development of any more than weak instability this afternoon.
    Still, some chance for redevelopment remains apparent along/east of
    the cold front, so severe hail/wind probabilities have been
    maintained with adjustments based on current observations and latest
    short-term guidance.

    ...Central New Mexico into Far West Texas...
    Low-level orographic ascent with the surging cold front should
    support isolated to widely scattered thunderstorms developing across
    central NM into parts of far west TX this afternoon and evening.
    Cool temperatures aloft will aid in the development of weak
    instability, even with limited low-level moisture. Around 30-35 kt
    of effective bulk shear should foster organized updrafts, with the
    strongest cores capable of producing isolated hail and occasional severe/damaging winds.

    ...Florida...
    Isolated to widely scattered thunderstorms should develop along the
    stalled front this afternoon across the northern FL Peninsula, and
    southward along the Atlantic Coast sea breeze. Diurnal heating of a
    moist low-level airmass, with MLCAPE up to 1500-2000 J/kg, should
    support water-loaded downdrafts capable of producing locally
    damaging winds. Sufficient deep-layer shear may also foster
    sufficient updraft organization for isolated hail with the more
    robust cores.

    ...Mid-Atlantic...
    Strong to locally damaging winds may occur with high-based
    convection that forms on the Appalachians/Blue Ridge this afternoon
    and subsequently spreads east-northeastward along/ahead of a cold
    front. While instability will remain weak, a deeply mixed boundary
    layer should encourage gusty downdraft winds to reach the surface in
    a narrow corridor where a Marginal Risk has been introduced.

    ..Gleason/Chalmers.. 05/10/2026

    $$

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  • From COD Weather Processor@1:2320/107 to wx-storm@lists.illinois.edu on Sunday, May 10, 2026 16:40:10
    ACUS01 KWNS 101640
    SWODY1
    SPC AC 101638

    Day 1 Convective Outlook
    NWS Storm Prediction Center Norman OK
    1138 AM CDT Sun May 10 2026

    Valid 101630Z - 111200Z

    ...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF
    TEXAS...

    ...SUMMARY...
    Scattered large hail (some 2+ inches) and numerous severe/damaging
    wind gusts (isolated 75+ mph) are expected this afternoon/evening
    across parts of west-central to central Texas. A couple of tornadoes
    also appear possible across parts of west-central Texas along/near a
    front.

    ...Texas into the ArkLaTex/Lower Mississippi Valley...
    Severe potential today will be complicated by ongoing thunderstorms
    along/near the Red River and a convectively reinforced outflow
    boundary across the ArkLaTex/lower MS Valley. In general, a
    favorable setup for scattered to numerous severe/damaging winds
    remains apparent this afternoon/evening across parts of west-central
    into north TX to the south of current convective activity, along
    with the potential for large to very large hail and perhaps a couple
    of tornadoes with initial supercells that may develop.

    Recent surface analysis shows a low over northwest TX, with a
    dryline extending southward to the Big Bend region. A cold front
    arcing northeastward from the low across western north TX into
    southern OK and western/northern AR will likely serve as a focus for
    additional robust thunderstorm development this afternoon. The
    observed 12Z FWD sounding sampled the pre-convective airmass well,
    with steep mid-level lapse rates atop a rather moist low-level
    airmass aiding MUCAPE around 2500 J/kg.

    There is some uncertainty regarding airmass recovery with eastward
    extent towards the ArkLaTex given a notable outflow boundary from
    earlier convection noted on latest visible satellite imagery
    extending from north-central to east-central TX. Still, this
    boundary seems to have stalled recently, with mostly clear skies to
    its north across northeast TX ahead of ongoing thunderstorms in
    north-central TX. Current expectations are for moderate to strong
    instability to develop this afternoon as diurnal heating occurs
    across west-central to north TX, with the greatest instability
    focused south of the cold front/outflow and east of the dryline.

    Stronger west-northwesterly mid-level flow associated with a southeastward-moving shortwave trough may tend to remain displaced
    along and slightly to the north of the cold front through the day.
    Still, sufficient overlap of modestly enhanced mid-level winds and
    related deep-layer shear is forecast across the northern portions of
    the warm sector in TX. This shear should support some supercells
    with initial development, particularly across parts of west-central
    into north-central TX. Large to isolated very large hail (2+ inches)
    may occur with these supercells, before convection quickly grows
    upscale into an intense bowing cluster. A narrow zone of tornado
    potential is also apparent with the supercells across parts of
    west-central TX near the sagging front, where low-level shear will
    be locally enhanced by east-northeasterly near-surface winds.

    Scattered to numerous severe/damaging winds are expected across much
    of central TX after this mode transition occurs. With ample
    instability and a highly organized cold pool expected, some of these
    gusts could exceed 75 mph on a localized basis. The severe/damaging
    wind threat should continue through the evening as the bowing
    cluster spreads south-southeastward across much of TX. Eventual
    weakening is forecast late tonight into early Monday morning,
    although at least an isolated damaging wind threat may persist into south/coastal TX through the end of the period.

    Lower confidence in organized severe potential exists with eastward
    extent into the ArkLaTex and lower MS Valley, as ongoing cloud cover
    and outflow from earlier convection may inhibit diurnal heating and
    the development of any more than weak instability this afternoon.
    Still, some chance for redevelopment remains apparent along/east of
    the cold front, so severe hail/wind probabilities have been
    maintained with adjustments based on current observations and latest
    short-term guidance.

    ...Central New Mexico into Far West Texas...
    Low-level orographic ascent with the surging cold front should
    support isolated to widely scattered thunderstorms developing across
    central NM into parts of far west TX this afternoon and evening.
    Cool temperatures aloft will aid in the development of weak
    instability, even with limited low-level moisture. Around 30-35 kt
    of effective bulk shear should foster organized updrafts, with the
    strongest cores capable of producing isolated hail and occasional severe/damaging winds.

    ...Florida...
    Isolated to widely scattered thunderstorms should develop along the
    stalled front this afternoon across the northern FL Peninsula, and
    southward along the Atlantic Coast sea breeze. Diurnal heating of a
    moist low-level airmass, with MLCAPE up to 1500-2000 J/kg, should
    support water-loaded downdrafts capable of producing locally
    damaging winds. Sufficient deep-layer shear may also foster
    sufficient updraft organization for isolated hail with the more
    robust cores.

    ...Mid-Atlantic...
    Strong to locally damaging winds may occur with high-based
    convection that forms on the Appalachians/Blue Ridge this afternoon
    and subsequently spreads east-northeastward along/ahead of a cold
    front. While instability will remain weak, a deeply mixed boundary
    layer should encourage gusty downdraft winds to reach the surface in
    a narrow corridor where a Marginal Risk has been introduced.

    ..Gleason/Chalmers.. 05/10/2026

    $$

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  • From COD Weather Processor@1:2320/107 to wx-storm@lists.illinois.edu on Sunday, May 10, 2026 20:00:38
    ACUS01 KWNS 102000
    SWODY1
    SPC AC 101958

    Day 1 Convective Outlook
    NWS Storm Prediction Center Norman OK
    0258 PM CDT Sun May 10 2026

    Valid 102000Z - 111200Z

    ...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF WESTERN/CENTRAL TEXAS...

    ...SUMMARY...
    Scattered large hail (some 2+ inches) and numerous severe/damaging
    wind gusts (isolated 75+ mph) are expected this afternoon/evening
    across parts of west-central to central Texas. A couple of tornadoes
    also appear possible across parts of west-central Texas along/near a
    front.

    ...20z Update...
    The previous forecast remains largely on track with only minor
    adjustments required based on recent observed trends. The
    convectively reinforced cold front across northwest TX continues to
    surge south faster than anticipated by morning guidance.
    Nonetheless, elevated supercell development is ongoing immediately
    north of the boundary where MUCAPE was recently analyzed near 2000
    J/kg. Consequently, severe hail probabilities (and the ENH
    categorical bounds) have largely been left in place with only a
    southward reduction in the wind and tornado probabilities based on
    the expected 20 UTC frontal position.

    Across central to southern TX, recent HRRR/RRFS time-lagged
    ensembles depict the potential for 75+ mph winds across the
    Austin/San Antonio region and southward into south TX late tonight.
    This signal appears reasonable given the expected evolution of the
    eventual MCS and downstream environment (both sampled by recent
    ACARS soundings and forecast by short-range guidance). The 15% wind
    and Intensity Level 1 contours have been expanded south to address
    this potential.

    Across northeast TX, the remnants of an early-morning MCS have
    transitioned into a single organized supercell that has begun
    weakening over the past 20-30 minutes. However, attempts at new
    convective development are noted along the outflow boundary to the
    south of the decaying supercell. With temperatures in the mid 80s
    along/south of the boundary, lingering inhibition should be
    minimized and may allow for additional strong/severe thunderstorms
    through early evening with an attendant threat for severe hail/wind.

    Elsewhere, the forecast remains on track. See the previous
    discussion below and MCDs 693, 694, and 695 for additional
    short-term details.

    ..Moore.. 05/10/2026

    .PREV DISCUSSION... /ISSUED 1138 AM CDT Sun May 10 2026/

    ...Texas into the ArkLaTex/Lower Mississippi Valley...
    Severe potential today will be complicated by ongoing thunderstorms
    along/near the Red River and a convectively reinforced outflow
    boundary across the ArkLaTex/lower MS Valley. In general, a
    favorable setup for scattered to numerous severe/damaging winds
    remains apparent this afternoon/evening across parts of west-central
    into north TX to the south of current convective activity, along
    with the potential for large to very large hail and perhaps a couple
    of tornadoes with initial supercells that may develop.

    Recent surface analysis shows a low over northwest TX, with a
    dryline extending southward to the Big Bend region. A cold front
    arcing northeastward from the low across western north TX into
    southern OK and western/northern AR will likely serve as a focus for
    additional robust thunderstorm development this afternoon. The
    observed 12Z FWD sounding sampled the pre-convective airmass well,
    with steep mid-level lapse rates atop a rather moist low-level
    airmass aiding MUCAPE around 2500 J/kg.

    There is some uncertainty regarding airmass recovery with eastward
    extent towards the ArkLaTex given a notable outflow boundary from
    earlier convection noted on latest visible satellite imagery
    extending from north-central to east-central TX. Still, this
    boundary seems to have stalled recently, with mostly clear skies to
    its north across northeast TX ahead of ongoing thunderstorms in
    north-central TX. Current expectations are for moderate to strong
    instability to develop this afternoon as diurnal heating occurs
    across west-central to north TX, with the greatest instability
    focused south of the cold front/outflow and east of the dryline.

    Stronger west-northwesterly mid-level flow associated with a southeastward-moving shortwave trough may tend to remain displaced
    along and slightly to the north of the cold front through the day.
    Still, sufficient overlap of modestly enhanced mid-level winds and
    related deep-layer shear is forecast across the northern portions of
    the warm sector in TX. This shear should support some supercells
    with initial development, particularly across parts of west-central
    into north-central TX. Large to isolated very large hail (2+ inches)
    may occur with these supercells, before convection quickly grows
    upscale into an intense bowing cluster. A narrow zone of tornado
    potential is also apparent with the supercells across parts of
    west-central TX near the sagging front, where low-level shear will
    be locally enhanced by east-northeasterly near-surface winds.

    Scattered to numerous severe/damaging winds are expected across much
    of central TX after this mode transition occurs. With ample
    instability and a highly organized cold pool expected, some of these
    gusts could exceed 75 mph on a localized basis. The severe/damaging
    wind threat should continue through the evening as the bowing
    cluster spreads south-southeastward across much of TX. Eventual
    weakening is forecast late tonight into early Monday morning,
    although at least an isolated damaging wind threat may persist into south/coastal TX through the end of the period.

    Lower confidence in organized severe potential exists with eastward
    extent into the ArkLaTex and lower MS Valley, as ongoing cloud cover
    and outflow from earlier convection may inhibit diurnal heating and
    the development of any more than weak instability this afternoon.
    Still, some chance for redevelopment remains apparent along/east of
    the cold front, so severe hail/wind probabilities have been
    maintained with adjustments based on current observations and latest
    short-term guidance.

    ...Central New Mexico into Far West Texas...
    Low-level orographic ascent with the surging cold front should
    support isolated to widely scattered thunderstorms developing across
    central NM into parts of far west TX this afternoon and evening.
    Cool temperatures aloft will aid in the development of weak
    instability, even with limited low-level moisture. Around 30-35 kt
    of effective bulk shear should foster organized updrafts, with the
    strongest cores capable of producing isolated hail and occasional severe/damaging winds.

    ...Florida...
    Isolated to widely scattered thunderstorms should develop along the
    stalled front this afternoon across the northern FL Peninsula, and
    southward along the Atlantic Coast sea breeze. Diurnal heating of a
    moist low-level airmass, with MLCAPE up to 1500-2000 J/kg, should
    support water-loaded downdrafts capable of producing locally
    damaging winds. Sufficient deep-layer shear may also foster
    sufficient updraft organization for isolated hail with the more
    robust cores.

    ...Mid-Atlantic...
    Strong to locally damaging winds may occur with high-based
    convection that forms on the Appalachians/Blue Ridge this afternoon
    and subsequently spreads east-northeastward along/ahead of a cold
    front. While instability will remain weak, a deeply mixed boundary
    layer should encourage gusty downdraft winds to reach the surface in
    a narrow corridor where a Marginal Risk has been introduced.

    $$

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  • From COD Weather Processor@1:2320/107 to wx-storm@lists.illinois.edu on Monday, May 11, 2026 00:31:40
    ACUS01 KWNS 110031
    SWODY1
    SPC AC 110030

    Day 1 Convective Outlook
    NWS Storm Prediction Center Norman OK
    0730 PM CDT Sun May 10 2026

    Valid 110100Z - 111200Z

    ...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS THIS EVENING
    INTO TONIGHT IN CENTRAL TEXAS...

    ...SUMMARY...
    Scattered large hail (some 2+ inches) and numerous severe/damaging
    wind gusts (isolated 75+ mph) are expected this evening across parts
    of central Texas.

    ...Central Texas to the Texas Coast and deep South Texas...

    As of 00:15z, volumetric radar data indicated an HP supercell
    gradually evolving into a larger-scale bowing complex over
    McCulloch, San Saba, and Mason counties with a separate supercell
    complex over Coryell county, which recently produced hail up to four
    inches in diameter. Surface observations and objective analysis
    indicate the presence of a warm and moist inflow air mass with
    estimated MLCAPE of 2000-3000 J/kg. While deep-layer shear isn't
    particularly strong, the observed supercell structures indicate
    sufficient shear exists to support organized storm modes given the
    degree of instability.

    Current thinking is that the separate thunderstorm regimes mentioned
    above will eventually merge along a common cold pool, with a
    broader-scale MCS accelerating south-southeast through the remainder
    of central TX this evening. Corridors of damaging winds in excess of
    75 mph appear likely within the core of the bowing complex. The very
    large hail (> 2") threat is expected to persist for the next hour or
    two with the dominant supercell structures. Hail sizes should
    diminish with time as convection transitions to more of an outflow
    dominant system.

    The wind damage threat is expected to become more isolated late
    tonight as the convective system approaches the TX Coast and deep
    South Texas owing to gradual cooling and stabilization of the
    boundary layer.

    ..Mead.. 05/11/2026

    $$

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  • From COD Weather Processor@1:2320/107 to wx-storm@lists.illinois.edu on Monday, May 11, 2026 05:43:42
    ACUS01 KWNS 110543
    SWODY1
    SPC AC 110542

    Day 1 Convective Outlook
    NWS Storm Prediction Center Norman OK
    1242 AM CDT Mon May 11 2026

    Valid 111200Z - 121200Z

    ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS FROM THE COASTAL
    CAROLINAS INTO THE FLORIDA PENINSULA...AND ALONG THE CENTRAL GULF
    COAST...

    ...SUMMARY...
    Isolated severe storms with locally damaging wind gusts and hail are
    possible Monday afternoon from the coastal Carolinas into the
    Florida Peninsula, and along the central Gulf Coast.

    ...Synopsis...

    Within the base of broader-scale troughing over eastern North
    America, a lead short-wave trough will progress from the TN Valley
    through the Carolinas on Monday, in tandem with a mid-level jet
    streak. Farther to the southwest, a vorticity maximum over western
    TX as of late evening is expected to progress east through the
    Sabine River Valley to along the central Gulf Coast Monday afternoon
    into Monday night. Elsewhere, a strong short-wave trough and
    attending mid/upper-level wind maxima will crest the western U.S.
    ridge axis along the International Border before turning more
    southeast into the northern Plains and upper MS Valley Monday night
    into Tuesday morning.

    At the surface, a cold front will settle south through the lower MS
    Valley and Southeast with low pressure developing along the boundary
    over coastal SC or far southeast NC by early afternoon. Elsewhere,
    an area of low pressure will track east-southeast through southern
    parts of Saskatchewan and Manitoba with an associated cold front
    sweeping southeast through the northern High Plains. A trough will
    precede the cold front with that feature shifting east into the
    central Dakotas by early evening.


    ...Coastal Carolinas into the eastern Florida Peninsula...

    Latest model guidance is suggestive that surface-based thunderstorm
    development may occur as early a mid to late morning along or ahead
    of the cold front from the SC piedmont into the coastal plain as
    forcing for ascent increases downstream from the approaching
    short-wave trough. Subsequent storm development is also expected
    farther northeast along the front into southeast NC by late morning
    into early afternoon.

    Even with the relatively early storm development, forecast soundings
    indicate the presence of a moderately unstable warm sector with
    MLCAPE approaching 1500 J/kg. Vertical shear will steadily increase
    with the arrival mid-level jet streak, such that some transient
    supercell structures may evolve, especially in the vicinity of the
    weak surface low. The strongest storms will be capable of isolated
    occurrences of damaging winds and marginally severe hail into mid
    afternoon before moving offshore. Generally weak low-level shear
    should limit tornado potential.

    Additional strong to marginally severe storms appear possible along
    the cold front, as well as the Atlantic Coast sea breeze from
    southeast GA southward into the Fl Peninsula. The combination of a
    moist and moderately unstable air mass (MLCAPE of 1500-2500 J/kg)
    with 30-40 kt of effective bulk shear will be supportive of some
    storm organization with an attendant risk for damaging, wet
    microbursts and perhaps some marginally severe hail.


    ...Central Gulf Coast...

    Increased forcing for ascent associated with the short-wave trough
    moving into the Sabine River Valley is expected to contribute to an
    increase thunderstorm development Monday afternoon across southern
    parts of LA and MS, potentially into southwest AL. A moist and
    moderately unstable air mass will coincide with 30-35 kt of
    effective bulk shear, with the 00z convection-allowing models
    suggesting some potential for cold pool organization along the
    coast. The primary hazard is expected to be locally damaging outflow
    winds.


    ...Northern Plains into Upper Mississippi Valley...

    A plume of steep, mid-level lapse rates (7.5-8.5 C/km) will
    overspread the northern Plains Monday, downstream from the
    approaching short-wave trough. The boundary-layer ahead of the
    pre-frontal trough will remain rather dry with dewpoints in the 30s
    to perhaps low/mid 40s, which in turn will limit MLCAPE to 200-300
    J/kg. Strong, diurnal heating in the vicinity of the surface trough
    coupled with increasing height falls aloft may be sufficient to
    support isolated, high-based thunderstorms by late afternoon into
    early evening with the potential for locally strong wind gusts.
    Thunderstorms may tend to increase in areal coverage later Monday
    evening into Monday night across the upper MS Valley, aided by a
    nocturnally strengthening low-level jet. By that time, the
    convection is likely to be elevated and capable of small hail.

    No wind/hail probabilities will be assigned to the area at this
    time. However, model trends will be monitored for greater air mass destabilization, which could warrant 5% probabilities and a level
    1/Marginal Risk.

    ..Mead/Weinman.. 05/11/2026

    $$

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  • From COD Weather Processor@1:2320/107 to wx-storm@lists.illinois.edu on Monday, May 11, 2026 12:15:16
    ACUS01 KWNS 111215
    SWODY1
    SPC AC 111213

    Day 1 Convective Outlook
    NWS Storm Prediction Center Norman OK
    0713 AM CDT Mon May 11 2026

    Valid 111300Z - 121200Z

    ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS FROM THE COASTAL
    CAROLINAS INTO THE FLORIDA PENINSULA...AND ALONG THE CENTRAL GULF
    COAST...

    ...SUMMARY...
    Isolated severe storms with locally damaging wind gusts and hail are
    possible Monday afternoon from the coastal Carolinas into the
    Florida Peninsula, and along the central Gulf Coast.

    ...Carolinas...
    A large upper trough is present today over the eastern states, with
    a weak cold front sagging southward across the Carolinas. Ample
    low-level moisture is present to the south of the front from central
    SC into southeast NC, with dewpoints in the mid 60s. Pockets of
    daytime heating will destabilize this region, with the potential for
    isolated thunderstorm development by early afternoon. Low-level
    winds are veered and relatively weak, limiting frontal convergence
    and shear. A few strong storms may occur with locally gusty winds
    and hail. But the overall threat appears marginal.

    ...Eastern FL...
    Warm/moist conditions are expected today over the FL Peninsula with temperatures over the interior warming into the 90s. Deep westerly
    flow will focus convergence along the east-coast sea-breeze, leading
    to scattered afternoon thunderstorms. Sufficient deep-layer
    vertical shear may result in isolated strong-severe storms producing gusty/damaging winds and hail.

    ...Coastal LA/MS/AL...
    A convectively-aided shortwave trough over east TX will continue to
    track eastward across the central Gulf Coast region today. The
    combination of daytime heating and dewpoints in the mid-upper 60s
    will yield moderate CAPE values, leading to relatively widespread
    afternoon thunderstorms from southeast LA into southern MS/AL.
    Low-level winds are weak and lapse rates are rather weak.
    Nevertheless, cooler temperatures aloft and degree of instability
    will support a risk of occasionally intense cells capable of
    damaging winds and hail.

    ..Hart/Wendt.. 05/11/2026

    $$

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  • From COD Weather Processor@1:2320/107 to wx-storm@lists.illinois.edu on Monday, May 11, 2026 16:32:46
    ACUS01 KWNS 111632
    SWODY1
    SPC AC 111631

    Day 1 Convective Outlook
    NWS Storm Prediction Center Norman OK
    1131 AM CDT Mon May 11 2026

    Valid 111630Z - 121200Z

    ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS FROM THE COASTAL
    CAROLINAS ITO THE EASTERN FLORIDA PENINSULA...AND ACROSS THE CENTRAL
    GULF COAST...

    ...SUMMARY...
    Isolated severe storms with locally damaging wind gusts and hail are
    possible this afternoon from the coastal Carolinas into the Florida
    Peninsula, and along the central Gulf Coast.

    ...Synopsis...
    Upper pattern across the CONUS this morning consists of western
    ridging and eastern troughing. A pair of shortwave troughs are
    embedded within the parent trough, one moving through the middle OH
    Valley and the other farther south across TX. A convectively
    generated vorticity maximum moving across the western Gulf precedes
    the TX shortwave. Farther west, a shortwave trough is moving through
    the northern periphery of the upper ridging over northern MT and
    adjacent southern Saskatchewan.

    Recent surface analysis places a low over the eastern NC/SC border
    vicinity, with a cold front extending southwestward through the
    Southeast and southern AL through the far western Gulf into Deep
    South TX. Another low exists farther northwest over southern
    Saskatchewan, with a cold front extending south-southwestward from
    this low across eastern into south-central MT.

    ...Eastern SC/Far Southern NC...
    Regional radar imagery shows isolated thunderstorms currently
    ongoing near the surface low over the eastern NC/SC border vicinity.
    A modest increase in buoyancy is anticipated ahead of these storms
    over the next few hours. This buoyancy coupled with strong shear
    could result in a few bowing segments capable of damaging gusts.
    Additional isolated thunderstorm development is anticipated late
    this afternoon as the weak cold front moves eastward across SC.
    Moderate buoyancy and shear will support the potential for a few
    more robust/organized updrafts capable of isolated hail and/or
    damaging gusts.

    ...Eastern FL...
    Warm/moist conditions are expected today over the FL Peninsula, with temperatures over the interior warming into the 90s. Deep westerly
    flow will focus convergence along the east-coast sea-breeze, leading
    to scattered afternoon thunderstorms. Sufficient deep-layer vertical
    shear may result in isolated strong-severe storms producing
    gusty/damaging winds and hail.

    ...Northern/eastern ND into eastern SD...
    Despite limited low-level moisture, modest buoyancy may develop late
    this afternoon/early this evening amid cooling mid-level
    temperatures and increasing mid-level moisture. This buoyancy will
    develop atop a deeply mixed boundary layer, supporting the potential
    for strong gusts if any updrafts can deepen/mature. Given the weak
    and elevated nature of the buoyancy, developing a mature updraft
    capable of lightning will be difficult and the current expectation
    is for most of this activity to be shallow and non-lightning
    producing. That being said, gusty surface winds are possible with
    any convection does develop atop the deeply mixed boundary layer.

    ...Coastal LA/MS/AL...
    The convectively generated shortwave trough over the western Gulf
    mentioned in the synopsis (and associated surface low) are expected
    to progress eastward throughout the day, while the stronger
    shortwave trough back across TX also progress east-southeastward. Easterly/southeasterly low-level flow will be maintained north of
    the Gulf low, increasing low-level convergence along the slow-moving
    frontal zone. This convergence will be augmented by ascent attendant
    to the TX shortwave, with numerous showers and thunderstorms likely.
    Poor lapse rates will limit buoyancy, although moderate deep-layer
    shear could support a few deeper, more organized updrafts. Primary
    risk over this area is heavy rain (as noted in the WPC Day 1
    Excessive Rainfall Outlook), but a few water-loaded downbursts
    capable of wind damage are possible as well.

    ..Mosier/Chalmers.. 05/11/2026

    $$

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  • From COD Weather Processor@1:2320/107 to wx-storm@lists.illinois.edu on Monday, May 11, 2026 19:48:18
    ACUS01 KWNS 111948
    SWODY1
    SPC AC 111946

    Day 1 Convective Outlook
    NWS Storm Prediction Center Norman OK
    0246 PM CDT Mon May 11 2026

    Valid 112000Z - 121200Z

    ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS PORTIONS
    OF THE LOWER MISSISSIPPI VALLEY...THE FLORIDA ATLANTIC COAST...AND
    THE CAROLINA COAST...

    ...SUMMARY...
    Isolated severe storms with locally damaging wind gusts and hail are
    possible this afternoon along the Carolina and Florida Atlantic
    coasts as well as portions of the lower Mississippi Valley.

    ...20z Update...
    The previous outlook largely remains on track with only minor
    adjustments made. Risk probabilities were removed across eastern GA
    where latest satellite imagery shows limited vertical development
    within a broad cumulus field, likely owing to poor ascent given very
    weak low-level convergence along a diffuse frontal zone. Latest
    HRRR/RRFS guidance depicts negligible convective signals across this
    region through tonight, suggesting the potential for severe
    thunderstorms is low. Severe wind probabilities were similarly
    trimmed across portions of southern LA where cold outflow associated
    with a residual MCV over the northern Gulf is spreading northward.
    Ahead of this boundary, temperatures warming into the low 80s within
    a moist air mass may still support convection sufficiently deep for
    a localized downburst concern (see MCD #706). Elsewhere, the
    previous forecast (below) remains on track.

    ..Moore.. 05/11/2026

    .PREV DISCUSSION... /ISSUED 1131 AM CDT Mon May 11 2026/

    ...Synopsis...
    Upper pattern across the CONUS this morning consists of western
    ridging and eastern troughing. A pair of shortwave troughs are
    embedded within the parent trough, one moving through the middle OH
    Valley and the other farther south across TX. A convectively
    generated vorticity maximum moving across the western Gulf precedes
    the TX shortwave. Farther west, a shortwave trough is moving through
    the northern periphery of the upper ridging over northern MT and
    adjacent southern Saskatchewan.

    Recent surface analysis places a low over the eastern NC/SC border
    vicinity, with a cold front extending southwestward through the
    Southeast and southern AL through the far western Gulf into Deep
    South TX. Another low exists farther northwest over southern
    Saskatchewan, with a cold front extending south-southwestward from
    this low across eastern into south-central MT.

    ...Eastern SC/Far Southern NC...
    Regional radar imagery shows isolated thunderstorms currently
    ongoing near the surface low over the eastern NC/SC border vicinity.
    A modest increase in buoyancy is anticipated ahead of these storms
    over the next few hours. This buoyancy coupled with strong shear
    could result in a few bowing segments capable of damaging gusts.
    Additional isolated thunderstorm development is anticipated late
    this afternoon as the weak cold front moves eastward across SC.
    Moderate buoyancy and shear will support the potential for a few
    more robust/organized updrafts capable of isolated hail and/or
    damaging gusts.

    ...Eastern FL...
    Warm/moist conditions are expected today over the FL Peninsula, with temperatures over the interior warming into the 90s. Deep westerly
    flow will focus convergence along the east-coast sea-breeze, leading
    to scattered afternoon thunderstorms. Sufficient deep-layer vertical
    shear may result in isolated strong-severe storms producing
    gusty/damaging winds and hail.

    ...Northern/eastern ND into eastern SD...
    Despite limited low-level moisture, modest buoyancy may develop late
    this afternoon/early this evening amid cooling mid-level
    temperatures and increasing mid-level moisture. This buoyancy will
    develop atop a deeply mixed boundary layer, supporting the potential
    for strong gusts if any updrafts can deepen/mature. Given the weak
    and elevated nature of the buoyancy, developing a mature updraft
    capable of lightning will be difficult and the current expectation
    is for most of this activity to be shallow and non-lightning
    producing. That being said, gusty surface winds are possible with
    any convection does develop atop the deeply mixed boundary layer.

    ...Coastal LA/MS/AL...
    The convectively generated shortwave trough over the western Gulf
    mentioned in the synopsis (and associated surface low) are expected
    to progress eastward throughout the day, while the stronger
    shortwave trough back across TX also progress east-southeastward. Easterly/southeasterly low-level flow will be maintained north of
    the Gulf low, increasing low-level convergence along the slow-moving
    frontal zone. This convergence will be augmented by ascent attendant
    to the TX shortwave, with numerous showers and thunderstorms likely.
    Poor lapse rates will limit buoyancy, although moderate deep-layer
    shear could support a few deeper, more organized updrafts. Primary
    risk over this area is heavy rain (as noted in the WPC Day 1
    Excessive Rainfall Outlook), but a few water-loaded downbursts
    capable of wind damage are possible as well.

    $$

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  • From COD Weather Processor@1:2320/107 to wx-storm@lists.illinois.edu on Tuesday, May 12, 2026 00:52:49
    ACUS01 KWNS 120052
    SWODY1
    SPC AC 120050

    Day 1 Convective Outlook
    NWS Storm Prediction Center Norman OK
    0750 PM CDT Mon May 11 2026

    Valid 120100Z - 121200Z

    ...NO SEVERE THUNDERSTORM AREAS FORECAST...

    ...SUMMARY...
    Organized severe thunderstorms are not expected tonight.

    ...Northern Plains into the Upper Midwest...
    Along the northern periphery of an expansive upper ridge over the
    West, a midlevel trough will continue eastward from the northern
    Plains into the upper MS Valley tonight. Ahead of this feature,
    isolated to widely scattered high-based thunderstorms are evolving
    eastward across northern ND -- in the vicinity of an eastward-moving
    surface trough/front. Despite limited buoyancy, a deeply mixed
    boundary layer could favor a couple strong wind gusts before the
    boundary layer nocturnally cools/stabilizes. See MCD #707 for more
    details. Farther east, a strong low-level jet and related warm
    advection preceding the midlevel trough will promote isolated
    elevated thunderstorms across the upper MS Valley into the upper
    Midwest overnight. Weak instability will preclude severe storms.

    ...Central Gulf Coast and Southeast...
    Isolated thunderstorms will spread/develop eastward along an
    west/east-oriented diffuse cold front extending from the central
    Gulf Coast into northern FL tonight. This activity will remain north
    of the moderately unstable air mass over the Gulf. Across parts of
    the eastern and southern FL Peninsula, a few thunderstorms will
    continue through around 03Z along lingering outflow boundaries.
    While locally strong gusts and small hail are possible, the overall
    severe threat appears low.

    ..Weinman/Worster.. 05/12/2026

    $$

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  • From COD Weather Processor@1:2320/107 to wx-storm@lists.illinois.edu on Tuesday, May 12, 2026 05:52:50
    ACUS01 KWNS 120552
    SWODY1
    SPC AC 120551

    Day 1 Convective Outlook
    NWS Storm Prediction Center Norman OK
    1251 AM CDT Tue May 12 2026

    Valid 121200Z - 131200Z

    ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS THE
    FLORIDA PENINSULA AND PARTS OF THE MIDWEST/GREAT LAKES...

    ...SUMMARY...
    Severe storms will be possible at least on an isolated basis across
    parts of the Florida Peninsula today, and potentially parts of the
    Great Lakes to Lower Missouri Valley and south-central Plains late
    this afternoon and early evening.

    ...Florida Peninsula...
    A front will settle southward today in advance of a low-latitude
    shortwave trough crossing the northeast Gulf. A moist and
    potentially unstable environment will exist during the afternoon,
    especially across the central Peninsula where MLCAPE could exceed
    1500 J/kg, although early day clouds and convection near/south of
    the front leads to some uncertainty regarding destabilization
    details. Regardless, storms should steadily increase in coverage and
    intensity through late morning into the afternoon, initially across
    the north-central Peninsula, maximizing toward the east coast,
    although additional storms may move inland from the Gulf.
    Strengthening mid/high-level winds will support upwards of 30-40 kt
    effective shear and fairly long/semi-straight hodographs, which
    could yield some transient supercell structures pending sufficient destabilization. Damaging winds and hail will be possible at least
    on an isolated basis, and a tornado could occur as well,
    particularly near the effective front. A greater confidence in
    destabilization and the possibility of more sustained
    storms/supercells could warrant a Slight Risk upgrade.

    ...Wisconsin/Lake Michigan to south-central Plains...
    A shortwave trough over the Canadian Prairies will dig southeastward
    and amplify toward the Upper Great Lakes through this evening, with
    a cold front moving southeastward across these regions. Low-level
    moisture will be limited near/ahead of the front, but advection may
    be sufficient to counteract mixing to allow surface dewpoints to
    reach the 50s F by late afternoon/early evening.

    In tandem with the strongest forcing for ascent, and in vicinity of
    the surface low/front, isolated to widely scattered development is
    initially expected, and most probable, late in the afternoon/early
    evening across eastern Wisconsin, with additional storms possible
    farther southwest near the front across Illinois/Missouri and
    potentially into southeast Kansas/northeast Oklahoma. Where storms develop/sustain, steep lapse rates and strong west-northwesterly
    flow aloft could yield some severe storms capable of hail/damaging
    wind.

    ...Western Oregon/southern Washington...
    A few stronger storms with gusty winds and/or sub-severe hail could
    develop late in the afternoon and evening regionally in advance an
    upper-level trough approaching the coastal Pacific Northwest.
    Strengthening deep-layer winds and steepening lapse rates could
    plausibly yield some stronger storms, although the potential for sustained/organized severe storms is currently expected to remain
    low.

    ..Guyer/Weinman.. 05/12/2026

    $$

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  • From COD Weather Processor@1:2320/107 to wx-storm@lists.illinois.edu on Tuesday, May 12, 2026 12:00:51
    ACUS01 KWNS 121200
    SWODY1
    SPC AC 121159

    Day 1 Convective Outlook
    NWS Storm Prediction Center Norman OK
    0659 AM CDT Tue May 12 2026

    Valid 121300Z - 131200Z

    ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS OVER PARTS OF
    FLORIDA...AND FROM THE UPPER MISSISSIPPI VALLEY INTO KANSAS....

    ...SUMMARY...
    Severe storms will be possible at least on an isolated basis across
    parts of the Florida Peninsula today, and potentially from southeast
    Kansas into parts of the Great Lakes late this afternoon and early
    evening.

    ...KS to WI...
    A progressive shortwave trough is evident on morning water vapor
    imagery over MN. This feature will track across the Great Lakes
    region through the forecast period, with the associated surface cold
    front sagging into parts of the upper MS Valley. The air mass ahead
    of the front from WI into IL/MO/KS is initially quite dry with
    dewpoints only in the 30s/40s. However, strong southwesterly
    low-level winds will lead to slow moistening/destabilization of the
    pre-frontal air mass with a narrow corridor of MUCAPE around 500
    J/kg expected by late afternoon. Thunderstorm coverage will likely
    be sparse and high-based. However, a few strong/severe storms may
    form - capable of hail and gusty winds into early evening.

    ...FL...
    A moist and moderately unstable air mass remains in place over the
    FL Peninsula today. A well-defined shortwave trough over southern
    AL will track eastward today, resulting in sufficient large scale
    forcing for scattered afternoon thunderstorms. Low-level winds are
    veered, suggesting the most intense cells will be in vicinity of the
    east-coast sea-breeze. A few organized multicell or supercell
    storms are possible, posing a risk of damaging wind gusts and hail.

    ..Hart/Wendt.. 05/12/2026

    $$

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  • From COD Weather Processor@1:2320/107 to wx-storm@lists.illinois.edu on Tuesday, May 12, 2026 16:29:22
    ACUS01 KWNS 121629
    SWODY1
    SPC AC 121627

    Day 1 Convective Outlook
    NWS Storm Prediction Center Norman OK
    1127 AM CDT Tue May 12 2026

    Valid 121630Z - 131200Z

    ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS OVER PARTS OF FLORIDA...PORTIONS OF THE UPPER MIDWEST...AND SOUTHEAST KANSAS INTO
    WESTERN MISSOURI...

    ...SUMMARY...
    Severe storms will be possible at least on an isolated basis across
    parts of the Florida Peninsula today, and potentially from southeast
    Kansas into parts of the Great Lakes late this afternoon and early
    evening.

    ...Florida...
    A very moist airmass is in place across the FL Peninsula today, with
    surface observations showing dewpoints in the low to mid 70s.
    Mesoanalysis estimates MLCAPE is at or above 1500 J/kg for much of
    the peninsula already. A shortwave trough is currently moving into
    the central Gulf Coast vicinity, with continued
    eastward/southeastward progress expected throughout the day. The
    prevailing buoyancy coupled with ascent attendant to this wave will
    result in scattered to numerous thunderstorms. Low-level flow is
    generally weak, but the shift from low-level easterly winds to
    moderate southwesterly aloft is supporting moderate deep-layer
    vertical shear. Some increased shear is possible in the vicinity of
    the east-coast sea-breeze, with the strongest storms anticipated
    near this boundary as a result. The overall expectation is for some
    organized multicells and a few supercells, posing a risk of damaging
    wind gusts and hail, particularly across the east-central portions
    of the peninsula.

    ...Upper Midwest through the Mid MO Valley into southeast
    KS/northeast OK...
    Recent satellite imagery shows a well-defined shortwave trough
    moving through the Upper Midwest towards the Upper Great Lakes.
    Surface analysis places the low associated with this shortwave over
    the northern MN/WI border vicinity, with an attendant cold front
    extending back southwestward through northwest IA,
    southeast/south-central NE, and far northwest KS. A modest
    pre-frontal trough is in place just ahead of this cold front. The
    shortwave trough is forecast to continue eastward, while the cold
    front progresses eastward/southeastward. Northern portion of this
    front (closer to the surface low and parent shortwave) will make
    notably more eastward/southeastward progress than the
    southern/western portion, which will move more gradually
    southeastward.

    Low-level moisture advection is anticipated ahead of the front, but
    with mid 50s dewpoints currently in central OK, the extent and
    quality of this moisture will likely be somewhat limited. Filtered
    heating and mixing could also reduce dewpoints. Even so, dewpoints
    will likely still reach at least the mid 40s across southern WI,
    gradually increasing into the mid 50s across southeast KS/southwest MO/northeast OK. This is expected to be enough moisture to support a
    narrow corridor of modest buoyancy. Strongest ascent will be near
    the surface low and shortwave trough across the Upper/Mid MS Valley,
    supporting higher storm coverage than areas farther southwest. A few
    high-based storms capable of wind damage and isolated hail are
    possible.

    Farther southwest, lower storm coverage is expected, particularly
    from west-central IL into southeast KS. Thunderstorm chances across
    much of this area appear low enough to remove severe probabilities.
    The only exception is over the southeast KS/southwest MO vicinity.
    Here, greater low to mid-level moisture could still support a storm
    or two. Shear is strong enough to support hail with any storms that
    mature.

    ..Mosier/Chalmers.. 05/12/2026

    $$

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  • From COD Weather Processor@1:2320/107 to wx-storm@lists.illinois.edu on Tuesday, May 12, 2026 19:55:55
    ACUS01 KWNS 121955
    SWODY1
    SPC AC 121954

    Day 1 Convective Outlook
    NWS Storm Prediction Center Norman OK
    0254 PM CDT Tue May 12 2026

    Valid 122000Z - 131200Z

    ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS PORTIONS
    OF THE GREAT LAKES...CENTRAL PLAINS AND FLORIDA...

    ...SUMMARY...
    Severe storms remain possible across parts of the Florida Peninsula
    today, and potentially from southeast Kansas into parts of the Great
    Lakes late this afternoon and early evening.

    ...20z Update Great Lakes...
    Afternoon visible imagery shows the cold core of an upper-level
    trough beginning to impinging on modest low-level moisture south of
    a stalled front near the MI/WI border. While moisture and resulting
    buoyancy remain very limited (200-300 J/kg MUCAPE), steep mid-level
    lapse rates and continued heating should support enough
    destabilization for a few storms this afternoon and evening. Hail is
    possible, especially with any storms elevated above the surface
    given fairly strong mid-level flow. Have adjusted 5% hail
    probabilities northward toward the warm front across the MI/WI
    border.

    ...FL...
    Numerous storms are ongoing this afternoon south of an east-west
    oriented baroclinic zone across the FL Peninsula. To the south, the
    environment remains moderately unstable and sheared, which has
    supported a few organized clusters and supercells so far. Hail,
    damaging winds, and a brief tornado remain possible with the
    strongest storms as the boundary is forecast to sag southward
    through tonight. Have removed severe probabilities and trimmed
    thunder behind the boundary where the air mass has stabilized.

    Otherwise, the prior outlooks remains valid with only minor
    adjustments. See the previous discussion for more information.

    ..Lyons.. 05/12/2026

    .PREV DISCUSSION... /ISSUED 1127 AM CDT Tue May 12 2026/

    ...Florida...
    A very moist airmass is in place across the FL Peninsula today, with
    surface observations showing dewpoints in the low to mid 70s.
    Mesoanalysis estimates MLCAPE is at or above 1500 J/kg for much of
    the peninsula already. A shortwave trough is currently moving into
    the central Gulf Coast vicinity, with continued
    eastward/southeastward progress expected throughout the day. The
    prevailing buoyancy coupled with ascent attendant to this wave will
    result in scattered to numerous thunderstorms. Low-level flow is
    generally weak, but the shift from low-level easterly winds to
    moderate southwesterly aloft is supporting moderate deep-layer
    vertical shear. Some increased shear is possible in the vicinity of
    the east-coast sea-breeze, with the strongest storms anticipated
    near this boundary as a result. The overall expectation is for some
    organized multicells and a few supercells, posing a risk of damaging
    wind gusts and hail, particularly across the east-central portions
    of the peninsula.

    ...Upper Midwest through the Mid MO Valley into southeast
    KS/northeast OK...
    Recent satellite imagery shows a well-defined shortwave trough
    moving through the Upper Midwest towards the Upper Great Lakes.
    Surface analysis places the low associated with this shortwave over
    the northern MN/WI border vicinity, with an attendant cold front
    extending back southwestward through northwest IA,
    southeast/south-central NE, and far northwest KS. A modest
    pre-frontal trough is in place just ahead of this cold front. The
    shortwave trough is forecast to continue eastward, while the cold
    front progresses eastward/southeastward. Northern portion of this
    front (closer to the surface low and parent shortwave) will make
    notably more eastward/southeastward progress than the
    southern/western portion, which will move more gradually
    southeastward.

    Low-level moisture advection is anticipated ahead of the front, but
    with mid 50s dewpoints currently in central OK, the extent and
    quality of this moisture will likely be somewhat limited. Filtered
    heating and mixing could also reduce dewpoints. Even so, dewpoints
    will likely still reach at least the mid 40s across southern WI,
    gradually increasing into the mid 50s across southeast KS/southwest MO/northeast OK. This is expected to be enough moisture to support a
    narrow corridor of modest buoyancy. Strongest ascent will be near
    the surface low and shortwave trough across the Upper/Mid MS Valley,
    supporting higher storm coverage than areas farther southwest. A few
    high-based storms capable of wind damage and isolated hail are
    possible.

    Farther southwest, lower storm coverage is expected, particularly
    from west-central IL into southeast KS. Thunderstorm chances across
    much of this area appear low enough to remove severe probabilities.
    The only exception is over the southeast KS/southwest MO vicinity.
    Here, greater low to mid-level moisture could still support a storm
    or two. Shear is strong enough to support hail with any storms that
    mature.

    $$

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  • From COD Weather Processor@1:2320/107 to wx-storm@lists.illinois.edu on Wednesday, May 13, 2026 00:56:58
    ACUS01 KWNS 130056
    SWODY1
    SPC AC 130054

    Day 1 Convective Outlook
    NWS Storm Prediction Center Norman OK
    0754 PM CDT Tue May 12 2026

    Valid 130100Z - 131200Z

    ...NO SEVERE THUNDERSTORM AREAS FORECAST...

    ...SUMMARY...
    Severe storms are unlikely this evening and overnight. However,
    thunderstorms remain possible across Florida, the Great Lakes, and
    the Pacific Northwest.

    ... 01Z Update ...

    All Level 1/Marginal Risks are removed with this update.

    ... Great Lakes Region ...

    Thunderstorms are ongoing across portions of the Upper Great Lakes
    in association with a strong midlevel low moving across the region.
    MUCAPE peaked earlier this afternoon around 500 J/kg and has been
    decreasing with the loss of peak heating and should continue
    overnight. Thus, despite a favorable vertical shear environment, the
    lack of appreciable instability should preclude severe development
    overnight.

    Additional forced convection along the advancing cold front cannot
    be ruled out across portions of Illinois, Indiana, and Ohio.
    However, the lack of appreciable buoyancy precludes the need for
    severe probabilities.


    ... Florida ...

    Ongoing thunderstorms across the eastern Florida Panhandle and
    portions of the Peninsula should continue this evening. Given the
    uncapped, tropical-like environment, additional thunderstorms cannot
    be ruled out overnight. However, with the midlevel wave continuing
    to weaken across northern Florida/southern Georgia overnight,
    vertical shear profiles should also continue to weaken and limit any
    severe potential.


    ... Central Plains ...

    Convergence along the front has been unable to break through the cap
    this afternoon. With the loss of diurnal heating boundary layer
    stabilization should limit the potential for surface-based
    convection and any severe potential. Although elevated showers may
    develop overnight across southeast Kansas, northeast Oklahoma,
    southwest Missouri, and northwest Arkansas, decreasing instability
    should limit even lightning potential.


    ... Pacific Northwest ...

    As a vigorous midlevel trough approaches the Pacific Northwest this
    evening it will take on an increasingly negative tilt. Strong
    deep-layer ascent and increasing midlevel moisture should be
    sufficient for at least a couple of isolated thunderstorms to
    develop. Although forecast soundings indicate a dry sub-cloud layer
    beneath midlevel instability and strong tropospheric flow, the
    overall thunderstorm coverage should remain too low for
    unconditional wind probabilities to be introduced.

    ..Marsh.. 05/13/2026

    $$

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  • From COD Weather Processor@1:2320/107 to wx-storm@lists.illinois.edu on Wednesday, May 13, 2026 06:09:58
    ACUS01 KWNS 130609
    SWODY1
    SPC AC 130608

    Day 1 Convective Outlook
    NWS Storm Prediction Center Norman OK
    0108 AM CDT Wed May 13 2026

    Valid 131200Z - 141200Z

    ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FROM NORTHERN UTAH
    NORTHWARD ACROSS EASTERN IDAHO...WESTERN WYOMING...AND PORTIONS OF
    WESTERN MONTANA...

    ...SUMMARY...
    Scattered severe thunderstorms are possible across portions of the
    northern High Plains Wednesday afternoon and evening. Severe wind
    gusts are the primary hazard.

    ... Synopsis ...

    An amplified, yet progressive, midlevel pattern will exist across
    the US on Wednesday. A vigorous shortwave trough will move east
    across the northern Rockies as a Mexico-to-Canada midlevel ridge
    moves into the central US. Downstream from the ridge, an amplified
    trough will deepen further, developing into a closed low over the
    northern Mid-Atlantic and southern New England region.


    ... Portions of the Great Basin and the Central and Northern Rockies
    ...

    As the potent midlevel shortwave trough moves across the northern
    Rockies an attendant 80-90 knot midlevel jet streak will overspread
    northern portions of the area during the afternoon and evening
    hours. At the same time, a cold front will push east across the
    region leading to scattered convection by mid-to-late afternoon.
    Forecast soundings continue to exhibit inverted-V thermodynamic
    profiles and increasing cloud-layer shear. The result will be fast
    moving storms capable of transporting momentum downward to the
    surface. Additionally, the dry sub-cloud layer will support the
    potential for some dry microburst potential.


    ... Ohio Valley and Central Appalachians ...

    A surface low will move east from Lower Michigan toward northern New
    York, dragging a cold front eastward across the Ohio Valley and
    central Appalachians before ending up near the Atlantic Coast.
    Toward the end of the forecast period, the northern New York surface
    low will redevelop farther southeast along the front near the
    Atlantic Coast.

    Ahead of the front, surface dewpoints should rise into
    low-to-mid-50Fs contributing to weak instability with diurnal
    heating. Thunderstorms should develop across the area during the
    afternoon along the front, with additional thunderstorms possible
    across terrain favored areas across the central Appalachians.
    Sufficient vertical shear beneath a 50 knot midlevel jet and modest
    low-level lapse rates would support a marginal wind threat.


    ... Texas Panhandle into the High Plains of Southern Colorado ...

    Strong diurnal heating beneath the midlevel ridge may be sufficient
    for convective inhibition to erode and isolated thunderstorms to
    develop across terrain favored areas. Very steep lapse rates will
    support a hail and wind threat.

    ..Marsh/Weinman.. 05/13/2026

    $$

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  • From COD Weather Processor@1:2320/107 to wx-storm@lists.illinois.edu on Wednesday, May 13, 2026 11:53:31
    ACUS01 KWNS 131153
    SWODY1
    SPC AC 131151

    Day 1 Convective Outlook
    NWS Storm Prediction Center Norman OK
    0651 AM CDT Wed May 13 2026

    Valid 131300Z - 141200Z

    ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FROM CENTRAL MT
    SOUTHWARD INTO NORTHERN UT...

    ...SUMMARY...
    Scattered thunderstorms capable of damaging wind gusts are possible
    across portions of the northern High Plains and Great Basin this
    afternoon and evening. Other areas of isolated severe wind/hail
    risk occur over the upper Ohio Valley and the Texas Panhandle.

    ...WV/PA/NY...
    A large upper trough is deepening as it tracks southeastward across
    the Great Lakes and Midwest into the Upper Ohio Valley. The
    associated surface cold front is sweeping across OH, and will extend
    from central NY into western PA and northern WV later today. Clouds
    are currently prevalent across this region, but some
    clearing/heating is expected as low-level moisture is transported
    into the area. The result will be narrow corridor of sufficient
    CAPE for thunderstorm development along the front from NY into WV.
    Given the strength of the upper trough and winds aloft, there is
    concern for a few severe storms capable of damaging winds and
    perhaps hail...mainly in the 18-00z period.

    ...Great Basin...
    A second strong and progressive upper trough has moved ashore over
    OR/WA and will spread mid-level height falls and large scale ascent
    across much of the Great Basin and Rockies today and tonight.
    Low-level moisture is very sparse ahead of the system, but pockets
    of strong heating from northern UT into eastern ID/western WY and
    central MT will result in inverted-v profiles and sufficient CAPE
    for isolated charge separation and robust updrafts. CAM solutions
    suggest a risk of high-based fast-moving showers and occasional
    thunderstorms affecting the region, with the risk of severe wind
    gusts.

    ...TX Panhandle...
    A surface dryline will become established over the TX panhandle
    later today, where temperatures will climb well into the 90s.
    Forecast soundings show only modest CAPE and limited risk of
    convective initiation over this area. However, any storm that can
    persist in this environment would conditionally pose a threat of
    damaging wind gusts and large hail. Will maintain the ongoing MRGL
    risk for this conditional risk.

    ..Hart/Wendt.. 05/13/2026

    $$

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  • From COD Weather Processor@1:2320/107 to wx-storm@lists.illinois.edu on Wednesday, May 13, 2026 16:22:31
    ACUS01 KWNS 131622
    SWODY1
    SPC AC 131620

    Day 1 Convective Outlook
    NWS Storm Prediction Center Norman OK
    1120 AM CDT Wed May 13 2026

    Valid 131630Z - 141200Z

    ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FROM CENTRAL MT
    SOUTHWARD INTO NORTHERN UT...

    ...SUMMARY...
    Scattered thunderstorms capable of damaging wind gusts are possible
    from the Great Basin into northern Rockies this afternoon and
    evening. Other areas of isolated severe wind/hail risk may occur
    over the upper Ohio Valley and the Texas Panhandle.

    ...WV/PA/NY...
    Recent surface analysis places a low over northern Lake
    Huron/central Ontario, with a cold front extending back
    southwestward through western OH and western KY. Current satellite
    shows the associated shortwave trough extending from central Ontario
    into the Mid MS Valley. This imagery also shows two embedded
    vorticity maxima, one near the surface low over central Ontario and
    the other farther southwest over IL/IN. This shortwave is expected
    to mature throughout the day, trending towards a more neutral tilt
    by this evening, while also gradually shifting eastward. The
    associated cold front is forecast to shift quickly eastward as well.

    At least scattered clouds will likely persist throughout the day,
    somewhat tempering the overall daytime heating. Even so, modest
    low-level moisture (i.e. dewpoints in the low/mid 50s) ahead of the
    cold front will support a corridor of sufficient buoyancy for
    thunderstorm development ahead of the front from western PA and WV
    eastward across PA and into southern/central NY. Linear forcing
    along the front and relatively modest deep-layer shear will favor a multicellular line segment mode. Potential exists for a few deeper
    updrafts capable of damaging gusts, but the limited heating ahead of
    the front, modest buoyancy, and displacement south and east of the
    stronger low to mid-level flow should keep the overall severe
    potential isolated. A few isolated instances of hail are possible
    early in the convective cycle before the more linear structures
    dominate.

    Recently issued MCD #0710 addresses this area as well.

    ...Great Basin into the northern Rockies...
    Current satellite imagery shows a well-defined, negatively tilted
    shortwave trough progressing across the Pacific Northwest. This wave
    is forecast to continue eastward through ID and MT today. Strong
    heating and deep boundary-layer mixing is expected ahead of this
    wave from the Great Basin into the northern Rockies. At the same
    time, mid-level moisture associated with the wave will advect eastward/northeastward, resulting in large area of deep inverted-v thermodynamic profiles that are also buoyant enough to support
    convection and isolated lightning. Strong mid-level flow will
    accompany the shortwave, with moderate mid-level flow extending
    southward from the primary wave through UT and far western CO.

    Scattered convection is expected as lift associated with the wave
    begins to interact with this destabilizing airmass, likely starting
    around 20/21Z from western MT into northern UT. This convection,
    which should include lightning-producing updrafts, will then spread eastward/northeastward with time. Strong to severe gusts are
    possible across this entire region, with the highest likelihood for
    severe gusts from central/southern ID into central MT where the
    strongest mid-level flow is expected.

    ...TX Panhandle...
    Deep boundary-layer mixing is anticipated across the TX Panhandle
    today, with temperatures climbing into the 90s. Low-level moisture
    advection should result in higher dewpoints across the eastern
    Panhandle, with the resultant dryline acting as a focus for
    convergence and attempts at convective initiation. The overall
    environment does not look conducive for initiation and majority of
    the CAMs do not show storm development. However, any storm that can
    persist in this environment would conditionally pose a threat of
    damaging wind gusts and large hail.

    ..Mosier/Chalmers.. 05/13/2026

    $$

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  • From COD Weather Processor@1:2320/107 to wx-storm@lists.illinois.edu on Wednesday, May 13, 2026 20:01:06
    ACUS01 KWNS 132000
    SWODY1
    SPC AC 131959

    Day 1 Convective Outlook
    NWS Storm Prediction Center Norman OK
    0259 PM CDT Wed May 13 2026

    Valid 132000Z - 141200Z

    ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FOR PARTS OF THE
    GREAT BASIN INTO THE NORTHERN ROCKIES...

    ...SUMMARY...
    Scattered thunderstorms capable of damaging wind gusts remain
    possible from the Great Basin into northern Rockies this afternoon
    and evening. Other areas of isolated severe wind/hail risk may occur
    over the northern Appalachians and the Texas Panhandle.

    ...20Z Update...
    The previous forecast (see below) remains generally on track.
    Thunder and severe probabilities were trimmed over the OH Valley to
    account for the passage of a broken squall line. Thunder
    probabilities were also trimmed over portions of eastern KS and
    immediate surrounding areas, as confidence for organized elevated
    convection along the easternmost edge of a low-level WAA regime
    continues to decrease.

    ..Squitieri.. 05/13/2026

    .PREV DISCUSSION... /ISSUED 1120 AM CDT Wed May 13 2026/

    ...WV/PA/NY...
    Recent surface analysis places a low over northern Lake
    Huron/central Ontario, with a cold front extending back
    southwestward through western OH and western KY. Current satellite
    shows the associated shortwave trough extending from central Ontario
    into the Mid MS Valley. This imagery also shows two embedded
    vorticity maxima, one near the surface low over central Ontario and
    the other farther southwest over IL/IN. This shortwave is expected
    to mature throughout the day, trending towards a more neutral tilt
    by this evening, while also gradually shifting eastward. The
    associated cold front is forecast to shift quickly eastward as well.

    At least scattered clouds will likely persist throughout the day,
    somewhat tempering the overall daytime heating. Even so, modest
    low-level moisture (i.e. dewpoints in the low/mid 50s) ahead of the
    cold front will support a corridor of sufficient buoyancy for
    thunderstorm development ahead of the front from western PA and WV
    eastward across PA and into southern/central NY. Linear forcing
    along the front and relatively modest deep-layer shear will favor a multicellular line segment mode. Potential exists for a few deeper
    updrafts capable of damaging gusts, but the limited heating ahead of
    the front, modest buoyancy, and displacement south and east of the
    stronger low to mid-level flow should keep the overall severe
    potential isolated. A few isolated instances of hail are possible
    early in the convective cycle before the more linear structures
    dominate.

    Recently issued MCD #0710 addresses this area as well.

    ...Great Basin into the northern Rockies...
    Current satellite imagery shows a well-defined, negatively tilted
    shortwave trough progressing across the Pacific Northwest. This wave
    is forecast to continue eastward through ID and MT today. Strong
    heating and deep boundary-layer mixing is expected ahead of this
    wave from the Great Basin into the northern Rockies. At the same
    time, mid-level moisture associated with the wave will advect eastward/northeastward, resulting in large area of deep inverted-v thermodynamic profiles that are also buoyant enough to support
    convection and isolated lightning. Strong mid-level flow will
    accompany the shortwave, with moderate mid-level flow extending
    southward from the primary wave through UT and far western CO.

    Scattered convection is expected as lift associated with the wave
    begins to interact with this destabilizing airmass, likely starting
    around 20/21Z from western MT into northern UT. This convection,
    which should include lightning-producing updrafts, will then spread eastward/northeastward with time. Strong to severe gusts are
    possible across this entire region, with the highest likelihood for
    severe gusts from central/southern ID into central MT where the
    strongest mid-level flow is expected.

    ...TX Panhandle...
    Deep boundary-layer mixing is anticipated across the TX Panhandle
    today, with temperatures climbing into the 90s. Low-level moisture
    advection should result in higher dewpoints across the eastern
    Panhandle, with the resultant dryline acting as a focus for
    convergence and attempts at convective initiation. The overall
    environment does not look conducive for initiation and majority of
    the CAMs do not show storm development. However, any storm that can
    persist in this environment would conditionally pose a threat of
    damaging wind gusts and large hail.

    $$

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  • From COD Weather Processor@1:2320/107 to wx-storm@lists.illinois.edu on Thursday, May 14, 2026 00:50:08
    ACUS01 KWNS 140050
    SWODY1
    SPC AC 140048

    Day 1 Convective Outlook
    NWS Storm Prediction Center Norman OK
    0748 PM CDT Wed May 13 2026

    Valid 140100Z - 141200Z

    ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS OVER MUCH OF
    CENTRAL INTO NORTHEAST MONTANA...

    ...SUMMARY...
    Scattered severe wind gusts remain possible primarily over Montana
    this evening. Isolated strong storms may linger from Virginia into
    southeast Pennsylvania with gusty winds.

    ...MT...
    A shortwave trough and surface cold front will continue to push east
    across MT this evening, with severe wind potential persisting. A
    leading line of storms is moving into northeast MT, with small hail
    along with gusty winds. To the west, other strong convection was
    noted near the cold front, with sporadic fast-moving cells. Very
    strong outflow moving across south-central MT has also resulted in
    measured gusts over 70 kt.

    For more information, see mesoscale discussion
    #0716.

    ...VA into PA...
    A line of thunderstorms continues to push rapidly east into
    southeast PA, into central MD and across northern VA. Though
    instability is limited, this convection is supported by the
    progressive upper trough. Several stations have reported wind gusts
    in the 30-40 kt range, but 00Z soundings suggest a cooling boundary
    layer this evening should limit severe potential.

    ..Jewell.. 05/14/2026

    $$

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  • From COD Weather Processor@1:2320/107 to wx-storm@lists.illinois.edu on Thursday, May 14, 2026 05:08:10
    ACUS01 KWNS 140508
    SWODY1
    SPC AC 140506

    Day 1 Convective Outlook
    NWS Storm Prediction Center Norman OK
    1206 AM CDT Thu May 14 2026

    Valid 141200Z - 151200Z

    ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS OVER PARTS OF
    CENTRAL AND EASTERN KANSAS...

    ...SUMMARY...
    Thunderstorms with hail and severe wind gusts are expected from
    Kansas into western Texas, with isolated overnight activity into
    parts of the lower Missouri/Mid Mississippi Valley.

    ...Synopsis...
    An upper trough will slowly move across the Northeast and Mid
    Atlantic today, with a surface high moving into the eastern CONUS
    with offshore flow across the East Coast. Behind this system,
    shortwave ridging aloft will move toward the MS Valley during the
    day as a progressive shortwave trough affects the central and
    northern Plains. This wave will bring rapid cooling aloft across the
    Dakotas and into the upper MS Valley during the day, with subtle
    height falls extending into the Central Plains.

    While the primary surface low will be over Canada, a secondary low
    is expected to form over western KS by late afternoon, with the
    surface trough extending fully from the TX Panhandle northward into
    Manitoba. Southerly winds across the Plains will aid the development
    of a narrow moist axis from eastern TX into eastern KS and NE during
    the day, with elevated moisture/warmth developing toward the mid MS
    Valley overnight with a 40-50 kt low-level jet.

    ...KS...
    An isolated supercell or two may develop during the late afternoon
    just downstream of the low-level lapse rate plume and near the
    narrow axis of 60s dewpoints near I-35. Surface convergence will not
    be particularly strong, but forecast soundings indicate a narrow
    zone of uncapped and unstable air mass. Steep lapse rates aloft,
    veering winds with height, and 500 mb winds around 30 kt will
    conditionally favor slow-moving supercells producing large hail. If
    moisture quality verifies near the upper end of the guidance, hail
    over 2.00" diameter may occur.

    ...Southern High Plains...
    Strong heating will lead to deep inverted-v profiles across western
    TX including the Panhandles. Relatively cool temperature aloft as
    well as convergence within the surface trough will favor scattered
    high based thunderstorms, with threat of dry microbursts over a
    relatively large zone from the South Plains into southwest KS.

    ...Lower MS/Mid MS Valleys...
    During the evening and overnight, lift associated with a 50+ kt
    southwesterly low-level jet will bring elevated instability eastward
    out of KS and into MO, southern IA an western IL as minimal height
    falls occur. Forecast soundings indicate substantial elevated MUCAPE
    with steep mid/upper lapse rates, thought shear in the cloud-bearing
    layer will be marginal. This should support elevated storms over
    much of northern MO, southern IA and western IL overnight with
    activity spreading southeast. Isolated strong gusts cannot be ruled
    out given the generally dry sub-cloud layer as storms amass.

    ..Jewell.. 05/14/2026

    $$

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  • From COD Weather Processor@1:2320/107 to wx-storm@lists.illinois.edu on Thursday, May 14, 2026 12:02:10
    ACUS01 KWNS 141202
    SWODY1
    SPC AC 141200

    Day 1 Convective Outlook
    NWS Storm Prediction Center Norman OK
    0700 AM CDT Thu May 14 2026

    Valid 141300Z - 151200Z

    ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS THIS EVENING OVER
    PORTIONS OF CENTRAL KANSAS...

    ...SUMMARY...
    Thunderstorms with hail and severe wind gusts are possible from
    Kansas/Missouri into west Texas.

    ...KS...
    An upper ridge is centered over the central/southern Plains this
    morning, but will break down through the forecast period as a series
    of weak shortwave troughs emanate from the Rockies across the
    central Plains. Meanwhile, strong southerly low-level winds will
    develop across TX/OK/KS, aiding in northward return of moisture and considerable destabilization. The western periphery of the
    returning moisture will be noted by a diffuse dryline from western
    KS into western OK, where temperatures will climb into the mid/upper
    90s today.

    By late afternoon, forecast parameters will be quite favorable for
    supercells capable of large hail and damaging winds across much of
    central KS. However, weak large scale forcing and a formidable cap
    to the east of the dryline significantly limits the confidence in
    thunderstorm development/maintenance. Any storm that forms will
    pose a severe risk, but coverage may be very isolated. Have shrunk
    the risk areas, but will maintain the ongoing SLGT for now.

    ...West TX/OK...
    The aforementioned dryline will extend southward across western OK
    into west TX. Hot and dry conditions will develop to the west of
    the dryline, where model consensus suggesting scattered high-based thunderstorms will develop during the afternoon. Forecast soundings
    show near dry-adiabatic low and mid level lapse rates, and
    sufficient CAPE for a risk of dry microbursts or occasional
    multicell clusters capable of damaging winds. This activity is
    likely to struggle as it spreads east of the dryline this evening
    due to a strong capping inversion.

    ..Hart/Wendt.. 05/14/2026

    $$

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  • From COD Weather Processor@1:2320/107 to wx-storm@lists.illinois.edu on Thursday, May 14, 2026 16:23:43
    ACUS01 KWNS 141623
    SWODY1
    SPC AC 141621

    Day 1 Convective Outlook
    NWS Storm Prediction Center Norman OK
    1121 AM CDT Thu May 14 2026

    Valid 141630Z - 151200Z

    ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS THE CENTRAL
    PLAINS AND SOUTHERN HIGH PLAINS...

    ...SUMMARY...
    Thunderstorms with hail and severe wind gusts are possible from
    Kansas/Missouri southwest into west Texas, mainly late this
    afternoon and evening.

    ...Central Plains including Kansas...
    An upper trough over the Canadian Prairies and northern Plains will
    glancingly influence the region later today, along with an embedded
    disturbance or two emerging from the central Rockies early today.
    Surface cyclogenesis will occur across Kansas, while a front spreads east-southeastward across the central High Plains, and low-level
    moisture steadily increases ahead of a dryline.

    Initiation/sustenance of deep convection is mostly likely to
    initially occur late this afternoon through around sunset across
    west-central into southwest Kansas in vicinity of the surface triple
    point, and to a lesser extent, along the southwestward-extending
    dryline. Beneath a stout elevated mixed layer, moderate buoyancy
    with 2000 J/kg MLCAPE is expected across central Kansas, which will
    be coincident with a belt of 35-40 kt mid-level winds/effective
    shear. Where storms do develop, forecast parameters will be quite
    favorable for supercells capable of large hail and damaging winds
    across much of central toward eastern Kansas. Other higher-based
    severe storms are possible south-southwestward along the dryline.

    ...Southern High Plains including OK/TX Panhandles and West TX...
    Widely scattered high-based storms should develop in vicinity of the
    dryline late this afternoon/early evening. Somewhat higher
    probabilities/storm coverage should exist across the Oklahoma/Texas
    Panhandles and Texas South Plains. Various forecast soundings
    regionally near the dryline reflect a hot and very deeply mixed
    peak-heating boundary layer, to upwards of 4-4.5km AGL/500mb, with
    residual CAPE and moderately strong westerlies atop the boundary
    layer. Strong to potentially severe wind gusts will be possible
    where storms develop in this hot/steep lapse rate environment, with
    a diminishing storm intensity through the post-sunset evening hours
    as the boundary layer cools.

    ..Guyer/Chalmers.. 05/14/2026

    $$

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  • From COD Weather Processor@1:2320/107 to wx-storm@lists.illinois.edu on Thursday, May 14, 2026 19:57:42
    ACUS01 KWNS 141957
    SWODY1
    SPC AC 141955

    Day 1 Convective Outlook
    NWS Storm Prediction Center Norman OK
    0255 PM CDT Thu May 14 2026

    Valid 142000Z - 151200Z

    ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PORTIONS OF
    THE CENTRAL AND SOUTHERN HIGH PLAINS...

    ...SUMMARY...
    Thunderstorms with hail and severe wind gusts are possible from
    Kansas/Missouri southwest into west Texas, mainly late this
    afternoon and evening.

    ...20z Update central Plains and mid MS Valley...
    Isolated convection may develop across portions of central KS late
    this afternoon/evening northeast of the effective triple point.
    Low-level moisture continues to rapidly advect northward across
    central KS but deep mixing will likely limit the extent of the more
    robust 60s F dewpoints. With moderate forecast MLCAPE (1500-2000
    J/kg) amid veering wind profiles, isolated, high-based supercells
    remain possible, mainly with a large hail and damaging wind risk.
    Additional storms are also possible later tonight at the terminus of
    a forecast 40-50 kt low-level jet across far eastern KS into MO. It
    remains unclear if these storms will be robustly organized, but some
    risk for hail and damaging winds may exist. Wind and hail
    probabilities were expanded slightly eastward to capture this
    threat.

    ...Southern and central High Plains...
    High-based showers and a few thunderstorms have begun developing and
    should gradually increase in coverage this afternoon. Weak buoyancy
    (500-1000 J/kg MUCAPE) atop a very deep mixed layer is evident on 12
    and 18z area RAOBs supporting the risk for damaging/severe gusts. A
    few stronger high-based storms could also produce marginally severe
    hail across parts of western KS where buoyancy is somewhat better.
    See MCD#718 for additional short term information.

    ..Lyons.. 05/14/2026

    .PREV DISCUSSION... /ISSUED 1121 AM CDT Thu May 14 2026/

    ...Central Plains including Kansas...
    An upper trough over the Canadian Prairies and northern Plains will
    glancingly influence the region later today, along with an embedded
    disturbance or two emerging from the central Rockies early today.
    Surface cyclogenesis will occur across Kansas, while a front spreads east-southeastward across the central High Plains, and low-level
    moisture steadily increases ahead of a dryline.

    Initiation/sustenance of deep convection is mostly likely to
    initially occur late this afternoon through around sunset across
    west-central into southwest Kansas in vicinity of the surface triple
    point, and to a lesser extent, along the southwestward-extending
    dryline. Beneath a stout elevated mixed layer, moderate buoyancy
    with 2000 J/kg MLCAPE is expected across central Kansas, which will
    be coincident with a belt of 35-40 kt mid-level winds/effective
    shear. Where storms do develop, forecast parameters will be quite
    favorable for supercells capable of large hail and damaging winds
    across much of central toward eastern Kansas. Other higher-based
    severe storms are possible south-southwestward along the dryline.

    ...Southern High Plains including OK/TX Panhandles and West TX...
    Widely scattered high-based storms should develop in vicinity of the
    dryline late this afternoon/early evening. Somewhat higher
    probabilities/storm coverage should exist across the Oklahoma/Texas
    Panhandles and Texas South Plains. Various forecast soundings
    regionally near the dryline reflect a hot and very deeply mixed
    peak-heating boundary layer, to upwards of 4-4.5km AGL/500mb, with
    residual CAPE and moderately strong westerlies atop the boundary
    layer. Strong to potentially severe wind gusts will be possible
    where storms develop in this hot/steep lapse rate environment, with
    a diminishing storm intensity through the post-sunset evening hours
    as the boundary layer cools.

    $$

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  • From COD Weather Processor@1:2320/107 to wx-storm@lists.illinois.edu on Friday, May 15, 2026 00:46:17
    ACUS01 KWNS 150046
    SWODY1
    SPC AC 150044

    Day 1 Convective Outlook
    NWS Storm Prediction Center Norman OK
    0744 PM CDT Thu May 14 2026

    Valid 150100Z - 151200Z

    ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS OVER PARTS OF
    EASTERN KANSAS...NORTHWEST TEXAS AND FAR SOUTHWEST OKLAHOMA...

    ...SUMMARY...
    Thunderstorms with hail and severe wind gusts remain possible from Kansas/Missouri southwest into northwest Texas.

    ...Northwest TX into KS and MO...
    Scattered high-based storms persist from northwest TX into far
    western OK and southern KS, with locally severe gusts. This activity
    should generally wane this evening as inhibition increases. Farther
    north into eastern KS, new cells have finally developed near the
    weak wind shift and within the moist axis where dewpoints are near
    60 F. Steep lapse rates aloft as well as deep layer shear near 40 kt
    and an increasing low-level jet will favor cells producing hail over
    1.00" diameter and locally strong gusts this evening. Area 00Z
    soundings show that inhibition will increase over the next several
    hours and may render most storms elevated. However, hail potential
    may persist. Overnight, additional storms remain likely over
    northern MO and into western IL in the warm advection zone as the
    weak upper wave moves across the area. Marginal hail and locally
    strong gusts will be possible.

    ..Jewell.. 05/15/2026

    $$

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  • From COD Weather Processor@1:2320/107 to wx-storm@lists.illinois.edu on Friday, May 15, 2026 06:01:48
    ACUS01 KWNS 150601
    SWODY1
    SPC AC 150600

    Day 1 Convective Outlook
    NWS Storm Prediction Center Norman OK
    0100 AM CDT Fri May 15 2026

    Valid 151200Z - 161200Z

    ...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS OVER MUCH OF
    IOWA...

    ...SUMMARY...
    Severe storms producing damaging winds and large hail are likely
    from Iowa into northeast Kansas. Isolated hail or damaging wind
    gusts are possible over a large area from western Texas into
    Wisconsin and western Illinois.

    ...Synopsis...
    Moderate westerly winds aloft will exist across the northern tier of
    states today, with several waves from the Pacific Northwest to the
    Great Lakes. The feature of interest will move across the Dakotas
    and toward the upper MS Valley late in the day, aiding storm
    development and severity from NE into WI. To the south, a weak
    shortwave trough will move out of NM and into TX, with mid and high
    level flow enhancement along with modest cooling aloft.

    At the surface, low pressure will develop from southwest KS into the
    TX Panhandle, with a front extending into NE, southern MN, and into
    northern WI. Increasing southerly winds during the afternoon and
    evening will bring 60s F dewpoints northward toward these
    boundaries, with scattered severe storms likely late in the day and
    centered near Iowa.

    Farther south, very steep lapse rates and a subtle upper trough
    should again result in widely scattered high-based storms producing
    severe gusts over the southern High Plains.

    ...IA into eastern NE and northeast KS...
    Southerly winds and daytime heating will support moderate
    instability this afternoon near a surface trough which will extend
    from eastern NE into southern MN and northern WI. Dewpoints are
    expected to reach into the lower 60s F, and perhaps approach 65 F
    during the early evening. Meanwhile, midlevel temperatures will be
    cool, resulting in steep lapse rates and robust CAPE profiles.

    Storms are most likely to initiate during the late afternoon near
    the IA/SD border, and extending northeastward into WI and perhaps
    the central MI Upper Peninsula. Large hail will be possible with the
    initial cells, supported by 60 kt deep-layer shear. Hail to 2.00"
    diameter will be possible even into WI.

    Farther south into IA, the deeper theta-e plume and increasing
    low-level jet will enhance the severe wind risk, with an MCS
    expected to develop and move east/southeast across the region.
    Damaging winds with a few gusts over 70 mph are expected. Additional
    clusters of severe storms are expected from southeast NE into
    northeast KS as well, firmly within the low-level theta-e plume with
    maximally deepened moist layer to 700 mb. Shear will not be as
    strong, but the initial development is expected to be robust with
    large hail and damaging wind gusts.

    ...Southwest KS into western Texas...
    Strong heating will yield very deep mixed layers near and south of
    the Panhandles surface low, while midlevel temperatures remain cool
    enough to support instability despite very low dewpoints. Meanwhile,
    the aforementioned shortwave trough will enhance lift late in the
    day. The result will be scattered high-based thunderstorms, with
    severe wind gusts expected. Isolated gusts over 70 mph may occur.
    Cells that develop into southwest TX may contain marginal hail as
    well, with elongated hodographs in the mid to upper levels.

    ..Jewell/Squitieri.. 05/15/2026

    $$

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  • From COD Weather Processor@1:2320/107 to wx-storm@lists.illinois.edu on Friday, May 15, 2026 12:50:51
    ACUS01 KWNS 151250
    SWODY1
    SPC AC 151248

    Day 1 Convective Outlook
    NWS Storm Prediction Center Norman OK
    0748 AM CDT Fri May 15 2026

    Valid 151300Z - 161200Z

    ...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS ACROSS MUCH OF
    IOWA...

    ...SUMMARY...
    Severe thunderstorms capable of producing severe/damaging winds and
    large to very large hail are likely late this afternoon and evening
    across much of Iowa and vicinity. Isolated to scattered severe hail
    and damaging winds are possible over a broader area from parts of
    the southern High Plains to the Upper Midwest.

    ...Central Plains into the Upper Midwest...
    Generally zonal/westerly mid-level flow will persist over the
    northern tier of the U.S. today, with an upper trough/low moving
    slowly eastward over central Canada. At the surface, the primary low
    will remain in northern Ontario, with a trailing cold front
    extending southward into the Upper Midwest and northern/central
    Plains. A secondary surface low will likely exist over southwest
    KS/northwest OK by peak afternoon heating. A dryline will extend
    southward from this low across much of the southern High Plains.

    Current expectations are for robust thunderstorm development along
    the cold front/surface trough from eastern NE into IA to be delayed
    until late afternoon or early evening (around 22-00Z), as
    large-scale ascent will remain weak until a low-amplitude shortwave
    trough embedded within the westerly mid-level flow eventually
    overspreads the surface warm sector. Continued low-level warm/moist
    advection through the day and diurnal heating will contribute to the development of moderate to locally strong instability across this
    region by early evening. While low-level winds are forecast to
    remain fairly modest, enhanced mid/upper-level flow will support
    sufficient deep-layer shear for updraft organization.

    Initial supercells should pose a threat for large to isolated very
    large hail (2+ inches in diameter), before likely quick upscale
    growth this evening across IA supports a risk for mainly scattered severe/damaging winds. Some of these gusts could exceed 75 mph on a
    localized basis given the expectation for an organized cluster and
    ample instability. A tornado or two could also occur this evening as
    low-level shear gradually increases with a strengthening low-level
    jet. Some adjustments have been made to the Slight and Enhanced Risk
    areas based on latest observational trends and short-term guidance.
    Namely, the Slight Risk has been extended northward into parts of
    southeast MN/southwest WI, where some risk for hail-producing
    supercells should exist along/ahead of the front. The Enhanced Risk
    has also been expanded to include more of western IA, as multiple
    supercells may form and eventually congeal into one or more bowing
    clusters through the evening.

    ...Southern High Plains...
    Robust daytime heating will yield a very well-mixed/deep boundary
    layer near/south of the secondary surface low over southwest KS and
    vicinity. Mid-level temperatures will remain cool enough to support
    at least weak instability, even with modest low-level
    moisture/surface dewpoints. A weak mid-level shortwave trough moving
    from the southern Rockies into the southern High Plains will enhance large-scale ascent late in the day. This should support the
    development of high-based thunderstorms, with occasional strong to
    severe wind gusts expected. Isolated gusts of 75+ mph may occur
    given the very deeply mixed boundary layer extending up to around
    500 mb. Cells that develop in west/southwest TX may contain marginal
    hail, with elongated hodographs in mid/upper levels.

    ..Gleason/Bentley.. 05/15/2026

    $$

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  • From COD Weather Processor@1:2320/107 to wx-storm@lists.illinois.edu on Friday, May 15, 2026 16:31:23
    ACUS01 KWNS 151631
    SWODY1
    SPC AC 151629

    Day 1 Convective Outlook
    NWS Storm Prediction Center Norman OK
    1129 AM CDT Fri May 15 2026

    Valid 151630Z - 161200Z

    ...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS ACROSS IOWA...

    ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS THE UPPER
    MIDWEST AND CENTRAL/SOUTHERN PLAINS...

    ...SUMMARY...
    Severe thunderstorms capable of producing severe/damaging winds and
    large to very large hail are likely late this afternoon and evening
    centered across much of Iowa. Isolated to scattered severe hail and
    damaging winds are possible over a broader area from parts of the
    southern High Plains to the Upper Midwest.

    ...Central Plains into the Upper Midwest including Iowa...
    A cyclonically influenced moderately strong belt of westerlies will
    exist over the northern Plains to Upper Midwest and upper Great
    Lakes. The primary surface low will remain in northern Ontario, with
    a trailing cold front extending southward into the Upper Midwest and northern/central Plains. A secondary surface low will exist across
    southwest Kansas and northwest Oklahoma around peak afternoon
    heating, with a dryline extending south-southwestward from this low
    across much of the southern High Plains.

    Continued expectations are for robust thunderstorm development along
    the cold front/surface trough from eastern Nebraska into Iowa to be
    delayed until late afternoon or early evening (around 22-00Z), as
    large-scale ascent will remain weak until a low-amplitude shortwave
    trough embedded within the westerly mid-level flow eventually
    overspreads the surface warm sector. Continued low-level warm/moist
    advection through the day and diurnal heating will contribute to the development of moderate to locally strong instability (2500+ J/kg
    MLCAPE) across this region by early evening. While low-level winds
    are forecast to remain fairly modest, enhanced mid/upper-level flow
    will support sufficient (35-50 kt) deep-layer shear for updraft
    organization.

    Initial supercells should pose a threat for large to isolated very
    large hail (2+ inches in diameter), before likely quick upscale
    growth this evening across Iowa with an increasing potential for
    scattered severe/damaging winds. Some of these gusts could exceed 75
    mph on a localized basis given the expectation for an organized
    cluster and ample instability. A tornado or two could also occur
    this evening as low-level shear gradually increases with a
    strengthening low-level jet.

    ...Southern High Plains...
    While clouds linger at midday, particularly with southward extent
    across west/southwest Texas, robust daytime heating will yield a
    very well-mixed/deep boundary layer near/south of the secondary
    surface low over southwest Kansas/northwest Oklahoma. Mid-level
    temperatures will remain cool enough to support at least weak
    instability, even with modest low-level moisture/surface dewpoints.
    A weak mid-level shortwave trough moving from the southern Rockies
    into the southern High Plains will enhance large-scale ascent late
    in the day. This should support the development of high-based
    thunderstorms, with occasional strong to severe wind gusts expected.
    Latest short-term guidance suggests a more probable zone of thunderstorm-related gust potential may focus across the Texas South
    Plains and Low Rolling Plains. Isolated gusts of 70+ mph may occur
    given the very deeply mixed boundary layer extending up to around
    500 mb. Cells that develop in west/southwest Texas may also contain
    some hail, with elongated hodographs in mid/upper levels.

    ..Guyer/Moore.. 05/15/2026

    $$

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  • From COD Weather Processor@1:2320/107 to wx-storm@lists.illinois.edu on Friday, May 15, 2026 20:00:25
    ACUS01 KWNS 152000
    SWODY1
    SPC AC 151958

    Day 1 Convective Outlook
    NWS Storm Prediction Center Norman OK
    0258 PM CDT Fri May 15 2026

    Valid 152000Z - 161200Z

    ...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS ACROSS PORTIONS
    OF IOWA...

    ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS THE UPPER
    MIDWEST AND CENTRAL/SOUTHERN PLAINS....

    ...SUMMARY...
    Severe thunderstorms capable of producing severe/damaging winds and
    large to very large hail are likely late this afternoon and evening
    centered across much of Iowa. Isolated to scattered severe hail and
    damaging winds are possible over a broader area from parts of the
    southern High Plains to the Upper Midwest.

    ...20z Update Central Plains...
    Several areas of thunderstorm development are expected this
    afternoon and evening across the central Plains and Midwest.
    Moderate instability beneath 40+ kt of mid-level flow will promote a
    mixed mode of supercells and eventually linear clusters. Hail (some
    2+ inches) along with damaging gusts appear likely with the more
    robust supercells initially along the cold front across NE/northern
    KS, and farther north along the warm front into southern MN.
    Eventual upscale growth into one or more linear clusters should
    favor an increase in the threat for damaging gust and a couple
    tornadoes over parts of IA, IL and southern WI this evening.

    ...Eastern NM/CO and the TX/OK Panhandles...
    Initial high-based shower and thunderstorm development is underway
    coincident with very strong heating and the arrival of a weak
    upper-level shortwave trough atop the well-mixed air mass west of
    the dryline. With mixing depths of 4-5 km below modest buoyancy,
    strong to severe gusts are possible with these showers and
    thunderstorms across the southern High Plains. Wind probabilities
    were shifted slightly west. See MCDs #723 and #724 for short term
    information.

    ..Lyons.. 05/15/2026

    .PREV DISCUSSION... /ISSUED 1129 AM CDT Fri May 15 2026/

    ...Central Plains into the Upper Midwest including Iowa...
    A cyclonically influenced moderately strong belt of westerlies will
    exist over the northern Plains to Upper Midwest and upper Great
    Lakes. The primary surface low will remain in northern Ontario, with
    a trailing cold front extending southward into the Upper Midwest and northern/central Plains. A secondary surface low will exist across
    southwest Kansas and northwest Oklahoma around peak afternoon
    heating, with a dryline extending south-southwestward from this low
    across much of the southern High Plains.

    Continued expectations are for robust thunderstorm development along
    the cold front/surface trough from eastern Nebraska into Iowa to be
    delayed until late afternoon or early evening (around 22-00Z), as
    large-scale ascent will remain weak until a low-amplitude shortwave
    trough embedded within the westerly mid-level flow eventually
    overspreads the surface warm sector. Continued low-level warm/moist
    advection through the day and diurnal heating will contribute to the development of moderate to locally strong instability (2500+ J/kg
    MLCAPE) across this region by early evening. While low-level winds
    are forecast to remain fairly modest, enhanced mid/upper-level flow
    will support sufficient (35-50 kt) deep-layer shear for updraft
    organization.

    Initial supercells should pose a threat for large to isolated very
    large hail (2+ inches in diameter), before likely quick upscale
    growth this evening across Iowa with an increasing potential for
    scattered severe/damaging winds. Some of these gusts could exceed 75
    mph on a localized basis given the expectation for an organized
    cluster and ample instability. A tornado or two could also occur
    this evening as low-level shear gradually increases with a
    strengthening low-level jet.

    ...Southern High Plains...
    While clouds linger at midday, particularly with southward extent
    across west/southwest Texas, robust daytime heating will yield a
    very well-mixed/deep boundary layer near/south of the secondary
    surface low over southwest Kansas/northwest Oklahoma. Mid-level
    temperatures will remain cool enough to support at least weak
    instability, even with modest low-level moisture/surface dewpoints.
    A weak mid-level shortwave trough moving from the southern Rockies
    into the southern High Plains will enhance large-scale ascent late
    in the day. This should support the development of high-based
    thunderstorms, with occasional strong to severe wind gusts expected.
    Latest short-term guidance suggests a more probable zone of thunderstorm-related gust potential may focus across the Texas South
    Plains and Low Rolling Plains. Isolated gusts of 70+ mph may occur
    given the very deeply mixed boundary layer extending up to around
    500 mb. Cells that develop in west/southwest Texas may also contain
    some hail, with elongated hodographs in mid/upper levels.

    $$

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  • From COD Weather Processor@1:2320/107 to wx-storm@lists.illinois.edu on Saturday, May 16, 2026 01:00:57
    ACUS01 KWNS 160100
    SWODY1
    SPC AC 160058

    Day 1 Convective Outlook
    NWS Storm Prediction Center Norman OK
    0758 PM CDT Fri May 15 2026

    Valid 160100Z - 161200Z

    ...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS OVER MUCH OF
    IOWA INTO FAR SOUTHWEST WISCONSIN...

    ...SUMMARY...
    Severe thunderstorms capable of producing severe gusts and large
    hail remain likely this evening centered over Iowa. Isolated to
    scattered severe gusts also remain possible over a broader area from
    parts of the southern High Plains to the Upper Midwest.

    ...IA and southern WI into northeast KS/northern MO...
    Several clusters of severe storms are currently ongoing across
    western into northern IA, with other cells into southeast MN. All
    this is occurring near and ahead of a cold front associated with the
    glancing upper wave to the north. Moderate instability has developed
    as lower 60s F dewpoints spread into the area, and effective
    deep-layer shear near 50 kt will continue to support organization
    into an MCS as outflows aggregate. Until then, large damaging hail
    will also be possible. More isolated activity also extends into far
    southeast NE, with other failed attempts at initiation toward far
    northern KS. The increasing southwest low-level jet this evening may
    support additional development later this evening as the 00Z TOP
    sounding remains moist and unstable.

    For more information see mesoscale discussions #0729 and #0730.

    ...Western TX...western OK...southwest KS...
    Scattered high-based storms continue to produce locally severe gusts
    from parts of western TX into western OK. While capping will
    increase this evening, a few more hours of damaging wind threat
    appear likely with the activity moving into northwest TX. Additional
    isolated activity may also develop anywhere from western OK into
    southwest KS as moisture wraps around the surface low and lapse
    rates remain steep.

    ..Jewell.. 05/16/2026

    $$

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  • From COD Weather Processor@1:2320/107 to wx-storm@lists.illinois.edu on Saturday, May 16, 2026 05:37:28
    ACUS01 KWNS 160537
    SWODY1
    SPC AC 160535

    Day 1 Convective Outlook
    NWS Storm Prediction Center Norman OK
    1235 AM CDT Sat May 16 2026

    Valid 161200Z - 171200Z

    ...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS FROM NORTHEAST
    COLORADO INTO WESTERN NEBRASKA AND KANSAS...

    ...SUMMARY...
    Severe storms capable of large hail, wind damage and perhaps a
    couple of tornadoes will be possible this afternoon and evening
    across parts of the central Plains. Scattered thunderstorms will
    also pose potential for strong to severe winds across the lower to
    mid Missouri Valley.

    ...Synopsis...
    An upper trough will develop over the western states today, with
    increasing southwest winds aloft late in the day and overnight
    across the Rockies and into the High Plains. Preceding the western
    trough, a progressive shortwave will move from the Great Lakes and
    into the Northeast, allowing temporary height rises across the upper
    Midwest/MS Valley. Behind this wave, high pressure will bring stable
    conditions into the northern Plains.

    At the surface, low pressure will develop over the central High
    Plains, with a trough extending from eastern WY into western TX.
    Meanwhile, a stalled front will be situated across northeast CO into
    northern KS and toward IA/northern IL, with easterly winds across NE
    and IA. A moist air mass will reside south of this boundary, with
    60s F dewpoints prevalent. Backed winds will help bring this
    moisture westward toward northeast CO and western NE by late
    afternoon as 850 mb winds increase toward evening. Shear profiles
    will thus become increasingly favorable from late afternoon through
    evening for supercells, with large hail, damaging winds and perhaps
    a couple tornadoes from CO into western NE/KS.

    East of there, another concentration of strong to severe storms is
    expected from eastern NE into IA, northern MO and northeast KS near
    the boundary.

    Elsewhere, a broad fetch of 20-30 kt southerly 850 mb winds will
    maintain a moist air mass across the lower to middle MS Valley and
    across the OH Valley. Here, pockets of stronger instability will
    support scattered strong storms during the afternoon.

    ...Central Plains...
    Storms are likely to form near the Front Range after 21Z, with
    activity developing eastward into NE and KS. A few supercells appear
    likely with time, producing damaging hail and severe wind gusts.
    Westerly winds aloft atop the deep low-level easterlies will
    elongate hodographs with over 50 kt effective shear, while SRH
    values favor supercells and severe bows through evening.

    Farther east, strong instability will develop near the east-west
    boundary, with scattered severe storms developing around 21Z. Some
    of these storms may produce hail over 2.00" diameter as lapse rates
    aloft will remain steep, and with ample moisture.

    Additional isolated activity is possible along the dryline from
    southwest KS into the eastern TX Panhandle and western OK. Here,
    shear will be weak but a narrow zone of uncapped air mass with a
    backing dryline may support isolated storms with locally severe hail
    or wind gusts.

    ..Jewell/Squitieri.. 05/16/2026

    $$

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  • From COD Weather Processor@1:2320/107 to wx-storm@lists.illinois.edu on Saturday, May 16, 2026 12:50:02
    ACUS01 KWNS 161249
    SWODY1
    SPC AC 161248

    Day 1 Convective Outlook
    NWS Storm Prediction Center Norman OK
    0748 AM CDT Sat May 16 2026

    Valid 161300Z - 171200Z

    ...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF
    THE CENTRAL HIGH PLAINS...

    ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF
    THE OHIO VALLEY...

    ...SUMMARY...
    Severe thunderstorms capable of producing large to very large hail, severe/damaging winds (some 75+ mph), and a few tornadoes should
    occur this afternoon and evening across parts of the central Plains
    into Iowa.

    ...Synopsis...
    Large-scale upper troughing will gradually amplify over the western
    CONUS today, while modestly enhanced west-southwesterly mid-level
    flow persists over the southern/central Plains. A separate
    mid/upper-level trough with strong westerly mid-level jet will move
    eastward across the Great Lakes and Ontario/Quebec through the day,
    while remaining generally displaced to the north of the surface warm
    sector. At the surface, a weak low over the southern High Plains
    this morning should reform over the central High Plains of eastern
    CO by late afternoon, as large-scale ascent preceding the western
    CONUS upper trough gradually overspreads this region. Greater
    low-level moisture will remain confined along/south of a
    convectively reinforced front from NE/IA into the southern Great
    Lakes region. A dryline will extend southward from this boundary
    across the southern/central High Plains.

    ...Central High Plains to Iowa...
    High-based thunderstorms that initially develop across the higher
    terrain of central CO this afternoon will eventually encounter a
    more unstable airmass in eastern CO/western KS, as low-level
    moisture gradually increases in the bent back region to the
    north/northwest of the surface low. An increase in convective
    coverage and intensity is anticipated as this activity spreads
    eastward across the central High Plains late this afternoon and
    evening, aided by at least moderate instability and deep-layer
    shear. While some supercell potential will exist, along with a
    threat for large to isolated very large hail, most guidance
    continues to suggest that an intense bowing cluster will develop and
    spread eastward along/near the surface boundary across southern
    NE/northern KS through the evening. A greater threat for severe
    winds, some of which could be significant (75+ mph), remains
    apparent, as steep low/mid-level lapse rates aid in efficient
    downward momentum transfer within the convective cluster. A modest
    expansion has been made to the Enhanced Risk to account for the
    potential of a slightly larger cluster.

    A separate area of robust convective development should also occur
    farther east this afternoon/evening across parts of IA and vicinity
    along/near the surface front. This activity will likely be aided by strengthening low-level warm advection this evening, and it may
    persist through much of the night. The presence of steep mid-level
    lapse rates, increasing low-level moisture, and daytime heating all
    suggest that moderate to locally strong instability will likely be
    in place by late afternoon along/south of the front. While westerly
    mid-level flow should only be modestly enhanced, sufficient
    deep-layer shear is forecast to support supercells initially. Large
    to very large hail (isolated 2+ inches) appears possible within the
    first couple hours of initiation, before thunderstorm
    mergers/interactions occur and the overall mode becomes messy. Some
    increase in the severe/damaging wind threat may develop if a more
    organized cluster can emerge and spread east-southeastward through
    the evening and early overnight hours. A few tornadoes also appear
    possible through the evening with any sustained supercells. This
    potential should remain focused along/near the front where backed
    low-level easterly winds may locally enhance 0-1 km SRH.

    ...Southern High Plains...
    Isolated thunderstorms may initiate this afternoon along the surface
    dryline from southwest KS into the eastern OK/TX Panhandles and
    western OK. While deep-layer shear will be weaker with southward
    extent across the southern High Plains, a narrow zone of minimal
    MLCIN along/east of the dryline may support isolated convection
    capable of producing both locally severe hail and wind gusts.

    ...Mid Mississippi Valley into the Midwest/Ohio Valley...
    Scattered to numerous thunderstorms are ongoing this morning from
    central MO into the Midwest/OH Valley. This convection is likely
    being aided by warm/moist advection associated with a
    west-southwesterly low-level jet. While instability remains fairly
    limited at the moment, some potential for occasional gusty winds and
    marginally severe hail should continue through the late morning with
    this activity. Greater destabilization is forecast along/south of
    this ongoing convection across the lower OH Valley this afternoon.
    One or more convectively enhanced MCVs may aid robust thunderstorm
    development across parts of western/central KY, with a threat for
    scattered damaging winds and isolated severe hail. A brief tornado
    or two also appears possible. A Slight Risk has been introduced
    across this area where a more focused risk for damaging winds has
    become apparent in short-term guidance.

    ..Gleason/Bentley.. 05/16/2026

    $$

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  • From COD Weather Processor@1:2320/107 to wx-storm@lists.illinois.edu on Saturday, May 16, 2026 16:32:33
    ACUS01 KWNS 161632
    SWODY1
    SPC AC 161630

    Day 1 Convective Outlook
    NWS Storm Prediction Center Norman OK
    1130 AM CDT Sat May 16 2026

    Valid 161630Z - 171200Z

    ...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF
    THE CENTRAL HIGH PLAINS AND CENTRAL PLAINS...

    ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF
    THE OHIO VALLEY...

    ...SUMMARY...
    Severe thunderstorms capable of producing large to very large hail, severe/damaging winds (some 75+ mph), and a few tornadoes should
    occur this afternoon and evening across parts of the central Plains
    into Iowa.

    ...Central High Plains into Mid MO Valley...
    Recent surface analysis placed a low over southwest KS, with a warm
    front extending through a low over far southeast NE to a third low
    over southern WI. The low over southwest KS is forecast to fill
    while another low develops back farther west across southeast CO
    today. As it does, low-level moisture advection will persist across
    the central Plains, while a deeper upper trough traverses the
    Intermountain West. Combination of low-level convergence east and
    north of the surface low and increasing large-scale ascent will
    favor thunderstorm development during the late afternoon/early
    evening across northeast CO. This initial activity is expected to be supercellular, with large to very large hail as the primary risk.
    This initial activity should be high-based, with strong downdrafts
    resulting in a quick transition to a linear mode. Even so, some
    tornado risk is still apparent, particularly with the southernmost
    supercells that persist through the early evening when a
    strengthening low-level jet will lengthen low-level hodographs
    considerably.

    Most guidance continues to suggest that an intense bowing cluster,
    with significant wind gusts over 75 mph possible, will develop and
    spread eastward along/near the warm front from along the southern
    NE/northern KS border vicinity through the evening. Given the
    organized nature of this line, it should persist throughout most of
    the night, and an eastward expansion has been made to the Enhanced
    Risk to account for increased probability of strong gusts into more
    of southeast NE.

    A separate area of intense thunderstorms is anticipated farther east
    this afternoon/evening along/near the warm front. Given the ongoing thunderstorms across northern MO, there is some question to where
    the front consolidates this afternoon. Consensus within the guidance
    places it from far southeast NE across southern IA, but there is
    some chance it ends up a bit farther south in far northern MO.
    Robust thunderstorm development is expected along this boundary this
    afternoon amid strong low-level moisture advection and heating, and
    persistent low-level convergence. Environmental conditions support
    supercells capable of all severe hazards, including large to very
    large hail (isolated 2"+ inches in diameter) and tornadoes, but a
    messy convective mode and related storm interference could disrupt
    updrafts and may limit discreteness. Tornado risk will be focused
    along/near the front where backed low-level easterly winds may
    locally enhance 0-1 km SRH. Some clustering is possible, with an
    attendant threat for more damaging gusts wherever this clustering
    occurs.

    ...Mid Mississippi Valley into the Midwest/Ohio Valley...
    With the primary shortwave trough well west of the region, mesoscale
    features will dominate the severe potential across the region today.
    One such feature is the MCV currently moving through southeast MO.
    This feature is expected to result in a localized increase in
    mid-level flow along its eastern periphery as it progresses eastward/northeastward along the OH River vicinity. Filtered heating
    and/or outflow from the ongoing showers and thunderstorms could
    result in a baroclinic zone ahead of this vorticity maximum from
    north-central KY into far southern IN. Expectation is that ascent
    attendant to the MCS coupled with low-level convergence along this
    boundary will result in additional thunderstorm development this
    afternoon.

    The locally enhanced mid-level flow coupled with modest low-level
    southerly flow should result in moderate vertical shear, with
    effective bulk shear values from 30 to 40 kt. This is sufficient for
    updraft organization, but the mixed boundary layer will likely
    support strong downdrafts. The general expectation is for an early
    mostly multicell/isolated supercell mode to transition quickly to a
    more linear mode with one or more bowing line segments. Isolated
    hail is possible early in the convective cycle, with a trend towards
    more damaging gusts with time. Given the modest and veered low-level
    flow, the tornado potential will be low, but the presence of a
    boundary suggests that there remains a low-probability tornado risk.


    ...Southern High Plains...
    Isolated thunderstorms may initiate this afternoon along the surface
    dryline from southwest KS into the eastern OK/TX Panhandles and
    western OK. While deep-layer shear will be weaker with southward
    extent across the southern High Plains, a narrow zone of minimal
    MLCIN along/east of the dryline may support isolated convection
    capable of producing both locally severe hail and wind gusts.

    ..Mosier/Bunting.. 05/16/2026

    $$

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  • From COD Weather Processor@1:2320/107 to wx-storm@lists.illinois.edu on Saturday, May 16, 2026 20:01:32
    ACUS01 KWNS 162001
    SWODY1
    SPC AC 161959

    Day 1 Convective Outlook
    NWS Storm Prediction Center Norman OK
    0259 PM CDT Sat May 16 2026

    Valid 162000Z - 171200Z

    ...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS CENTRAL HIGH
    AND CENTRAL PLAINS...

    ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS OVER PARTS OF THE
    LOWER OHIO VALLEY...

    ...SUMMARY...
    Severe thunderstorms capable of producing large to very large hail, severe/damaging winds (some 75+ mph), and a few tornadoes remain
    likely this afternoon and evening across parts of the central Plains
    into Iowa.

    ...20z Update OH valley/Midwest...
    Ahead of several MCVs and outflow from prior convection, ample
    heating is supporting destabilization amid mid to upper 60s F
    surface dewpoints. Scattered thunderstorm development is likely
    across over southern IL/IN into northern KY through this evening.
    Moderate buoyancy and ~30 kt of deep-layer shear will promote a mix
    of organized multicell structures capable of damaging gusts and some
    hail. A tornado or two also remains possible with any stronger
    linear clusters or transient supercells able to become established.
    See MCD#735 for short term information.

    ...Central High Plains to the Mid MO Valley...
    Several foci for strong to severe convection remain apparent this
    afternoon along a broad frontal zone from the Rockies/High Plains to
    the Mid MO Valley. Scattered severe storms are expected this
    afternoon and evening near the intersection of the surface trough
    and stalled front across the mid MO Valley. Moderate to strong
    destabilization and 40+ kt of westerly deep-layer shear will support
    supercell structures with large hail and damaging winds over te mid
    MO Valley. A locally greater tornado risk may develop with any
    sustained supercells across parts of eastern NE and southern IA into
    northern MO where baked low-level flow near a modifying outflow
    boundary intersects with the stalled front.

    Initial convective development within the broad upslope regime
    across the higher terrain of the central Rockies and adjacent High
    Plains should continue to intensify as it moves eastward this
    afternoon/evening encountering progressively stronger buoyancy and
    shear. This will support supercells with large to very large hail,
    damaging gusts and a tornado or two from northeastern CO and
    southwest NE into northwest KS. Upscale growth into one or more
    clusters with a continued severe threat is expected tonight along
    and north of the stationary front across the central Plains. See
    MCD#736 for more information.

    ...Southern Plains...
    A conditional risk for strong thunderstorms remains apparent along
    the dryline late this afternoon/evening across portions of the
    eastern TX Panhandle and western OK. Displaced from the stronger
    deep-layer shear, and likely high based owing the strong low-level
    mixing, predominately multi cell storms are possible amid steep
    mid-level lapse rates and moderate buoyancy (1500-2000 J/kg MLCAPE).
    Confidence in convective initiation remains low but a risk for
    damaging gusts and hail remains possible.

    ..Lyons.. 05/16/2026

    .PREV DISCUSSION... /ISSUED 1130 AM CDT Sat May 16 2026/

    ...Central High Plains into Mid MO Valley...
    Recent surface analysis placed a low over southwest KS, with a warm
    front extending through a low over far southeast NE to a third low
    over southern WI. The low over southwest KS is forecast to fill
    while another low develops back farther west across southeast CO
    today. As it does, low-level moisture advection will persist across
    the central Plains, while a deeper upper trough traverses the
    Intermountain West. Combination of low-level convergence east and
    north of the surface low and increasing large-scale ascent will
    favor thunderstorm development during the late afternoon/early
    evening across northeast CO. This initial activity is expected to be supercellular, with large to very large hail as the primary risk.
    This initial activity should be high-based, with strong downdrafts
    resulting in a quick transition to a linear mode. Even so, some
    tornado risk is still apparent, particularly with the southernmost
    supercells that persist through the early evening when a
    strengthening low-level jet will lengthen low-level hodographs
    considerably.

    Most guidance continues to suggest that an intense bowing cluster,
    with significant wind gusts over 75 mph possible, will develop and
    spread eastward along/near the warm front from along the southern
    NE/northern KS border vicinity through the evening. Given the
    organized nature of this line, it should persist throughout most of
    the night, and an eastward expansion has been made to the Enhanced
    Risk to account for increased probability of strong gusts into more
    of southeast NE.

    A separate area of intense thunderstorms is anticipated farther east
    this afternoon/evening along/near the warm front. Given the ongoing thunderstorms across northern MO, there is some question to where
    the front consolidates this afternoon. Consensus within the guidance
    places it from far southeast NE across southern IA, but there is
    some chance it ends up a bit farther south in far northern MO.
    Robust thunderstorm development is expected along this boundary this
    afternoon amid strong low-level moisture advection and heating, and
    persistent low-level convergence. Environmental conditions support
    supercells capable of all severe hazards, including large to very
    large hail (isolated 2"+ inches in diameter) and tornadoes, but a
    messy convective mode and related storm interference could disrupt
    updrafts and may limit discreteness. Tornado risk will be focused
    along/near the front where backed low-level easterly winds may
    locally enhance 0-1 km SRH. Some clustering is possible, with an
    attendant threat for more damaging gusts wherever this clustering
    occurs.

    ...Mid Mississippi Valley into the Midwest/Ohio Valley...
    With the primary shortwave trough well west of the region, mesoscale
    features will dominate the severe potential across the region today.
    One such feature is the MCV currently moving through southeast MO.
    This feature is expected to result in a localized increase in
    mid-level flow along its eastern periphery as it progresses eastward/northeastward along the OH River vicinity. Filtered heating
    and/or outflow from the ongoing showers and thunderstorms could
    result in a baroclinic zone ahead of this vorticity maximum from
    north-central KY into far southern IN. Expectation is that ascent
    attendant to the MCS coupled with low-level convergence along this
    boundary will result in additional thunderstorm development this
    afternoon.

    The locally enhanced mid-level flow coupled with modest low-level
    southerly flow should result in moderate vertical shear, with
    effective bulk shear values from 30 to 40 kt. This is sufficient for
    updraft organization, but the mixed boundary layer will likely
    support strong downdrafts. The general expectation is for an early
    mostly multicell/isolated supercell mode to transition quickly to a
    more linear mode with one or more bowing line segments. Isolated
    hail is possible early in the convective cycle, with a trend towards
    more damaging gusts with time. Given the modest and veered low-level
    flow, the tornado potential will be low, but the presence of a
    boundary suggests that there remains a low-probability tornado risk.


    ...Southern High Plains...
    Isolated thunderstorms may initiate this afternoon along the surface
    dryline from southwest KS into the eastern OK/TX Panhandles and
    western OK. While deep-layer shear will be weaker with southward
    extent across the southern High Plains, a narrow zone of minimal
    MLCIN along/east of the dryline may support isolated convection
    capable of producing both locally severe hail and wind gusts.

    $$

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  • From COD Weather Processor@1:2320/107 to wx-storm@lists.illinois.edu on Sunday, May 17, 2026 01:03:05
    ACUS01 KWNS 170103
    SWODY1
    SPC AC 170100

    Day 1 Convective Outlook
    NWS Storm Prediction Center Norman OK
    0800 PM CDT Sat May 16 2026

    Valid 170100Z - 171200Z

    ...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS ACROSS NORTHERN
    KANSAS AND SOUTHERN NEBRASKA...

    ...SUMMARY...
    Severe thunderstorms capable of producing large hail,
    severe/damaging winds (some 75+ mph), and a couple tornadoes remain
    possible tonight, especially across southern Nebraska and northern
    Kansas.

    ...01z Update - Central Plains/Missouri Valley...
    Primary scenario this evening will be an upscale-growing/organizing
    cluster of storms across northern Kansas and southern Nebraska. A
    bit more spatial room has been given (southward adjusted) across
    northern Kansas (mostly north of I-70) for what may still be a
    post-01z increasing damaging wind potential, including
    significant-caliber wind gusts across northern Kansas and far
    southern Nebraska, aside from a lingering broad regional potential
    for some large hail as well. Measured 85 mph gusts have recently
    been reported near Colby, Kansas.

    ..Guyer.. 05/17/2026

    $$

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  • From COD Weather Processor@1:2320/107 to wx-storm@lists.illinois.edu on Sunday, May 17, 2026 06:12:08
    ACUS01 KWNS 170612
    SWODY1
    SPC AC 170610

    Day 1 Convective Outlook
    NWS Storm Prediction Center Norman OK
    0110 AM CDT Sun May 17 2026

    Valid 171200Z - 181200Z

    ...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS ACROSS THE
    CENTRAL PLAINS/MIDDLE MISSOURI VALLEY...

    ...SUMMARY...
    Severe storms are expected this afternoon into tonight across the
    central Plains to the Upper Midwest. Supercells with very large hail
    and strong tornadoes are possible, before one or more linear
    clusters of storms leads to an increase in wind-damage potential by
    evening.

    ...Colorado/Central Plains to Upper Midwest...
    An active severe-weather day is expected regionally. A consequential late-evening/overnight MCS and related outflow across
    Nebraska/northern Kansas to southern Iowa and northern Missouri will
    likely be a lingering factor for later today. For one, this includes
    some southeastward regional adjustment in severe probabilities
    across areas such as eastern Nebraska/western Iowa and northeast
    Kansas/far northwest Missouri.

    One or more embedded disturbances will emerge this afternoon from
    the central Rockies amid increasingly prevalent cyclonic flow aloft
    in advance of an amplifying large-scale trough over the West. Lee
    cyclogenesis will occur across the central High Plains, with a
    northward advection of moisture, and post-MCS-related air mass
    recovery across eastern portions of Kansas/Nebraska into Iowa
    through late afternoon in association with a warm front, and ahead
    of a southeast-progressing cold front across the north-central High
    Plains.

    Initial thunderstorm development is expected across northeast
    Colorado into southwest Nebraska within a low-level upslope flow
    regime ahead of the approaching synoptic cold front. These storms
    will be capable of large hail given very steep lapse rates, strong
    vertical shear and elongated/straight hodographs.

    By late afternoon/early evening, quickly intensifying deep
    convection is expected farther east within the warm sector and near
    and east/northeast of a surface triple point across parts of eastern
    Nebraska and far southeast South Dakota/northwest Iowa, initially
    including intense supercells capable of very large hail and
    tornadoes, some of which could be strong. Backed low-level winds
    within the warm sector, veering with height, will contribute to
    increasing low-level SRH and favorably curved low-level hodographs.
    While the corridor for discrete supercells will be narrow, partly
    due to capping as well as the advancing cold front resulting in
    upscale growth, the expectation is for a few supercells capable of
    producing strong tornadoes and large to very large hail, with a
    somewhat longer duration for more discrete storms with southward
    extent across eastern Nebraska into northeast Kansas.

    With time, one or more linear/bowing segments is expected to develop
    near the east/southeast-advancing cold front and as the low-level
    jet significantly increases during the evening. An attendant risk of
    severe wind gusts will accompany this activity. The severe risk will
    diminish with time and eastward extent during the nighttime hours as instability weakens and capping increases.

    ...Kansas/Oklahoma and North Texas...
    While there are some uncertainties related to capping, particularly
    with southward extent, at least isolated high-based convection is
    expected regionally late in the afternoon, particularly for the
    Kansas and western Oklahoma/eastern Texas Panhandle portion of the
    dryline. Given very steep low to mid-level lapse rates, moderate
    instability, and supercell-supportive wind profiles, large to very
    large hail and strong/severe wind gusts will be possible.

    ...Northern Illinois and Wisconsin to Lower Michigan...
    While the influences of the early morning MCS across the Corn Belt
    are not certain, potentially including lingering cloud cover, there
    is some potential for at least isolated strong/severe storm
    development near the northward-shifting warm front. This could
    potentially include a few supercells and related hazards through the afternoon/early evening.

    ...Southeast/Florida Peninsula...
    On the western periphery of the western Atlantic anticyclone,
    diurnally maximized thunderstorm development should focus from the
    southern Appalachians across Georgia and interior/western Florida
    Peninsula. Thermodynamic environment should be supportive of
    strong/locally severe storms capable of wind damage/downbursts, and
    possibly some hail.

    ..Guyer/Squitieri.. 05/17/2026

    $$

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  • From COD Weather Processor@1:2320/107 to wx-storm@lists.illinois.edu on Sunday, May 17, 2026 12:52:39
    ACUS01 KWNS 171252
    SWODY1
    SPC AC 171250

    Day 1 Convective Outlook
    NWS Storm Prediction Center Norman OK
    0750 AM CDT Sun May 17 2026

    Valid 171300Z - 181200Z

    ...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF
    THE CENTRAL PLAINS AND MID MISSOURI VALLEY...

    ...SUMMARY...
    Severe thunderstorms are expected this afternoon into tonight across
    parts of the southern/central Plains to the Upper Midwest.
    Supercells with very large hail and strong tornadoes are possible
    initially this afternoon, before one or more bowing clusters leads
    to a greater threat for severe/damaging winds this evening.

    ...Synopsis...
    Large-scale upper troughing over the western CONUS should further
    amplify today as an embedded mid-level jet and associated shortwave
    trough move from the West Coast to the Four Corners region through
    the period. A broad zone of around 40-50 kt southwesterly mid-level
    flow will persist today from the southern/central High Plains to the
    Upper Midwest, with multiple small-scale perturbations forecast to
    advance northeastward across these regions. At the surface, a low
    over western KS this morning is expected to gradually develop
    northeastward towards the KS/NE border vicinity this evening. A
    dryline trailing from this low will mix eastward through late
    afternoon peak heating across the southern/central High Plains. A
    warm front will attempt to lift northward today across NE/IA into
    southeast SD and parts of southern MN, while a cold front is
    forecast to gradually advance southeastward across the
    northern/central Plains through the period.

    ...Southern/Central Plains into the Upper Midwest...
    Initial thunderstorm development appears likely across eastern CO
    this afternoon in a low-level upslope flow regime. This activity
    will likely become supercellular and capable of producing large to
    very large hail given the presence of steep mid-level lapse rates,
    strong deep-layer shear, and moderate instability. By 20-22Z,
    additional robust convection is expected to develop along/near the
    cold front across north-central NE/south-central SD in a rapidly
    destabilizing airmass. There is still some uncertainty with how far
    north the warm front and related rich low-level moisture will reach
    across the northern Plains/Upper Midwest, especially given ongoing
    convection and related outflow this morning across NE/IA.

    Still, an increasing large hail threat remains evident with any
    convection that develops along/near the cold front this afternoon,
    as ample MUCAPE and strong deep-layer shear will support organized
    updrafts, including supercells initially. A strong tornado threat
    will exist with any of these supercells that can become/remain
    surface based, as low-level shear strengthens through the late
    afternoon/early evening. A greater threat for severe/damaging winds
    should develop as convection quickly grows upscale into bowing
    clusters this evening. The northeastward extent of this severe wind
    threat remains a bit uncertain, especially into southern/central MN
    where the warm front is forecast to reach. A risk for embedded QLCS
    tornadoes may continue with the surface-based portion of the
    cluster.

    Thunderstorm initiation farther south along the length of the
    dryline appears somewhat conditional given modest large-scale
    ascent. But, most guidance continues to show at least isolated
    high-based convection developing by late afternoon across parts of north-central KS southward into the eastern TX Panhandle/western OK.
    Any thunderstorms which can be sustained will pose a threat for
    large to very large hail and tornadoes, especially across KS where a
    40-50 kt southerly low-level jet will enhance 0-1 km shear. A strong
    tornado appears possible this evening with any supercell that can
    persist, although there should be a tendency for upscale growth into
    a severe wind producing cluster with time as the cold front
    overtakes the dryline.

    ...Great Lakes/Lower Michigan...
    Recent radar and visible satellite imagery show an MCV associated
    with earlier convection across the central Plains is present over IA
    this morning. This feature is forecast to track east-northeastward
    today, and should approach eastern WI and Lower MI by late
    afternoon/early evening. Modest enhancement to the low/mid-level
    wind field should exist in close proximity to this MCV, and the
    surface warm front is expected to gradually develop northward across
    these regions through the day. Some intensification of convection is
    possible this afternoon/evening along and near the warm front, with
    sufficient instability and shear to support a mix of supercells and
    multicell clusters capable of producing damaging winds, hail, and
    perhaps a tornado. A Slight Risk has been added for parts of Lower
    MI given increased confidence in this scenario occurring.

    ...Southeast...
    On the western periphery of a surface high centered over the western
    Atlantic, diurnally maximized thunderstorm development should focus
    from the southern Appalachians across GA and the interior/western FL
    Peninsula. Even though deep-layer shear will remain weak, a
    favorable thermodynamic environment with steepened low-level lapse
    rates should support strong to pulse-severe type convection capable
    of producing isolated wind damage/downbursts and perhaps marginally
    severe hail.

    ...Central and North Texas/ArkLaTex/Lower Mississippi Valley...
    A fairly robust cap is expected to remain across the southern extent
    of the warm sector today, with minimal/nebulous large-scale ascent
    over the southern Plains. Still, some guidance suggests elevated
    thunderstorms may develop through peak afternoon heating across
    parts of northeast TX into the ArkLaTex/lower MS Valley in a
    persistent low-level warm advection regime. If this occurs, then
    isolated severe hail and damaging winds would be possible given the
    strong MUCAPE forecast.

    ...Mid-Atlantic...
    Mid-level ridging should build over the Mid-Atlantic through the
    afternoon, which should tend to suppress most convection. However, a
    weak mid-level perturbation noted in water vapor imagery this
    morning over OH may support isolated convective development this
    afternoon across parts of MD/PA and vicinity. The overall
    environment does not appear overly favorable for organized severe thunderstorms, but gusty winds could occur with any of the stronger
    cores that may develop.

    ..Gleason/Marsh.. 05/17/2026

    $$

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  • From COD Weather Processor@1:2320/107 to wx-storm@lists.illinois.edu on Sunday, May 17, 2026 16:31:15
    ACUS01 KWNS 171631
    SWODY1
    SPC AC 171629

    Day 1 Convective Outlook
    NWS Storm Prediction Center Norman OK
    1129 AM CDT Sun May 17 2026

    Valid 171630Z - 181200Z

    ...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF
    THE CENTRAL PLAINS AND MID MISSOURI VALLEY...

    ...SUMMARY...
    Severe thunderstorms are expected this afternoon into tonight across
    parts of the southern/central Plains to the Upper Midwest.
    Supercells with very large hail and strong tornadoes are possible
    initially this afternoon, before one or more bowing clusters leads
    to a greater threat for severe/damaging winds this evening.

    ...Synopsis...
    12Z soundings across the central and southern Plains reveal steep
    mid-level lapse rates (8.8 deg C per km at OUN, SGF, and TOP) atop
    returning low-level moisture (100 mb mean mixing ratios of 15.4 and
    13.1 g/kg at OUN and FWD, respectively). An MCV, from overnight
    storms across the Plains, is progressing into northern IL/southern
    MN. 12Z DVN sounding sampled a corridor of 50 kt at the base of this
    MCV.

    Morning surface analysis reveals an intricate surface pattern across
    the High Plains/Plains, with multiple lows within the lee troughing
    that extends from eastern MT through the central High Plains, a pair
    of warm fronts, and a residual outflow boundary across NE. The
    deepest surface low is over the far southern CO/KS border vicinity,
    with a warm front extending east-northeastward, roughly along the 70
    deg F isotherm. A dryline also extends southward from this low into
    far west TX. Another low is in place farther north over western NE.
    Another warm front, this one along a sharp gradient in low-level
    moisture, extends northeastward from this low into far southeast SD
    before arcing more eastward across far southern MN and continuing
    across from southern WI into central Lower MI. The aforementioned
    outflow also extends eastward from this low across central NE.

    All of these boundaries will likely influence the severe potential
    today, combining with an emerging upper trough and moderate to
    strong instability, to support an expansive and complex scenario
    today.

    ...Central Plains into the Upper Midwest...
    Expectation is for the northern warm front mentioned in the synopsis
    to continue northward throughout the day while as cold front sweeps southeastward across SD and NE. Thunderstorm development is
    anticipated as the cold front interacts with the returning low-level
    moisture. Moderate to strong buoyancy (i.e. MLCAPE from 2000 to 3000
    J/kg) will support robust thunderstorms from southeast SD through
    south-central NE, potentially as far south as central KS. This
    activity along the front will become linear quickly with damaging
    gusts as the primary risk. Some cell-in-line structures could
    support large to very large hail, particularity early in the
    convective cycle.

    Within this larger area of severe wind and hail potential, two areas
    appear to have a greater tornado threat. One is from
    northeast/east-central NE into far southeast SD. Here, the influence
    of a residual outflow boundary could support more discrete
    development ahead of the front. Any discrete development in the warm
    sector would likely be supercellular and capable of all hazards,
    including very large hail (over 2.5") and a strong tornado. The
    other area is where the convective line interacts with the warm
    front amid a strengthening low-level jet, likely far northern IA/far
    southern MN. Here, increased low-level shear coupled with
    augmentation from interaction with the front could result in
    significant severe gusts as well as lined-embedded QLCS tornadoes.

    ...Central High Plains...
    Thunderstorm development still appears likely across northeastern CO
    this afternoon in a low-level upslope flow regime. This activity
    will likely become supercellular and capable of producing large to
    very large hail given the presence of steep mid-level lapse rates,
    strong deep-layer shear, and moderate instability. Just how far
    east/northeast (into central NE) thunderstorms remains strong is a
    question of timing. Earlier storms could interact with the front as
    it moves through NE, potential leading to persistence or
    reintensification. However, later timing would take these storms
    into central NE behind the cold front. Steep mid-level lapse rates
    in place could still support these storms for a few hours, but the
    overall intensity will likely gradually decrease.

    ...Southern WI into Lower MI...
    An MCV is current progressing into northern IL/southern MN. Modest
    buoyancy and moderate deep-layer shear will support isolated
    elevated thunderstorms capable of small hail and locally strong wind
    gusts through early afternoon. This MCV is expected to continue
    northeastward into Lower MI, potentially interacting with a warm
    front moving north across the region this afternoon. 12Z DVN
    sounding sampled enhanced mid-level flow with this MCV, which could
    result in enough shear to support organized convection along and
    near the warm front later this afternoon/evening. Strong multicells
    and an isolated supercell or two could occur, with an attendant risk
    for damaging winds, hail, and perhaps a tornado.

    ...South-Central KS into the eastern TX Panhandle and western OK...
    Some guidance continues to show at least isolated high-based
    convection developing by late afternoon across parts of
    north-central KS southward into the eastern TX Panhandle/western OK.
    Any thunderstorms which can be sustained would likely be
    supercellular and capable of all severe hazards, including large to
    very large hail and tornadoes. Increasing low-level shear after 00Z
    supports a conditional risk for a strong tornado.

    -- No changes to these areas from the earlier 13Z Outlook --

    ...Southeast...
    On the western periphery of a surface high centered over the western
    Atlantic, diurnally maximized thunderstorm development should focus
    from the southern Appalachians across GA and the interior/western FL
    Peninsula. Even though deep-layer shear will remain weak, a
    favorable thermodynamic environment with steepened low-level lapse
    rates should support strong to pulse-severe type convection capable
    of producing isolated wind damage/downbursts and perhaps marginally
    severe hail.

    ...Central and North Texas/ArkLaTex/Lower Mississippi Valley...
    A fairly robust cap is expected to remain across the southern extent
    of the warm sector today, with minimal/nebulous large-scale ascent
    over the southern Plains. Still, some guidance suggests elevated
    thunderstorms may develop through peak afternoon heating across
    parts of northeast TX into the ArkLaTex/lower MS Valley in
    persistent low-level warm advection regime. If this occurs, then
    isolated severe hail and damaging winds would be possible given the
    strong MUCAPE forecast.

    ...Mid-Atlantic...
    Mid-level ridging should build over the Mid-Atlantic through the
    afternoon, which should tend to suppress most convection. However, a
    weak mid-level perturbation noted in water vapor imagery this
    morning over OH may support isolated convective development this
    afternoon across parts of MD/PA and vicinity. The overall
    environment does not appear overly favorable for organized severe thunderstorms, but gusty winds could occur with any of the stronger
    cores that may develop.

    ..Mosier/Chalmers.. 05/17/2026

    $$

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  • From COD Weather Processor@1:2320/107 to wx-storm@lists.illinois.edu on Sunday, May 17, 2026 20:03:41
    ACUS01 KWNS 172003
    SWODY1
    SPC AC 172002

    Day 1 Convective Outlook
    NWS Storm Prediction Center Norman OK
    0302 PM CDT Sun May 17 2026

    Valid 172000Z - 181200Z

    ...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF
    THE CENTRAL PLAINS AND MID MISSOURI VALLEY...

    ...SUMMARY...
    Severe thunderstorms are expected this afternoon into tonight across
    parts of the southern/central Plains to the Upper Midwest.
    Supercells with very large hail and strong tornadoes are possible
    initially this afternoon, before one or more bowing clusters leads
    to a greater threat for severe/damaging winds this evening.

    ...20z Update portions of the northern MO Valley and Midwest...
    Earlier elevated convection across southern SD has gradually
    strengthened into a broader convective complex ahead of the cold
    front this afternoon. Current expectations are for this cluster, and
    additional supercells to evolve near the synoptic warm front near
    the SD/NE/IA and MN borders this afternoon/evening. Strongly backed
    low-level flow will support a tornado risk with a mixed convective
    mode before upscale growth into an MCS/bowing cluster this evening.
    Thereafter, a significant damaging wind threat with a few embedded
    tornadoes may evolve along the warm frontal corridor across northern
    IA and southern MN tonight. Damaging wind probabilities have been
    increased ahead of this cluster.

    Farther south, a CIG2 tornado area was considered across eastern NE
    and west-central IA given the presence of STP 4-7 possibly
    overlapping with discrete supercells. However, numerous storms are
    expected ahead of the cold front with expected interactions casting
    uncertainty on the longevity of the more discrete storms.
    Regardless, a volatile thermodynamic and kinematic environment (RAP
    ESRH 300-400 m2/s2) could support the threat for a higher-end
    tornado this evening across southeastern NE and southwestern IA
    should supercells remain more discrete.

    ...Southern OK and North TX...
    Modest ascent from a subtropical jet over portions of TX could
    support isolated thunderstorm development in the Red River Vicinity
    to central TX this evening. A broadly unstable environment with 70s
    F surface dewpoints of sufficient bulk shear for supercells could
    support some hail or damaging wind risk with any convection able to
    develop. Confidence in this scenario remains very low.

    ...Central High Plains...
    Air mass destabilization is ongoing in the post-frontal upslope flow
    regime across the central High Plains. Supercells remain likely with
    large hail, damaging gusts and a tornado or two. Eventually one or
    more clusters may evolve and spread eastward with an increased risk
    for damaging gusts tonight. Higher probabilities were shifted
    southward slightly to better align with the observed cold frontal
    position.

    Else where the outlook remains unchanged, see the previous
    discussion.

    ..Lyons.. 05/17/2026

    .PREV DISCUSSION... /ISSUED 1129 AM CDT Sun May 17 2026/

    ...Synopsis...
    12Z soundings across the central and southern Plains reveal steep
    mid-level lapse rates (8.8 deg C per km at OUN, SGF, and TOP) atop
    returning low-level moisture (100 mb mean mixing ratios of 15.4 and
    13.1 g/kg at OUN and FWD, respectively). An MCV, from overnight
    storms across the Plains, is progressing into northern IL/southern
    MN. 12Z DVN sounding sampled a corridor of 50 kt at the base of this
    MCV.

    Morning surface analysis reveals an intricate surface pattern across
    the High Plains/Plains, with multiple lows within the lee troughing
    that extends from eastern MT through the central High Plains, a pair
    of warm fronts, and a residual outflow boundary across NE. The
    deepest surface low is over the far southern CO/KS border vicinity,
    with a warm front extending east-northeastward, roughly along the 70
    deg F isotherm. A dryline also extends southward from this low into
    far west TX. Another low is in place farther north over western NE.
    Another warm front, this one along a sharp gradient in low-level
    moisture, extends northeastward from this low into far southeast SD
    before arcing more eastward across far southern MN and continuing
    across from southern WI into central Lower MI. The aforementioned
    outflow also extends eastward from this low across central NE.

    All of these boundaries will likely influence the severe potential
    today, combining with an emerging upper trough and moderate to
    strong instability, to support an expansive and complex scenario
    today.

    ...Central Plains into the Upper Midwest...
    Expectation is for the northern warm front mentioned in the synopsis
    to continue northward throughout the day while as cold front sweeps southeastward across SD and NE. Thunderstorm development is
    anticipated as the cold front interacts with the returning low-level
    moisture. Moderate to strong buoyancy (i.e. MLCAPE from 2000 to 3000
    J/kg) will support robust thunderstorms from southeast SD through
    south-central NE, potentially as far south as central KS. This
    activity along the front will become linear quickly with damaging
    gusts as the primary risk. Some cell-in-line structures could
    support large to very large hail, particularity early in the
    convective cycle.

    Within this larger area of severe wind and hail potential, two areas
    appear to have a greater tornado threat. One is from
    northeast/east-central NE into far southeast SD. Here, the influence
    of a residual outflow boundary could support more discrete
    development ahead of the front. Any discrete development in the warm
    sector would likely be supercellular and capable of all hazards,
    including very large hail (over 2.5") and a strong tornado. The
    other area is where the convective line interacts with the warm
    front amid a strengthening low-level jet, likely far northern IA/far
    southern MN. Here, increased low-level shear coupled with
    augmentation from interaction with the front could result in
    significant severe gusts as well as lined-embedded QLCS tornadoes.

    ...Central High Plains...
    Thunderstorm development still appears likely across northeastern CO
    this afternoon in a low-level upslope flow regime. This activity
    will likely become supercellular and capable of producing large to
    very large hail given the presence of steep mid-level lapse rates,
    strong deep-layer shear, and moderate instability. Just how far
    east/northeast (into central NE) thunderstorms remains strong is a
    question of timing. Earlier storms could interact with the front as
    it moves through NE, potential leading to persistence or
    reintensification. However, later timing would take these storms
    into central NE behind the cold front. Steep mid-level lapse rates
    in place could still support these storms for a few hours, but the
    overall intensity will likely gradually decrease.

    ...Southern WI into Lower MI...
    An MCV is current progressing into northern IL/southern MN. Modest
    buoyancy and moderate deep-layer shear will support isolated
    elevated thunderstorms capable of small hail and locally strong wind
    gusts through early afternoon. This MCV is expected to continue
    northeastward into Lower MI, potentially interacting with a warm
    front moving north across the region this afternoon. 12Z DVN
    sounding sampled enhanced mid-level flow with this MCV, which could
    result in enough shear to support organized convection along and
    near the warm front later this afternoon/evening. Strong multicells
    and an isolated supercell or two could occur, with an attendant risk
    for damaging winds, hail, and perhaps a tornado.

    ...South-Central KS into the eastern TX Panhandle and western OK...
    Some guidance continues to show at least isolated high-based
    convection developing by late afternoon across parts of
    north-central KS southward into the eastern TX Panhandle/western OK.
    Any thunderstorms which can be sustained would likely be
    supercellular and capable of all severe hazards, including large to
    very large hail and tornadoes. Increasing low-level shear after 00Z
    supports a conditional risk for a strong tornado.

    -- No changes to these areas from the earlier 13Z Outlook --

    ...Southeast...
    On the western periphery of a surface high centered over the western
    Atlantic, diurnally maximized thunderstorm development should focus
    from the southern Appalachians across GA and the interior/western FL
    Peninsula. Even though deep-layer shear will remain weak, a
    favorable thermodynamic environment with steepened low-level lapse
    rates should support strong to pulse-severe type convection capable
    of producing isolated wind damage/downbursts and perhaps marginally
    severe hail.

    ...Central and North Texas/ArkLaTex/Lower Mississippi Valley...
    A fairly robust cap is expected to remain across the southern extent
    of the warm sector today, with minimal/nebulous large-scale ascent
    over the southern Plains. Still, some guidance suggests elevated
    thunderstorms may develop through peak afternoon heating across
    parts of northeast TX into the ArkLaTex/lower MS Valley in
    persistent low-level warm advection regime. If this occurs, then
    isolated severe hail and damaging winds would be possible given the
    strong MUCAPE forecast.

    ...Mid-Atlantic...
    Mid-level ridging should build over the Mid-Atlantic through the
    afternoon, which should tend to suppress most convection. However, a
    weak mid-level perturbation noted in water vapor imagery this
    morning over OH may support isolated convective development this
    afternoon across parts of MD/PA and vicinity. The overall
    environment does not appear overly favorable for organized severe thunderstorms, but gusty winds could occur with any of the stronger
    cores that may develop.

    $$

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  • From COD Weather Processor@1:2320/107 to wx-storm@lists.illinois.edu on Monday, May 18, 2026 01:09:49
    ACUS01 KWNS 180109
    SWODY1
    SPC AC 180107

    Day 1 Convective Outlook
    NWS Storm Prediction Center Norman OK
    0807 PM CDT Sun May 17 2026

    Valid 180100Z - 181200Z

    ...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS ACROSS THE
    CENTRAL PLAINS/MIDDLE MISSOURI VALLEY...

    ...SUMMARY...
    Severe thunderstorms will continue tonight especially across Kansas
    into far eastern Nebraska and Iowa, northwest Missouri and southern
    Minnesota. This includes an increasing evening-time potential for
    damaging winds aside from continued tornado and large hail risks
    regionally.

    ...Central/southern Plains to Upper Midwest...
    General regional trends will be for ongoing storms to continue to
    grow upscale with increasing damaging wind potential this evening.
    However, tornado potential (including a few strong) will continue
    with embedded/semi-discrete supercells this evening, including near
    the southern Minnesota warm frontal vicinity, and farther
    south-southwest across far eastern Nebraska/western Iowa and
    northeast Kansas and northwest Missouri, and perhaps with southern
    peripheral development near the dryline across southern Kansas.
    Scenario is supported by a moist/unstable air mass, along with
    dramatically strengthening south-southwesterly winds in the lowest
    2-3 km AGL, a trend already noted in regional WSR-88D VWP data as
    supplemental to 00z observed soundings from Omaha/Topeka/Norman and Springfield, Missouri.

    ..Guyer.. 05/18/2026

    $$

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  • From COD Weather Processor@1:2320/107 to wx-storm@lists.illinois.edu on Monday, May 18, 2026 05:56:49
    ACUS01 KWNS 180556
    SWODY1
    SPC AC 180555

    Day 1 Convective Outlook
    NWS Storm Prediction Center Norman OK
    1255 AM CDT Mon May 18 2026

    Valid 181200Z - 191200Z

    ...THERE IS A MODERATE RISK OF SEVERE THUNDERSTORMS ACROSS EASTERN/SOUTH-CENTRAL KANSAS AND SOUTHEAST NEBRASKA/FAR NORTHWEST
    MISSOURI...

    ...SUMMARY...
    Numerous severe thunderstorms are expected this afternoon and
    evening across the south-central Plains and Middle Missouri Valley.
    Supercells capable of very large hail and strong to intense
    tornadoes are most likely from central Kansas and southeast Nebraska
    into Iowa and northwest Missouri.

    ...Central Plains and Midwest...
    A regional outbreak of severe storms, potentially including
    strong/intense tornadoes (EF2/EF3+), is expected across the central
    Plains during the late afternoon and evening, although some
    uncertainties persist regarding the upper-end magnitude/spatial
    details of the heightened tornado potential. An extensive MCS exists
    early in the overnight from eastern/central Iowa southwestward into northeast/central Kansas, where regenerative/repetitive storms
    persist.

    This MCS should weaken/lose integrity through the early morning,
    although convection may regenerate and intensify again along
    composite outflow, eastward across the middle Mississippi Valley and
    lower Ohio Valley and potentially parts of the Great Lakes within a destabilizing air mass this afternoon. Damaging winds should be the
    most probable risk, although some tornado and hail potential will
    exist as well.

    The western fringe of this remnant cold pool will modify early today
    with a steady northward flux of low-level moisture, with a very
    unstable environment unfolding by mid/late afternoon across south-central/eastern Kansas into far west/northwest Missouri and
    Iowa/far southeast Nebraska. As a shortwave trough/speed max emerges
    from the central Rockies, deep convective development is expected
    along the initially stalled or slow-moving
    northeast/southwest-oriented front across central/northeast Kansas
    and southeast Nebraska and western Iowa by late afternoon.

    This increasingly rich low-level moisture will reside beneath an
    elevated mixed layer characterized by 8-9 C/km mid-level lapse
    rates, resulting in MLCAPE 3000-4000 J/kg. Mass response to the
    ejecting wave, along with a northeastward-translating 60-70 kt
    mid-level jet, and a significantly strengthening low-level jet by
    sunset, will yield increasingly favorable wind profiles for intense
    supercells capable of very large hail and tornadoes. This may
    includes strong and potentially intense tornadoes (EF2/EF3+). That
    said, the duration of a semi-discrete storm mode remains a key
    question, given the parallel orientation of the stalled front and
    the deep-layer shear vectors, and that the front will trend more southeastward-progressive during the evening. Thus, the
    strong/potentially intense tornado threat will peak prior to upscale
    growth into line segments along the front, with severe outflow gusts
    and embedded circulations becoming the main concerns over time
    tonight as storms progress east-southeastward across the Lower
    Missouri Valley and middle Mississippi Valley.

    ...Oklahoma and western North Texas...
    Storm development along the dryline across western Oklahoma into
    western North Texas/Lower Rolling Plains is more uncertain given
    more limited forcing for ascent. If/where storms do form, there is
    the potential for very large hail and a conditional risk for
    tornadoes. A consistently forecast flow weakness above 400 mb
    by late afternoon/evening does not appear favorable for particularly
    long-lived storms if they do form.

    ...Mid-Atlantic/Northeast States...
    Influenced by terrain and a surface trough, isolated strong to
    locally severe storms capable of wind damage could occur this
    afternoon within a moderately unstable environment.

    ..Guyer/Squitieri.. 05/18/2026

    $$

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  • From COD Weather Processor@1:2320/107 to wx-storm@lists.illinois.edu on Monday, May 18, 2026 12:46:17
    ACUS01 KWNS 181246
    SWODY1
    SPC AC 181244

    Day 1 Convective Outlook
    NWS Storm Prediction Center Norman OK
    0744 AM CDT Mon May 18 2026

    Valid 181300Z - 191200Z

    ...THERE IS A MODERATE RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF CENTRAL/NORTHEAST KANSAS...SOUTHEAST NEBRASKA...AND FAR NORTHWEST
    MISSOURI...

    ...SUMMARY...
    Numerous severe thunderstorms are expected this afternoon and
    evening across the south-central Plains and mid Missouri Valley.
    Supercells capable of producing very large to giant hail and
    multiple strong to intense tornadoes are most likely from central
    Kansas and southeast Nebraska into Iowa and northwest Missouri.

    ...Central Plains into the Midwest/Great Lakes...
    Extensive convection continues this morning from western IL into MO
    and far eastern KS, aided by warm/moist advection associated with a
    40-50 kt southwesterly low-level jet. Gradual destabilization of the
    airmass downstream of this ongoing activity is expected today across
    the mid MS Valley and Midwest/OH Valley/Great Lakes. Some potential
    exists for re-intensification of one or more bowing clusters, with
    scattered damaging winds the main concern as low-level lapse rates
    gradually steepen. Somewhat less instability and more modest
    mid-level flow and related deep-layer shear with eastward extent
    into the OH Valley should induce gradual weakening with these
    clusters this evening.

    The outflow boundary from the morning convection across KS will
    likely play a key role in determining the northern extent of
    appreciable severe risk later today across the central Plains into
    the mid MO Valley. There is concern that this boundary's continued
    southward movement this morning and ongoing convection to its north
    may hinder/delay destabilization this afternoon ahead of the surface
    cold front/dryline. Still, strengthening mid-level flow and
    large-scale ascent associated with an ejecting shortwave trough is
    expected to overspread the developing warm sector across central KS
    into southeast NE by mid to late afternoon.

    Even with potential limiting factors such as outflow boundary
    placement and residual cloud cover, the presence of very steep lapse
    rates aloft (reference 12Z DDC observed sounding) and daytime
    heating of a rather moist low-level airmass will likely support
    strong to possibly extreme instability south of the cold front and
    east of the dryline by early afternoon. Most guidance continues to
    suggest that robust thunderstorm initiation will occur by 18-22Z
    across central/northeast KS into far southeast NE. These initial
    supercells should pose a threat for very large to potentially giant
    hail (2-4+ inches in diameter). As low-level shear gradually
    increases through late afternoon/early evening in tandem with a
    strengthening southerly low-level jet, a focused spatial/temporal
    corridor for strong to intense tornadoes should exist across parts
    of central/northeast KS into far southeast NE and northwest MO.

    Fairly quick upscale growth appears likely by mid to late evening as thunderstorm mergers/interactions occur, and as the cold front
    advances east-southeastward. Even so, a continued threat for QLCS
    and embedded supercell tornadoes should continue, as low-level shear
    will remain enhanced by a 50+ kt low-level jet. Severe/damaging
    winds will also become an increasing concern as convection spreads
    eastward in tandem with the cold front. Some severe wind threat may
    persist through much of the night since ample instability is
    forecast to exist ahead of convection, especially across KS/MO/OK.

    ...Southern Plains...
    Thunderstorm initiation along the dryline this afternoon/early
    evening across western OK into western north TX is more uncertain
    than locations farther north given expectations for more limited
    forcing for ascent. If/where convection does form, there is the
    potential for very large hail and a conditional risk for tornadoes
    with any persistent supercells, given the presence of steep
    mid-level lapse rates, strong instability, moderate deep-layer
    shear, and gradually increasing low-level shear this evening. But,
    weaker winds above 400 mb by late afternoon/evening may not be
    overly favorable for long-lived convection, even if it does form.

    ...Mid-Atlantic/Northeast...
    Influenced by terrain and a surface trough, isolated strong to
    severe thunderstorms capable of producing occasional wind damage may
    occur this afternoon within a moderately unstable environment.

    ..Gleason/Marsh.. 05/18/2026

    $$

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  • From COD Weather Processor@1:2320/107 to wx-storm@lists.illinois.edu on Monday, May 18, 2026 16:26:52
    ACUS01 KWNS 181626
    SWODY1
    SPC AC 181625

    Day 1 Convective Outlook
    NWS Storm Prediction Center Norman OK
    1125 AM CDT Mon May 18 2026

    Valid 181630Z - 191200Z

    ...THERE IS A MODERATE RISK OF SEVERE THUNDERSTORMS THIS AFTERNOON
    AND EVENING OVER PARTS OF EASTERN KANSAS...SOUTHEAST
    NEBRASKA...NORTHWEST MISSOURI...AND SOUTHWEST IOWA....

    ...SUMMARY...
    Numerous severe thunderstorms are expected this afternoon and
    evening across the south-central Plains and mid Missouri Valley.
    Supercells capable of producing very large to giant hail and
    multiple strong to intense tornadoes are most likely from central
    Kansas and southeast Nebraska into Iowa and northwest Missouri.

    ...Central Plains...
    Morning water vapor loop shows a potent shortwave trough rotating
    across the central Rockies into western KS. The primary surface
    boundary extends from western IA into central KS, with a pronounced
    outflow boundary associated with overnight convection extending from
    southeast KS into southern MO. The outflow boundary will lift
    northward today, allowing a very moist and extremely unstable air
    mass to spread into eastern KS/northwest MO/extreme southeast
    NE/southwest IA. This is the area most concerning for intense
    supercells later today.

    Initial storms are expected to develop by early afternoon near the
    triple point of the retreating outflow boundary and cold front.
    These storms will track northeastward through the afternoon and
    early evening in a strongly sheared environment favorable for
    tornadoes, very large hail, and damaging winds. It remains unclear
    how stormscale interactions will impact discrete supercell mode, but
    strong tornadoes are a concern in this region.

    Farther southwest, thunderstorms will develop in vicinity of the
    cold front across south-central KS by late afternoon. Recent CAM
    solutions suggest these storms may be affected by the linear frontal
    forcing, and may be slightly anafrontal. This would lessen the
    tornado risk, but very large hail and damaging winds would remain a
    concern. No changes have been made to the Moderate Risk area due to conflicting model signals.

    ...Western OK/Northwest TX...
    Full sunshine will lead to hot temperatures along the dryline over
    western OK into northwest TX. At least isolated thunderstorms are
    expected to form in this area, with a risk of large hail and
    damaging winds. Weak large scale forcing may limit storm duration
    and intensity.

    ...OH Valley/Great Lakes...
    A line of thunderstorms along the IL/IN border is tracking
    northeastward into a warm/moist air mass. Relatively strong
    low-level wind fields and steep low-level lapse rates suggest a
    continued risk of scattered wind damage with the strongest storms as
    they track across parts of IN/Lower MI/Northwest OH.

    ..Hart/Halbert.. 05/18/2026

    $$

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  • From COD Weather Processor@1:2320/107 to wx-storm@lists.illinois.edu on Monday, May 18, 2026 20:06:51
    ACUS01 KWNS 182006
    SWODY1
    SPC AC 182005

    Day 1 Convective Outlook
    NWS Storm Prediction Center Norman OK
    0305 PM CDT Mon May 18 2026

    Valid 182000Z - 191200Z

    ...THERE IS A MODERATE RISK OF SEVERE THUNDERSTORMS OVER PORTIONS OF
    CENTRAL AND NORTHEASTERN KANSAS...FAR SOUTHEASTERN
    NEBRASKA...NORTHWESTERN MISSOURI...AND FAR SOUTHWESTERN IOWA....

    ...SUMMARY...
    Numerous severe thunderstorms are expected this afternoon and
    evening across the south-central Plains and mid Missouri Valley.
    Supercells capable of producing very large to giant hail and
    multiple strong to intense tornadoes remain likely from central
    Kansas and southeast Nebraska into Iowa and northwest Missouri.

    ...20z Update Midwest Lower Great Lakes...
    An expansive MCS remains ongoing over portions of the lower Great
    Lakes this afternoon. The environment ahead of the complex is
    unstable, but with gradually decreasing moisture/buoyancy farther
    east. An isolated severe risk likely exists ahead of the line across
    OH and lower MI through this evening.

    A large cold pool behind the complex has overturned the air mass
    across much of northern IL, southern WI and eastern IA. This should
    greatly limit air mass recovery this afternoon and evening.
    Additional convection originating from the central Plains and mid MO
    valley may continue eastward, but is forecasted to weaken as it
    encounters the cooler air mass tonight. Isolated storms, likely
    elevated, could persist with a risk for hail, but the severe
    potential has decreased such that, probabilities were lowered.

    ...Central Plains and Mid MO Valley...
    Several supercells and organized clusters have emerged across parts
    of KS and southern NE. A very unstable and strongly sheared
    environment remains in place ahead of these storms. This should
    support a risk for all hazards, include strong tornadoes, very large
    hail, and significant damaging winds. Current expectations are for
    the individual supercells to grow upscale into one or more clusters
    as they interact with a modifying outflow boundary across northeast
    KS and northwestern MO. While the environment becomes gradually less
    unstable farther north and east, very strong shear will likely
    support a continued risk for all hazards this evening. The western
    portions of the risk area has been trimmed in parts of central KS
    where the cold front has sagged southward.

    ...Southwest TX..
    Strong diurnal heating along southern portions of the dryline has
    resulted in isolated storm development this afternoon. Very large
    buoyancy (MLCAPE 3000-4000 J/kg) and steep lapse rates will likely
    continue to support high-based isolated storms. Vertical shear is
    marginal, but sufficient for supercells with hail and damaging wind
    potential. Have extended severe probabilities southward along the
    dryline.

    ..Lyons.. 05/18/2026

    .PREV DISCUSSION... /ISSUED 1125 AM CDT Mon May 18 2026/

    ...Central Plains...
    Morning water vapor loop shows a potent shortwave trough rotating
    across the central Rockies into western KS. The primary surface
    boundary extends from western IA into central KS, with a pronounced
    outflow boundary associated with overnight convection extending from
    southeast KS into southern MO. The outflow boundary will lift
    northward today, allowing a very moist and extremely unstable air
    mass to spread into eastern KS/northwest MO/extreme southeast
    NE/southwest IA. This is the area most concerning for intense
    supercells later today.

    Initial storms are expected to develop by early afternoon near the
    triple point of the retreating outflow boundary and cold front.
    These storms will track northeastward through the afternoon and
    early evening in a strongly sheared environment favorable for
    tornadoes, very large hail, and damaging winds. It remains unclear
    how stormscale interactions will impact discrete supercell mode, but
    strong tornadoes are a concern in this region.

    Farther southwest, thunderstorms will develop in vicinity of the
    cold front across south-central KS by late afternoon. Recent CAM
    solutions suggest these storms may be affected by the linear frontal
    forcing, and may be slightly anafrontal. This would lessen the
    tornado risk, but very large hail and damaging winds would remain a
    concern. No changes have been made to the Moderate Risk area due to conflicting model signals.

    ...Western OK/Northwest TX...
    Full sunshine will lead to hot temperatures along the dryline over
    western OK into northwest TX. At least isolated thunderstorms are
    expected to form in this area, with a risk of large hail and
    damaging winds. Weak large scale forcing may limit storm duration
    and intensity.

    ...OH Valley/Great Lakes...
    A line of thunderstorms along the IL/IN border is tracking
    northeastward into a warm/moist air mass. Relatively strong
    low-level wind fields and steep low-level lapse rates suggest a
    continued risk of scattered wind damage with the strongest storms as
    they track across parts of IN/Lower MI/Northwest OH.

    $$

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  • From COD Weather Processor@1:2320/107 to wx-storm@lists.illinois.edu on Tuesday, May 19, 2026 01:06:56
    ACUS01 KWNS 190106
    SWODY1
    SPC AC 190105

    Day 1 Convective Outlook
    NWS Storm Prediction Center Norman OK
    0805 PM CDT Mon May 18 2026

    Valid 190100Z - 191200Z

    ...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF
    FAR NORTHERN OKLAHOMA...SOUTHERN AND EASTERN KANSAS INTO NORTHWEST MISSOURI...FAR SOUTHEAST NEBRASKA AND SOUTH-CENTRAL IOWA...

    ...SUMMARY...
    Numerous severe thunderstorms are expected this evening from the
    southern and central Plains into the mid Missouri Valley. Supercells
    and bowing line segments capable of producing severe wind gusts,
    tornadoes and large hail remain likely from eastern and southern
    Kansas into far southeast Nebraska, Iowa and northwest Missouri.

    ...Southern and Central Plains/Mid Missouri Valley...
    At the synoptic level, multiple shortwave troughs are ejecting
    northeastward across the central U.S. early this evening. A 50 to 70
    knot mid-level jet is translating northeastward across the central
    Plains, with a 40 to 50 knot low-level jet in place from northern
    Oklahoma into eastern Kansas and western Missouri. A squall-line is
    ongoing along the western edge of the low-level jet, and this line
    will move east-southeastward across the remainder of eastern Kansas
    into western Missouri this evening into tonight. Ahead of the line,
    strong instability is analyzed by the RAP with MLCAPE in the 3000 to
    4000 J/kg range. This, combined with strong large-scale ascent to
    the southeast of the mid-level jet, and moderate deep-layer shear
    evident on regional WSR-88D VWPs, will continue to support a severe
    threat with this line for the remainder of the evening. Severe wind
    gusts with be likely along the leading edge of the line. Large hail
    and tornadoes will also be possible with rotating elements embedded
    in the line.

    Further north-northeast into northeast Kansas, northwest Missouri
    and south-central Iowa, several semi-discrete supercells are
    ongoing. The Kansas City WSR-88D has 0-3 km storm-relative helicity
    near 475 ms/s2, which appears representative of the environment
    ahead of these storms. For this reason, a potential will continue
    for strong tornadoes over the next few hours. These supercells will
    also be capable of producing large hail and severe wind gusts.

    The squall-line will gradually move east-southeastward into the
    lower Missouri Valley and Ozarks from late this evening into the
    overnight period. The severe threat will become less widespread as
    relatively weaker instability is encountered later tonight.

    ...Southern Plains...
    At the surface, a 997 mb low is located over far northwestern
    Oklahoma, with a dryline extending southward across far western
    Oklahoma into west Texas. To the east of the dryline, the RAP has
    MLCAPE in the 3000 to 4000 J/kg range. Near the axis of the
    strongest instability, a few storms are ongoing across southwest
    Oklahoma, but weakening has recently occurred. Redevelopment will be
    possible later this evening. The strong instability combined with
    moderate deep-layer shear and steep low to mid-level lapse rates
    would support a threat for large hail and severe wind gusts, if
    cells can re-intensify. An isolated tornado threat will also be
    possible if a supercell could develop. Thunderstorms are expected to
    increase in coverage over much of Oklahoma during the overnight
    period, as a cold front moves southward. However, the severe threat
    should become more isolated tonight as instability gradually
    decreases across the region.

    ..Broyles.. 05/19/2026

    $$

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  • From COD Weather Processor@1:2320/107 to wx-storm@lists.illinois.edu on Tuesday, May 19, 2026 05:44:57
    ACUS01 KWNS 190544
    SWODY1
    SPC AC 190543

    Day 1 Convective Outlook
    NWS Storm Prediction Center Norman OK
    1243 AM CDT Tue May 19 2026

    Valid 191200Z - 201200Z

    ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FROM PARTS OF THE
    SOUTHERN PLAINS INTO THE MID MISSISSIPPI VALLEY...AND LOWER GREAT
    LAKES...

    ...SUMMARY...
    Widely scattered severe thunderstorms will be possible today from
    the southern Plains northeastward into the mid Mississippi Valley
    and lower Great Lakes. Damaging winds and hail will be the primary
    threats. A greater threat for large hail is expected in the southern
    High Plains.

    ...Ozarks/Mid Mississippi and Ohio Valleys/Lower Great Lakes...
    At mid-levels today, a shortwave trough and an associated 75 to 90
    knot jet streak will move northeastward into the upper Mississippi
    Valley. At the surface, a cold front will advance southeastward
    through the lower Missouri Valley and Great Lakes. Along and ahead
    of the front, surface dewpoints will mostly be in the mid to upper
    60s F. This will contribute to the development of moderate
    instability over much of the pre-frontal airmass. Increasing
    low-level convergence near the front and warming surface
    temperatures will support scattered thunderstorm development by
    afternoon. Along much of the front, 0-6 km shear is forecast to be
    between 25 to 35 knots, suggesting that enough shear will be present
    for organized storms. The potential for severe wind gusts will be
    greatest along the leading edge of line segments that form in areas
    that heat up the most. The severe threat is expected to persist into
    the evening.

    ...Southern Plains...
    A mid-level shortwave trough will move northeastward into the
    southern High Plains today. Ahead of the trough, a moist and
    unstable airmass will be located over much of the southern Plains
    with surface dewpoints the upper 60s and lower 70s F. In response to
    surface heating, moderate instability will develop over much of the
    moist sector, with MLCAPE likely peaking in the 3000 to 4000 J/kg
    range in many areas. Increasing low-level convergence near the front
    will lead to thunderstorm development during the afternoon. The
    greatest convective coverage is forecast across west-central and
    north-central Texas, where low-level flow will be maximized. Ahead
    of the developing storms, forecast soundings by late afternoon show
    moderate deep-layer shear and steep mid-level lapse rates. This
    environment will support a potential for supercells with large hail,
    mainly with cells in the stronger instability that can remain
    discrete. A threat for severe wind gusts is also expected, with this
    threat increasing if a cold pool can organize during the late
    afternoon or evening. The severe threat could impact parts of the
    Texas Hill Country and east Texas later in the evening, before the
    threat becomes more isolated.

    ..Broyles/Squitieri.. 05/19/2026

    $$

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  • From COD Weather Processor@1:2320/107 to wx-storm@lists.illinois.edu on Tuesday, May 19, 2026 13:00:30
    ACUS01 KWNS 191300
    SWODY1
    SPC AC 191258

    Day 1 Convective Outlook
    NWS Storm Prediction Center Norman OK
    0758 AM CDT Tue May 19 2026

    Valid 191300Z - 201200Z

    ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FROM THE SOUTHERN
    PLAINS INTO THE LOWER MISSISSIPPI VALLEY/MID-SOUTH...OHIO
    VALLEY...AND LOWER GREAT LAKES...

    ...SUMMARY...
    Scattered severe thunderstorms will be possible today from the
    southern Plains into the lower Mississippi Valley/Mid-South, Ohio
    Valley, and lower Great Lakes. Damaging winds and hail will be the
    primary threats. A greater threat for large to very large hail
    should exist across parts of west-central Texas.

    ...Southern Plains into the Lower Mississippi Valley...
    Numerous thunderstorms are ongoing this morning across
    central/eastern OK into northwest AR and southern MO. Most of this
    activity is occurring along and north of a southward-moving cold
    front, and should therefore pose a limited severe risk in the short
    term. Eventual regeneration along the cold front and/or
    strengthening of ongoing activity should occur later today across TX
    into the lower MS Valley/Mid-South. Mid-level flow is forecast to
    remain fairly modest, and deep-layer shear for most areas will tend
    to be marginal. Still, filtered daytime heating of a moist low-level
    airmass will support moderate to strong instability along/ahead of
    the front by early afternoon. Scattered severe/damaging winds should
    be the main threat with loosely organized clusters and bowing line
    segments. This wind threat may continue to the TX/LA Coast this evening/overnight. Some potential for supercells should also exist
    across parts of west-central TX and vicinity, where steeper
    mid-level lapse rates and greater instability is forecast to be in
    place. Large hail appears possible with any supercells that can be
    sustained, and isolated 2+ inch diameter hail may occur. With time
    this evening, this convection may also grow upscale into a bowing
    cluster and pose a greater severe wind risk.

    ...Ohio Valley into the Lower Great Lakes and Northeast...
    Modestly enhanced mid-level southwesterly flow will be present today
    over the OH Valley and lower Great Lakes regions, as a positively
    tilted mid/upper-level trough moves from the Upper Midwest into
    eastern Canada. Isolated to scattered thunderstorms should develop
    along/ahead of a surface cold front this afternoon as the
    pre-frontal airmass gradually destabilizes. Stronger instability
    should be present this afternoon across the OH Valley, but greater
    deep-layer shear may tend to remain mostly displaced farther north.
    Even so, some thunderstorm organization should occur, with
    multicells and bowing line segments possible. Scattered
    severe/damaging winds should be the main threat, although isolated
    hail could occur with the strongest cores. This convection should
    spread into the lower Great Lakes by mid to late evening, before
    eventually weakening across the Northeast late tonight. A separate
    area of convection may develop this afternoon across parts of New
    England, and also pose a threat for mainly occasional damaging
    winds.

    ..Gleason/Marsh.. 05/19/2026

    $$

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  • From COD Weather Processor@1:2320/107 to wx-storm@lists.illinois.edu on Tuesday, May 19, 2026 16:21:01
    ACUS01 KWNS 191620
    SWODY1
    SPC AC 191619

    Day 1 Convective Outlook
    NWS Storm Prediction Center Norman OK
    1119 AM CDT Tue May 19 2026

    Valid 191630Z - 201200Z

    ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS THIS AFTERNOON
    OVER PART OF THE OHIO VALLEY INTO NEW YORK...AND THROUGH TONIGHT
    OVER PARTS OF TEXAS....

    ...SUMMARY...
    Scattered severe thunderstorms will be possible today from the
    southern Plains into the lower Mississippi Valley/Mid-South, Ohio
    Valley, and lower Great Lakes. Damaging winds and hail will be the
    primary threats. A greater threat for large to very large hail
    should exist across parts of west-central Texas.

    ...OH Valley and Lower Great Lakes...
    Deep southwesterly flow is present today from southern IL into much
    of the OH Valley and NY. Visible satellite imagery shows mostly
    clear skies in the region, allowing strong destabilization and
    steepening low-level lapse rates. The result will be a rather large
    zone of favorable environment for strong/damaging wind gusts this
    afternoon with any organized convection. Given the continued trend
    in morning model guidance of scattered clusters of storms in this
    corridor, the SLGT risk area has been maintained.

    ...South-central TX...
    A warm/moist and unstable air mass will develop this afternoon
    across parts of west-central TX. Scattered thunderstorm development
    is expected along a cold front sagging into the region. with weak
    supercells structures possible. These storms will track
    southeastward through the late afternoon/evening with a large hail
    threat. Eventual upscale growth into bowing structures may extend
    the severe risk overnight into south-central TX.

    ...East TX/LA/AR...
    Widespread overnight convection continues to build southeastward
    across southeast OK and western AR. This activity will persist much
    of the day and spread across much of AR/East TX/northern LA, in a
    region of relatively weak vertical shear and poor lapse rates.
    Storms may occasionally pose a risk of gusty/damaging winds, but the
    overall threat appears marginal.

    ..Hart/Halbert.. 05/19/2026

    $$

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  • From COD Weather Processor@1:2320/107 to wx-storm@lists.illinois.edu on Tuesday, May 19, 2026 19:55:02
    ACUS01 KWNS 191954
    SWODY1
    SPC AC 191953

    Day 1 Convective Outlook
    NWS Storm Prediction Center Norman OK
    0253 PM CDT Tue May 19 2026

    Valid 192000Z - 201200Z

    ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FROM THE LOWER
    OHIO VALLEY INTO THE LOWER GREAT LAKES...AND PARTS OF CENTRAL/SOUTH
    TEXAS...

    ...SUMMARY...
    Scattered severe thunderstorms will be possible today from the
    southern Plains into the lower Mississippi Valley/Mid-South, Ohio
    Valley, and lower Great Lakes. Damaging winds and hail will be the
    primary threats. A greater threat for large to very large hail
    should exist across parts of west-central Texas.

    ...20Z Update...
    The primary change to the forecast was to increase wind
    probabilities in parts of South Texas. Convection within the Rolling
    Plains should continue to develop this afternoon along a slowly
    moving cold front. Given the moisture surge ahead of this activity,
    it seems plausible that cold pool development will be robust enough
    to support continued development southward into the overnight.
    Recent HRRR guidance and the ECMWF support this possibility.
    Elsewhere, only minor changes where made based on current
    observations.

    ..Wendt.. 05/19/2026

    .PREV DISCUSSION... /ISSUED 1119 AM CDT Tue May 19 2026/

    ...OH Valley and Lower Great Lakes...
    Deep southwesterly flow is present today from southern IL into much
    of the OH Valley and NY. Visible satellite imagery shows mostly
    clear skies in the region, allowing strong destabilization and
    steepening low-level lapse rates. The result will be a rather large
    zone of favorable environment for strong/damaging wind gusts this
    afternoon with any organized convection. Given the continued trend
    in morning model guidance of scattered clusters of storms in this
    corridor, the SLGT risk area has been maintained.

    ...South-central TX...
    A warm/moist and unstable air mass will develop this afternoon
    across parts of west-central TX. Scattered thunderstorm development
    is expected along a cold front sagging into the region. with weak
    supercells structures possible. These storms will track
    southeastward through the late afternoon/evening with a large hail
    threat. Eventual upscale growth into bowing structures may extend
    the severe risk overnight into south-central TX.

    ...East TX/LA/AR...
    Widespread overnight convection continues to build southeastward
    across southeast OK and western AR. This activity will persist much
    of the day and spread across much of AR/East TX/northern LA, in a
    region of relatively weak vertical shear and poor lapse rates.
    Storms may occasionally pose a risk of gusty/damaging winds, but the
    overall threat appears marginal.

    $$

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  • From COD Weather Processor@1:2320/107 to wx-storm@lists.illinois.edu on Wednesday, May 20, 2026 00:45:03
    ACUS01 KWNS 200045
    SWODY1
    SPC AC 200043

    Day 1 Convective Outlook
    NWS Storm Prediction Center Norman OK
    0743 PM CDT Tue May 19 2026

    Valid 200100Z - 201200Z

    ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF
    THE SOUTHERN PLAINS AND FROM THE OHIO VALLEY INTO THE LOWER GREAT
    LAKES...

    ...SUMMARY...
    Isolated to scattered severe thunderstorms will be possible this
    evening from the southern Plains northeastward into mid Mississippi
    Valley and Lower Great Lakes. A greater threat for large hail will
    exist across parts of west-central Texas.

    ...Southern Plains...
    Southwest flow aloft is evident on water vapor imagery over the
    southern Plains. At the surface, an east-to-west oriented cold front
    is located across west and central Texas. Several strong
    thunderstorms are ongoing along the front. To the south of the
    front, surface dewpoints near 70 F are contributing to strong
    instability over the southern third of Texas, with the RAP showing
    MLCAPE in the 3000 to 4500 J/kg range. In addition, the RAP has
    steep mid-level lapse rates and moderate deep-layer shear analyzed
    across much of central and south Texas. This will be favorable for
    organized storms this evening capable of hail and severe wind gusts.
    Large hail will be most likely with any supercell that can develop.
    The severe threat is expected to move southward into south-central
    Texas by late evening. MCS development appears to be underway. As
    the convective coverage continues to increase, a transition to
    severe wind gusts as the primary threat is expected...see MCD 795.

    ...Mid Mississippi and Ohio Valleys/Lower Great Lakes...
    At mid-levels, a shortwave trough is evident on water vapor imagery
    over the Ohio Valley. A cold front is located from southern Indiana northeastward across central Ohio into the lower Great Lakes. A line
    of strong thunderstorms is ongoing near the front. Ahead of the
    front, surface dewpoints are in the 60s F which is enough for
    sufficient instability to support severe storm development. The RAP
    suggests that 0-3 km level lapse rates are still in the 7 to 7.5
    C/km ahead of the front from Ohio into northwest Pennsylvania. This
    could support isolated damaging wind gusts with the stronger cells
    embedded in the line...see MCD 797.

    ..Broyles.. 05/20/2026

    $$

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  • From COD Weather Processor@1:2320/107 to wx-storm@lists.illinois.edu on Wednesday, May 20, 2026 05:07:08
    ACUS01 KWNS 200507
    SWODY1
    SPC AC 200505

    Day 1 Convective Outlook
    NWS Storm Prediction Center Norman OK
    1205 AM CDT Wed May 20 2026

    Valid 201200Z - 211200Z

    ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF
    WEST TEXAS...

    ...SUMMARY...
    Scattered severe storms with large hail and isolated severe gusts
    are expected today across parts of west Texas. A few storms with
    isolated severe gusts and hail will also be possible from the
    central Appalachians into the Mid-Atlantic and far southern New
    England.

    ...Southern High Plains...
    Southwesterly mid-level flow will remain in place today over the
    south-central U.S. At the surface, a quasi-stationary front will be
    positioned from west Texas eastward into the Texas Hill Country.
    South of the front, surface dewpoints in the 70s F will result in an
    axis of moderate instability. The strongest instability is forecast
    to develop from the lower Rio Grande River Valley
    north-northwestward into far west Texas and eastern new Mexico. As
    instability increases during the day and low-level convergence
    becomes focused along the front, scattered thunderstorms are
    expected to develop across far west Texas. These storms will move
    eastward into west-central Texas by early to mid evening. Additional
    storms may develop further north-northwest into eastern New Mexico.

    RAP forecast soundings along the instability axis in the late
    afternoon from Fort Stockton northward to Midland have MLCAPE near
    2000 J/kg. 0-6 km is forecast to be around 50 knots with 700-500 mb
    lapse rate from 7 to 8 C/km. This environment will be favorable for
    supercells with large hail. The more dominant storms will have
    potential for hailstones greater than 2 inches in diameter. Isolated
    severe wind gusts will also be possible. A more isolated severe
    threat may also develop further north-northwest across the southern
    High Plains along the instability axis.

    ...Central Appalachians/Mid-Atlantic/Far Southern New England... West-southwesterly mid-level flow will be in place today across much
    of the eastern U.S. At the surface, a cold front will advance
    southward across the central Appalachians and Mid-Atlantic. To the
    south of the front, surface dewpoints in the upper 60s F will enable
    an axis of moderate instability to develop by afternoon. MLCAPE is
    forecast to peak in the 1000 to 2000 J/kg range in most areas ahead
    of the front. Increasing low-level convergence near the front will
    lead to scattered thunderstorm development during the afternoon.
    These storms will move eastward across the central Appalachians,
    Mid-Atlantic and far southern New England. RAP forecast soundings at
    21Z along and near the instability axis have 0-6 km shear up to 25
    knots with steep low-level lapse rates. This should support a severe
    threat with multicell storms. Isolated severe wind gusts and hail
    will be possible. The severe threat may persist into the early
    evening.

    ..Broyles/Squitieri.. 05/20/2026

    $$

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  • From COD Weather Processor@1:2320/107 to wx-storm@lists.illinois.edu on Wednesday, May 20, 2026 12:32:44
    ACUS01 KWNS 201232
    SWODY1
    SPC AC 201230

    Day 1 Convective Outlook
    NWS Storm Prediction Center Norman OK
    0730 AM CDT Wed May 20 2026

    Valid 201300Z - 211200Z

    ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF
    THE CENTRAL APPALACHIANS INTO THE MID-ATLANTIC AND SOUTHERN NEW
    ENGLAND...AND PARTS OF WEST/SOUTH-CENTRAL TEXAS...

    ...SUMMARY...
    Scattered severe/damaging winds and isolated hail will be possible
    with thunderstorms from the central Appalachians into the
    Mid-Atlantic and southern New England this afternoon and evening.
    Severe thunderstorms with large hail and isolated severe gusts may
    also occur today across parts of west/south-central Texas.

    ...Ohio Valley into the Mid-Atlantic and Southern New England...
    On the southern fringe of upper troughing over eastern Canada and
    the Great Lakes, a weak/convectively augmented mid-level shortwave
    trough will progress northeastward across the OH Valley and central Appalachians through the day, eventually reaching the Mid-Atlantic
    tonight. Robust daytime heating of a modestly moist low-level
    airmass (surface dewpoints generally in the low to mid 60s) ahead of
    a surface cold front will aid in the development of moderate
    instability by early afternoon. Ongoing convection across OH/KY this
    morning may eventually strengthen as it encounters this
    destabilizing airmass, and additional thunderstorms are expected to
    develop along/near the cold front by mid afternoon from the central Appalachians into portions of the Mid-Atlantic and southern New
    England.

    Stronger flow aloft will tend to lag/remain north of the cold front,
    but modest enhancement to the west-southwesterly mid-level flow
    along/near the front should support around 20-30 kt of deep-layer
    shear. This will be sufficient for some updraft organization with
    mainly multicells expected, although marginal supercell structures
    may occur. Low-level lapse rates are expected to become quite steep
    through the day, evidenced by a general lack of clouds on recent
    visible satellite imagery from central/eastern WV into the
    Mid-Atlantic. This will likely aid efficient downward momentum
    transfer in convective downdrafts, with scattered severe/damaging
    winds possible as multiple clusters spread east-northeastward
    through the afternoon/evening. Isolated hail may also occur with the
    stronger cores. A Slight Risk for severe/damaging winds has been
    introduced from parts of WV to southern New England given increased
    confidence in multiple clusters traversing a narrow zone along/ahead
    of the front.

    ...Eastern New Mexico into West/South-Central Texas...
    A squall line has generally moved offshore the lower/middle TX Coast
    this morning. In its wake, a post-frontal low-level upslope flow
    regime will persist today across west TX into eastern NM. Embedded
    within large-scale upper troughing over the Great Basin/Southwest, a low-amplitude shortwave trough over northern Mexico this morning
    will move northeastward across the southern High Plains by this
    afternoon. A relatively early start to convective development
    appears probable across the higher terrain of far west TX, possibly
    as early as 17-19Z. With a combination of moderate instability and
    40-50 kt of deep-layer shear forecast, supercells with mainly a
    large hail threat should be the primary mode initially. Additional
    robust thunderstorms may form later in the afternoon/early evening
    across a broader portion of the southern High Plains, and also pose
    a threat for large hail and isolated severe winds. Some potential
    for clustering this evening remains apparent into south-central TX,
    and supercells from north-central Mexico could also move into this
    region this evening/overnight.

    ..Gleason/Marsh.. 05/20/2026

    $$

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  • From COD Weather Processor@1:2320/107 to wx-storm@lists.illinois.edu on Wednesday, May 20, 2026 16:03:00
    ACUS01 KWNS 201602
    SWODY1
    SPC AC 201601

    Day 1 Convective Outlook
    NWS Storm Prediction Center Norman OK
    1101 AM CDT Wed May 20 2026

    Valid 201630Z - 211200Z

    ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FROM WEST VIRGINIA
    INTO THE MID-ATLANTIC STATES AND SOUTHERN NEW ENGLAND...AND OVER
    PORTIONS OF SOUTHWEST TEXAS....

    ...SUMMARY...
    Scattered severe/damaging winds and isolated hail will be possible
    with thunderstorms from the central Appalachians into the
    Mid-Atlantic and southern New England this afternoon and evening.
    Severe thunderstorms with large hail and isolated severe gusts may
    also occur today across parts of west/south-central Texas.

    ...WV to Southern New England...
    A broad upper ridge is present today over the southeastern U.S.,
    with the southern fringe of stronger westerlies extending from the
    OH Valley into the Mid-Atlantic region. Visible satellite imagery
    shows a zone of relatively clear skies from KY/WV into southeast
    PA/NJ and southern New England. Strong heating in this corridor
    will lead to moderate CAPE by mid-afternoon. Scattered thunderstorm development is expected, with steep low-level lapse rates and
    sufficient westerly flow above the boundary-layer supporting a risk
    of damaging wind gusts and some hail in the strongest
    cores/clusters.

    ...Southwest TX...
    Water vapor imagery shows a southern stream shortwave trough moving
    into northwest Mexico, with large scale ascent approaching west TX. Considerable cloud cover will persist in this region today, limiting heating/destabilization. Easterly low-level upslope flow will aid
    in the development of afternoon thunderstorms over the Davis
    mountains, with storms spreading slowly eastward through the
    evening. A few severe storms are possible, capable of large hail
    and gusty/damaging winds.

    ..Hart/Dean.. 05/20/2026

    $$

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  • From COD Weather Processor@1:2320/107 to wx-storm@lists.illinois.edu on Wednesday, May 20, 2026 19:58:02
    ACUS01 KWNS 201957
    SWODY1
    SPC AC 201956

    Day 1 Convective Outlook
    NWS Storm Prediction Center Norman OK
    0256 PM CDT Wed May 20 2026

    Valid 202000Z - 211200Z

    ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FROM EASTERN
    KENTUCKY INTO PARTS OF THE MID-ATLANTIC AND SOUTHERN NEW
    ENGLAND...AND PARTS OF SOUTHWEST TEXAS...

    ...SUMMARY...
    Scattered severe/damaging winds and isolated hail will be possible
    with thunderstorms from the central Appalachians into the
    Mid-Atlantic and southern New England this afternoon and evening.
    Severe thunderstorms with large hail and isolated severe gusts may
    also occur today across parts of west/south-central Texas.

    ...20Z Update...
    The forecast remains largely on track. Only minor adjustment to the
    wind probabilities were made based on current observations and
    recent guidance.

    ..Wendt.. 05/20/2026

    .PREV DISCUSSION... /ISSUED 1101 AM CDT Wed May 20 2026/

    ...WV to Southern New England...
    A broad upper ridge is present today over the southeastern U.S.,
    with the southern fringe of stronger westerlies extending from the
    OH Valley into the Mid-Atlantic region. Visible satellite imagery
    shows a zone of relatively clear skies from KY/WV into southeast
    PA/NJ and southern New England. Strong heating in this corridor
    will lead to moderate CAPE by mid-afternoon. Scattered thunderstorm development is expected, with steep low-level lapse rates and
    sufficient westerly flow above the boundary-layer supporting a risk
    of damaging wind gusts and some hail in the strongest
    cores/clusters.

    ...Southwest TX...
    Water vapor imagery shows a southern stream shortwave trough moving
    into northwest Mexico, with large scale ascent approaching west TX. Considerable cloud cover will persist in this region today, limiting heating/destabilization. Easterly low-level upslope flow will aid
    in the development of afternoon thunderstorms over the Davis
    mountains, with storms spreading slowly eastward through the
    evening. A few severe storms are possible, capable of large hail
    and gusty/damaging winds.

    $$

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  • From COD Weather Processor@1:2320/107 to wx-storm@lists.illinois.edu on Thursday, May 21, 2026 00:45:35
    ACUS01 KWNS 210045
    SWODY1
    SPC AC 210043

    Day 1 Convective Outlook
    NWS Storm Prediction Center Norman OK
    0743 PM CDT Wed May 20 2026

    Valid 210100Z - 211200Z

    ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS FROM PARTS OF
    WEST AND SOUTHWEST TEXAS INTO SOUTH-CENTRAL TEXAS...

    ...SUMMARY...
    Isolated severe storms with hail and strong wind gusts will be
    possible across parts of west and southwest Texas this evening.
    Isolated severe gusts may also occur in south-central Texas in the
    late evening and early overnight period.

    ...West, Southwest and South-central Texas...
    A mid-level shortwave trough is evident over far west Texas.
    Large-scale ascent associated with the trough is providing support
    for scattered thunderstorm development early this evening. The
    storms are located near a quasi-stationary front extending eastward
    from near Fort Stockton into the Texas Hill Country. To the south of
    the front, surface dewpoints are mostly in the mid to upper 60s F.
    The RAP suggests that MLCAPE ranges from around 1000 J/kg near the
    front to about 2500 J/kg in the lower Rio Grande Valley southeast of
    Del Rio. As the shortwave trough moves into west-central Texas over
    the next few hours, new convection is expected to initiate from the
    far western Texas Hill Country into southwest Texas. In addition to
    moderate instability, the Del Rio 00Z sounding has 0-6 km shear
    around 30 knots with 700-500 mb lapse rates approaching 7.5 C/km.
    This environment will support isolated severe storm development.
    Rotating cells should be capable of isolated large hail. A few
    severe wind gusts could also occur. The potential for isolated
    severe gusts may continue after midnight across parts of
    south-central Texas, as a convective cluster crosses the Rio Grande
    River.

    ..Broyles.. 05/21/2026

    $$

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  • From COD Weather Processor@1:2320/107 to wx-storm@lists.illinois.edu on Thursday, May 21, 2026 05:53:35
    ACUS01 KWNS 210553
    SWODY1
    SPC AC 210552

    Day 1 Convective Outlook
    NWS Storm Prediction Center Norman OK
    1252 AM CDT Thu May 21 2026

    Valid 211200Z - 221200Z

    ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF
    EASTERN COLORADO...

    ...SUMMARY...
    Thunderstorms with a threat for large hail, isolated severe gusts
    and possibly a tornado are expected in parts of eastern Colorado
    from mid afternoon to early evening. Isolated large hail will also
    be possible in parts of the southern High Plains this afternoon.

    ...Central and Southern High Plains...
    An upper-level trough will move eastward into the central Rockies
    today. Ahead of the trough, a lee surface low will form over eastern
    Colorado. As surface temperatures warm, convection will initiate in
    the higher terrain near Denver and Colorado Springs. From this
    convection, storms will develop and move eastward into the central
    High Plains during the afternoon. In eastern Colorado, a
    north-to-south axis of instability will be in place by afternoon,
    where model forecasts have MLCAPE peaking around 1500 J/kg. In
    addition, late afternoon RAP forecast soundings in eastern Colorado
    have 0-6 km shear in the 45 to 55 knot range with 700-500 mb lapse
    rates near 8 C/km. This will be favorable for supercells with large
    hail and isolated severe gusts. If a supercell can become locally
    dominant, then a tornado will also be possible. The severe threat
    will likely persist into early evening.

    Further south into the southern High Plains, an axis of instability
    will be in place by afternoon. The strongest instability is forecast
    on the Caprock of west Texas, where 0-6 km shear is forecast to be
    around 30 knots. This, along with 700-500 mb lapse rates near 7
    C/km, may be enough for an isolated large hail threat.

    ..Broyles/Squitieri.. 05/21/2026

    $$

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  • From COD Weather Processor@1:2320/107 to wx-storm@lists.illinois.edu on Thursday, May 21, 2026 12:51:43
    ACUS01 KWNS 211251
    SWODY1
    SPC AC 211250

    Day 1 Convective Outlook
    NWS Storm Prediction Center Norman OK
    0750 AM CDT Thu May 21 2026

    Valid 211300Z - 221200Z

    ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF
    THE CENTRAL/SOUTHERN HIGH PLAINS...

    ...SUMMARY...
    Thunderstorms capable of producing large hail and isolated severe
    gusts should occur across parts of the central/southern High Plains
    this afternoon and evening. A tornado or two may also occur.

    ...Central/Southern High Plains into South Texas...
    Within large-scale upper troughing over the northern Rockies/Great
    Basin, an embedded mid-level shortwave trough and associated jet
    will translate southeastward across the central Rockies and adjacent
    High Plains this afternoon and evening. Forcing for ascent preceding
    this feature will encourage initial isolated to scattered
    thunderstorm development across the higher terrain of central CO by
    mid afternoon. A weak southern-stream perturbation should also
    foster scattered convection farther south across the southern High
    Plains as well.

    The airmass across the central/southern High Plains should gradually destabilize today, as modest moisture in a persistent low-level
    upslope flow regime continues streaming northwestward across these
    regions beneath steepened mid-level lapse rates. Weak to moderate
    instability is forecast to be in place by mid afternoon, with
    sufficient deep-layer shear for a mix of multicells and supercells.
    Initial development should pose a threat for large hail, before
    eventual clustering this evening potentially results in a greater
    threat for severe winds. The primary change with this update was to
    expand the Marginal Risk across parts of west into south TX, where
    any convection which develops eastward may pose an isolated
    hail/wind threat this afternoon through tonight.

    ...Southern Virginia into North Carolina...
    Daytime heating south of a cold front should help steepen low-level
    lapse rates across parts of southern VA into NC by this afternoon.
    While both mid-level flow and lapse rates are expected to remain
    fairly modest across this area, an isolated threat for damaging
    winds may exist with loosely organized clusters that can develop
    along the higher terrain and/or sagging cold front this afternoon.

    ...Coastal Texas into the Lower Mississippi Valley...
    Another expansive MCS has moved offshore from the lower TX Coast
    this morning. Generally weak offshore surface flow continues across
    the middle/upper TX Coast into southern LA. Eventually, a more
    southerly component to the low-level winds may encourage greater
    low-level moisture to advance inland later today across parts of the
    lower MS Valley. While a couple of stronger thunderstorms with gusty
    winds appear possible, modest mid-level flow and poor lapse rates
    aloft should tend to limit the overall severe threat.

    ..Gleason/Marsh.. 05/21/2026

    $$

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  • From COD Weather Processor@1:2320/107 to wx-storm@lists.illinois.edu on Thursday, May 21, 2026 16:17:44
    ACUS01 KWNS 211617
    SWODY1
    SPC AC 211615

    Day 1 Convective Outlook
    NWS Storm Prediction Center Norman OK
    1115 AM CDT Thu May 21 2026

    Valid 211630Z - 221200Z

    ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS THIS AFTERNOON AND
    EVENING OVER PARTS OF EASTERN COLORADO....

    ...SUMMARY...
    Thunderstorms capable of producing large hail and isolated severe
    gusts should occur across parts of the central/southern High Plains
    this afternoon and evening. A tornado or two may also occur.

    ...High Plains...
    Water vapor imagery shows an upper trough moving across western
    WY/CO. This feature will spread weak/broad large scale forcing for
    ascent across much of the High Plains from SD to NM this afternoon.
    At the surface, southerly low level winds have resulted in an axis
    of 40s/50s dewpoints along this corridor. Low clouds are slowly
    eroding, which should result in moderate CAPE values and aid in the
    development of widely scattered afternoon thunderstorms.

    Isolated storms will likely form first over parts of eastern NM.
    This activity will build slowly eastward toward west TX with a risk
    of large hail.

    By mid/late afternoon, storms will likely develop off the Raton and
    Palmer ridges, spreading eastward toward western KS this evening.
    Shear profiles in this area will be stronger than farther south,
    supporting longer-lived storms capable of large hail, damaging
    winds, and perhaps a tornado or two.

    An isolated cell or two may also produce occasional severe hail over
    parts of eastern WY and into the Black Hills region later this
    afternoon.

    ...Carolinas/VA...
    Clear skies are leading to strong heating over parts of southern VA
    into part of NC/SC. Scattered afternoon thunderstorms are expected
    to form in this zone, with steep low-level lapse rates and
    sufficient CAPE supporting a risk of gusty/damaging winds in the
    strongest cells.

    ..Hart/Lyons.. 05/21/2026

    $$

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  • From COD Weather Processor@1:2320/107 to wx-storm@lists.illinois.edu on Thursday, May 21, 2026 19:57:41
    ACUS01 KWNS 211957
    SWODY1
    SPC AC 211956

    Day 1 Convective Outlook
    NWS Storm Prediction Center Norman OK
    0256 PM CDT Thu May 21 2026

    Valid 212000Z - 221200Z

    ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ...

    ...SUMMARY...
    Thunderstorms capable of producing large hail and isolated severe
    gusts should occur across parts of the central/southern High Plains
    this afternoon and evening. A tornado or two may also occur.

    ...Discussion...
    The ongoing forecast remains on track. Moved Slight back farther
    west to where ongoing storms are in southeast Colorado and northeast
    New Mexico. MRMS MESH currently shows around 1 inch hail with these
    cells with some strengthening anticipated as they move into a more
    unstable airmass to the east. For additional information, see MCD
    812.

    A few stronger cells have developed across West Texas where greater
    instability has developed. Isolated large hail and severe wind gusts
    are possible, but the overall threat is expected to remain
    sub-severe. See MCD 813 for additional information about the storms
    in this area.

    Strong to isolated severe storms have developed across North
    Carolina and southern Virginia and are expected to persist through
    the afternoon and early evening. See MCD 814 for additional
    discussion.

    ..Bentley.. 05/21/2026

    .PREV DISCUSSION... /ISSUED 1115 AM CDT Thu May 21 2026/

    ...High Plains...
    Water vapor imagery shows an upper trough moving across western
    WY/CO. This feature will spread weak/broad large scale forcing for
    ascent across much of the High Plains from SD to NM this afternoon.
    At the surface, southerly low level winds have resulted in an axis
    of 40s/50s dewpoints along this corridor. Low clouds are slowly
    eroding, which should result in moderate CAPE values and aid in the
    development of widely scattered afternoon thunderstorms.

    Isolated storms will likely form first over parts of eastern NM.
    This activity will build slowly eastward toward west TX with a risk
    of large hail.

    By mid/late afternoon, storms will likely develop off the Raton and
    Palmer ridges, spreading eastward toward western KS this evening.
    Shear profiles in this area will be stronger than farther south,
    supporting longer-lived storms capable of large hail, damaging
    winds, and perhaps a tornado or two.

    An isolated cell or two may also produce occasional severe hail over
    parts of eastern WY and into the Black Hills region later this
    afternoon.

    ...Carolinas/VA...
    Clear skies are leading to strong heating over parts of southern VA
    into part of NC/SC. Scattered afternoon thunderstorms are expected
    to form in this zone, with steep low-level lapse rates and
    sufficient CAPE supporting a risk of gusty/damaging winds in the
    strongest cells.

    $$

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  • From COD Weather Processor@1:2320/107 to wx-storm@lists.illinois.edu on Friday, May 22, 2026 00:42:52
    ACUS01 KWNS 220042
    SWODY1
    SPC AC 220040

    Day 1 Convective Outlook
    NWS Storm Prediction Center Norman OK
    0740 PM CDT Thu May 21 2026

    Valid 220100Z - 221200Z

    ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF
    THE CENTRAL HIGH PLAINS...

    ...SUMMARY...
    Thunderstorms capable of producing large hail and isolated severe
    wind gusts will continue across parts of the central and southern
    High Plains evening. A tornado may also occur in the central High
    Plains.

    ...Central and Southern High Plains...
    The latest water vapor imagery shows a mid-level shortwave trough
    extending southward from the northern High Plains into the central
    Rockies, with another smaller-scale trough located in the central
    High Plains. At the surface, a low is located over southeast
    Colorado with a trough extending southward into eastern New Mexico.
    Scattered severe thunderstorms are ongoing in northeast Colorado. A
    severe line segment is also ongoing from far southwest Kansas south-southwestward into the far northwestern Texas Panhandle. These
    storms are located along and near an axis of moderate instability,
    where the RAP has MLCAPE in the 1000 to 2000 J/kg range. Moderate
    deep-layer shear is analyzed along the axis of instability. The
    Goodland WSR-88D VWP has 0-6km shear near 50 knots, which will
    support a threat for supercells this evening. The stronger storms
    will be capable of producing large hail and isolated severe wind
    gusts...see MCDs 821 and 819.

    Further south into the southern High Plains, two areas of scattered
    strong thunderstorms are ongoing. The first is west of Lubbock from
    far eastern New Mexico into west Texas. The second is in the western
    Texas Hill Country. The storms are located along an axis of moderate instability. Along this axis, deep-layer shear appears sufficient
    for an isolated severe threat early this evening.

    ..Broyles.. 05/22/2026

    $$

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  • From COD Weather Processor@1:2320/107 to wx-storm@lists.illinois.edu on Friday, May 22, 2026 06:01:21
    ACUS01 KWNS 220601
    SWODY1
    SPC AC 220559

    Day 1 Convective Outlook
    NWS Storm Prediction Center Norman OK
    1259 AM CDT Fri May 22 2026

    Valid 221200Z - 231200Z

    ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF
    THE SOUTHERN HIGH PLAINS...

    ...SUMMARY...
    Thunderstorms with large hail and severe wind gusts will be possible
    from late this afternoon into the evening in parts of the southern
    High Plains. Isolated severe gusts and hail may occur in parts of
    the mid Missouri Valley. A few severe gusts and a marginal tornado
    threat will also be possible from the central Gulf Coast States into
    the Tennessee and southern Ohio Valleys.

    ...Southern High Plains...
    A mid-level shortwave trough will move eastward into the southern
    High Plains today. Ahead of the trough, a moist and unstable airmass
    will be located across most of Texas and Oklahoma. Thunderstorms are
    expected to develop late this afternoon on the moisture gradient
    from the western Texas Panhandle southward into west Texas. These
    storms will move eastward across the southern High Plains during the
    late afternoon and evening.

    The strongest instability is forecast to develop this afternoon over
    the low Rolling Plains of northwest Texas, where model forecasts
    have MLCAPE peaking in the 2000 to 3000 J/kg range. Late afternoon
    forecast soundings in northwest Texas have 0-6 km shear around 30
    knots with 700-500 mb lapse rates near 8 C/km. This environment will
    support the development of supercells with large hail and severe
    wind gusts. Hailstones greater than 2 inches in diameter will be
    possible with supercells that become dominant. The greatest severe
    threat is expected to be in the evening as a broken line of storms
    moves into the stronger instability from the eastern Texas Panhandle
    southward into northwest Texas.

    ...Mid Missouri Valley...
    An upper-level trough and an associated mid-level jet streak will
    move northeastward today across the north-central U.S. At the
    surface, an axis of low-level moisture will be in place from eastern
    Kansas northward into eastern Nebraska. Ahead of the trough,
    scattered thunderstorms will develop in the afternoon along and near
    the moist axis. Surface dewpoints in the lower to mid 60s F will
    contribute to weak instability with MLCAPE likely peaking in the 500
    to 1000 J/kg range across eastern Nebraska. RAP forecast soundings
    near Omaha suggest that 0-6 km shear will reach 35 knots as the
    trough approaches this afternoon, which would support the
    development of low-topped supercells capable of isolated severe wind
    gusts and hail. The severe threat is expected to persist into the
    early evening.

    ...Central Gulf Coast States/Ohio and Tennessee Valleys...
    A negatively-tilted mid-level shortwave trough will move
    northeastward today across the east-central U.S. Ahead of the
    trough, low-level moisture advection will take place. By early
    afternoon, surface dewpoints will be from the mid 60s to lower 70s F
    from the central Gulf Coast states northward into the southern Ohio
    Valley. Moderate instability is expected by afternoon across much of
    the region with MLCAPE peaking between 1500 and 2500 J/kg. Locally
    stronger instability is expected across central Mississippi,
    east-central Kentucky, eastern Tennessee and northeast Georgia. As
    surface temperatures warm during the day, scattered thunderstorms
    will develop and move northeastward across the moist airmass.
    Steepening low-level lapse rates will support a potential for
    isolated severe wind gusts. In addition, hodographs across this
    unstable airmass are forecast to be somewhat curved, which should
    also support a marginal tornado threat.

    ..Broyles/Chalmers.. 05/22/2026

    $$

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  • From COD Weather Processor@1:2320/107 to wx-storm@lists.illinois.edu on Friday, May 22, 2026 12:50:47
    ACUS01 KWNS 221250
    SWODY1
    SPC AC 221249

    Day 1 Convective Outlook
    NWS Storm Prediction Center Norman OK
    0749 AM CDT Fri May 22 2026

    Valid 221300Z - 231200Z

    ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FOR THE TEXAS
    PANHANDLE AND NORTHWEST TEXAS INTO SOUTHWEST OKLAHOMA...

    ...SUMMARY...
    Thunderstorms with large to very large hail and severe gusts are
    possible late this afternoon into the evening in parts of the
    southern High Plains.

    ...Southern High Plains...
    Modest cyclonic mid-level flow will extend from the Interior West
    through the base of the trough over the south-central U.S.
    Water-vapor imagery shows a weak disturbance migrating east across
    the Permian Basin this morning. A seasonably moist airmass
    maintained via southeasterly low-level flow will heat and become
    moderately to strongly unstable by mid afternoon.

    Model forecast soundings show relatively cool 500-mb temperatures
    (near -14 deg C) with steep low- to mid-level lapse rates later this
    afternoon. Strong heating will locally erode appreciable remaining
    convective inhibition and widely scattered thunderstorms will likely
    develop by late afternoon. Although westerly flow will likely
    remain modest (20 kt from 600 to 200 mb), strongly veering flow will
    result in 25-30 kt effective shear, supporting supercells initially.
    Large to very large hail will be possible with the more intense
    updrafts. Increasing storm coverage during the evening will tend to
    promote some upscale growth into a linear cluster with severe gusts
    becoming more prevalent. The risk for severe gusts (60-80 mph) may
    focus during the 00-03 UTC period before a gradual waning in
    coverage/intensity by late evening.

    ...Central Gulf Coast States/Ohio and Tennessee Valleys...
    Water-vapor imagery shows a disturbance moving northeastward across
    the ArkLaMiss this morning and moving towards western portions of
    TN/KY and the lower OH Valley. Surface analysis indicates a moist
    airmass featuring dewpoints ranging from the upper 60s over TN to
    the lower 70s over the central Gulf Coast. Despite widespread cloud
    cover, some thinning of the cloud shield is expected as temperatures
    slowly warm through the early afternoon. Models generally show weak
    buoyancy (500-1000 J/kg MLCAPE) and skinny CAPE profiles and
    tempered lapse rates (reference the Nashville and Birmingham 12 UTC
    raobs). However, models show some enhancement/strengthening of
    925-500 mb flow moving northeastward across MS/AL into TN through
    the mid-late afternoon. As a result, some enlargement of hodographs
    will likely occur during the diurnal heating cycle and a few weak
    supercell structures will probably develop. Yet, the ongoing
    thunderstorm band over eastern MS may be ill timed as it moves
    northeastward across western/northern AL through midday.
    Nonetheless, an isolated risk for a tornado seems possible over much
    of this general region. A risk for isolated damaging gusts may also
    accompany some of the stronger thunderstorms before this activity
    wanes by the early evening.

    ...Mid Missouri Valley...
    An upper-level trough and an associated mid-level jet streak will
    move northeastward today across the north-central U.S. At the
    surface, an axis of low-level moisture will be in place from eastern
    Kansas northward into eastern Nebraska. Ahead of the trough,
    scattered thunderstorms will develop in the afternoon along and near
    the moist axis. Surface dewpoints in the lower to mid 60s F will
    contribute to weak instability with MLCAPE likely peaking in the 500
    to 1000 J/kg range across eastern Nebraska. RAP forecast soundings
    near Omaha suggest that 0-6 km shear will reach 35 knots as the
    trough approaches this afternoon, which would support the
    development of low-topped supercells capable of isolated severe wind
    gusts and hail. The severe threat is expected to persist into the
    early evening.

    ..Smith/Weinman.. 05/22/2026

    $$

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  • From COD Weather Processor@1:2320/107 to wx-storm@lists.illinois.edu on Friday, May 22, 2026 16:06:49
    ACUS01 KWNS 221606
    SWODY1
    SPC AC 221604

    Day 1 Convective Outlook
    NWS Storm Prediction Center Norman OK
    1104 AM CDT Fri May 22 2026

    Valid 221630Z - 231200Z

    ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS THIS AFTERNOON AND
    EVENING OVER PARTS OF WEST TX AND WESTERN OKLAHOMA...

    ...SUMMARY...
    Thunderstorms with large hail and severe gusts are possible late
    this afternoon into the evening in parts of the southern High
    Plains. A few brief tornadoes are also possible across the Mid
    South.

    ...TX/OK...
    A weak upper trough is moving across CO today, with the tail end of
    large scale forcing spreading across the TX Panhandle. At the
    surface, southeasterly winds will maintain a moist air mass into the
    region, where a dryline will become the focus for afternoon
    thunderstorm development. Weak mid-level winds of 20-30 knots
    suggest that storms will be a mix of multicell and supercell
    structures capable of large hail and damaging winds. Merging
    outflows are expected as activity spreads eastward into western OK
    and eventually north TX tonight, with a continued risk of locally
    damaging winds.

    ...Northeast NE/KS/Northwest OK...
    A cold front is sagging southeastward into KS/NE, where a moist and
    moderately unstable air mass will be present this afternoon.
    Scattered thunderstorms are expected along/ahead of the front, with
    a low-end risk of hail in the stronger cells.

    ...TN/MS/AL/GA...
    A broad area of moderately strong southerly low-level winds are
    present today over parts of the Mid-South and TN Valley, along with
    a very moist air mass with dewpoints in the 70s. Forecast soundings
    show rather weak CAPE, but sufficient low-level shear for some
    concern for tornadoes today. There have been occasional
    mesocyclones in the thunderstorms in this region, and that will
    likely continue through the afternoon as the low-level jet shifts
    northward into northern AL/middle TN. Overall confidence in the
    tornado threat suggests the threat remains Marginal, but a tactical
    upgrade to portions of the area remains possible this afternoon.

    ..Hart/Lyons.. 05/22/2026

    $$

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  • From COD Weather Processor@1:2320/107 to wx-storm@lists.illinois.edu on Friday, May 22, 2026 19:36:18
    ACUS01 KWNS 221936
    SWODY1
    SPC AC 221934

    Day 1 Convective Outlook
    NWS Storm Prediction Center Norman OK
    0234 PM CDT Fri May 22 2026

    Valid 222000Z - 231200Z

    ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF
    NORTHWEST TEXAS AND WESTERN OKLAHOMA...

    ...SUMMARY...
    Thunderstorms with large hail and severe gusts are possible late
    this afternoon into the evening in parts of the southern High
    Plains. A few brief tornadoes are also possible across the Mid
    South.

    ...20z Update...

    Only minor adjustments have been made to the Marginal (level 1 of 5)
    risk across southwest Kansas based on the current location of the
    surface cold front. Scattered thunderstorms will increase across the
    southern High Plains late this afternoon into this evening, posing a
    risk for damaging wind gusts and isolated large hail.

    Across the TN Valley vicinity, sporadic rotating storms may persist
    another couple of hours and a brief tornado is possible. However,
    the 30-40 kt low-level jet will continue to shift northward with
    time and away from the axis of stronger instability. Otherwise,
    sporadic gusty winds are possible through evening. For more short
    term details, reference MCDs 825 and 826.

    ..Leitman.. 05/22/2026

    .PREV DISCUSSION... /ISSUED 1104 AM CDT Fri May 22 2026/

    ...TX/OK...
    A weak upper trough is moving across CO today, with the tail end of
    large scale forcing spreading across the TX Panhandle. At the
    surface, southeasterly winds will maintain a moist air mass into the
    region, where a dryline will become the focus for afternoon
    thunderstorm development. Weak mid-level winds of 20-30 knots
    suggest that storms will be a mix of multicell and supercell
    structures capable of large hail and damaging winds. Merging
    outflows are expected as activity spreads eastward into western OK
    and eventually north TX tonight, with a continued risk of locally
    damaging winds.

    ...Northeast NE/KS/Northwest OK...
    A cold front is sagging southeastward into KS/NE, where a moist and
    moderately unstable air mass will be present this afternoon.
    Scattered thunderstorms are expected along/ahead of the front, with
    a low-end risk of hail in the stronger cells.

    ...TN/MS/AL/GA...
    A broad area of moderately strong southerly low-level winds are
    present today over parts of the Mid-South and TN Valley, along with
    a very moist air mass with dewpoints in the 70s. Forecast soundings
    show rather weak CAPE, but sufficient low-level shear for some
    concern for tornadoes today. There have been occasional
    mesocyclones in the thunderstorms in this region, and that will
    likely continue through the afternoon as the low-level jet shifts
    northward into northern AL/middle TN. Overall confidence in the
    tornado threat suggests the threat remains Marginal, but a tactical
    upgrade to portions of the area remains possible this afternoon.

    $$

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  • From COD Weather Processor@1:2320/107 to wx-storm@lists.illinois.edu on Saturday, May 23, 2026 00:53:51
    ACUS01 KWNS 230053
    SWODY1
    SPC AC 230052

    Day 1 Convective Outlook
    NWS Storm Prediction Center Norman OK
    0752 PM CDT Fri May 22 2026

    Valid 230100Z - 231200Z

    ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF
    THE SOUTHERN HIGH PLAINS...

    ...SUMMARY...
    Thunderstorms with large hail, severe gusts and a few brief
    tornadoes are possible this evening in parts of the southern High
    Plains. Isolated severe gusts will also be possible in the
    Ark-La-Tex/lower Mississippi Valley

    ...Southern High Plains...
    On water vapor imagery, a mid-level shortwave trough is evident over
    the southern High Plains. At the surface, a dryline is located
    across west Texas. To the east of the dryline, surface dewpoints are
    in the 60s F and the RAP has MLCAPE in the 2000 to 3500 J/kg range.
    Scattered thunderstorms are ongoing along the western edge of
    moderate instability from near Amarillo south-southeastward into the
    low Rolling Plains. Ahead of the storms, forecast soundings in
    northwest Texas have 35 to 40 knots of deep-layer shear with 700-500
    mb lapse rates near 7.5 C/km. This will support a potential for
    isolated supercells with large hail. Hailstones greater than 2
    inches in diameter will be possible. In addition, the stronger
    storms could be associated with a brief tornado threat. Severe wind
    gusts will also be possible, and this threat could increase as the
    storms continue to become more linear later this evening...see MCD
    830.

    Further south across the remainder of west Texas, storms will be
    more widely spaced. Moderate instability and steep mid-level lapse
    rates will support a potential for isolated supercells with
    hail...see MCD 831.

    ...Ark-La-Tex/Lower Mississippi Valley...
    The latest RAP has an axis of moderate to strong instability
    analyzed from northeast Texas eastward across northern Louisiana,
    where MLCAPE is in the 2500 to 3500 J/kg range. Along this corridor,
    low-level lapse rates are steep. This thermodynamic environment will
    support multicells with an isolated potential for severe wind gusts
    early this evening.

    ..Broyles.. 05/23/2026

    $$

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  • From COD Weather Processor@1:2320/107 to wx-storm@lists.illinois.edu on Saturday, May 23, 2026 05:28:53
    ACUS01 KWNS 230528
    SWODY1
    SPC AC 230527

    Day 1 Convective Outlook
    NWS Storm Prediction Center Norman OK
    1227 AM CDT Sat May 23 2026

    Valid 231200Z - 241200Z

    ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF
    THE SOUTHERN PLAINS...WESTERN AND CENTRAL GULF COAST...FROM GEORGIA
    INTO SOUTH CAROLINA...AND ACROSS OHIO...

    ...SUMMARY...
    Thunderstorms with isolated severe wind gusts and hail will be
    possible this afternoon and evening across parts of the southern
    Plains. A few strong wind gusts and an isolated tornado threat will
    be possible from southeast Texas into southern Louisiana. A few
    strong gusts may also occur from Georgia into South Carolina. An
    isolated tornado threat is also expected in parts of Ohio.

    ...Southern High Plains...
    An upper-level trough will move eastward today across the Great
    Plains. At the surface, a broad moist sector will be in place across
    the southern Plains where dewpoints will be mostly in the 60s F. In
    response, an axis of moderate instability will develop by afternoon
    from the Texas Panhandle southward into west Texas. Scattered
    thunderstorms are expected to form during the mid to late afternoon
    near this axis of instability. RAP forecast soundings in the Texas
    Panhandle in the late afternoon have MLCAPE near 1500 J/kg and 0-6
    km shear in the 25 to 35 knot range, with 700-500 mb lapse rates
    around 8 C/km. This should support a marginal severe threat.
    Isolated large hail and a few strong wind gusts will be possible.

    ...South-central and Southeast Texas/Southern Louisiana...
    In the coastal areas of the western and central Gulf, very moist air
    will be in place. Surface dewpoints in the lower to mid 70s F will
    contribute to moderate instability by midday. Thunderstorms will
    form along sea breeze boundaries during the early to mid afternoon.
    A few severe wind gusts and a brief tornado will be possible.

    Further west into parts of south-central Texas, moderate to strong
    instability is forecast by afternoon with MLCAPE peaking in the 2500
    to 3500 J/kg range. This, combined with moderate deep-layer shear,
    may support isolated severe storm development this afternoon. The
    primary threats would be for hail and isolated severe wind gusts.

    ...Georgia/South Carolina...
    A mid-level shortwave trough will move across the Southeast today.
    At the surface, moist air will be in place from the Gulf Coast
    states into the Carolinas, where moderate instability will develop
    by midday. During the afternoon, scattered thunderstorms will form
    from Georgia into South Carolina. As instability increases during
    the day, low-level lapse rates will become steep. This should be
    sufficient for an isolated potential for severe wind gusts.

    ...Ohio...
    Southwesterly mid-level flow will be in place over the Ohio Valley
    and lower Great Lakes today. At the surface, an axis of low-level
    moisture will be located from eastern Kentucky into central and
    northern Ohio, where dewpoints will be in the mid to upper 60s F. As instability increases during the day, scattered thunderstorms are
    expected to develop and move northeastward across the instability
    corridor. RAP forecast soundings in central Ohio at 21Z have 0-6 km
    shear near 30 knots with 0-3 km storm-relative helicity around 150
    m2/s2. This could be enough for an isolated tornado threat.

    ..Broyles/Chalmers.. 05/23/2026

    $$

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  • From COD Weather Processor@1:2320/107 to wx-storm@lists.illinois.edu on Saturday, May 23, 2026 12:51:56
    ACUS01 KWNS 231251
    SWODY1
    SPC AC 231250

    Day 1 Convective Outlook
    NWS Storm Prediction Center Norman OK
    0750 AM CDT Sat May 23 2026

    Valid 231300Z - 241200Z

    ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF
    THE SOUTHERN PLAINS AND CENTRAL HIGH PLAINS...WESTERN AND CENTRAL
    GULF COAST...GEORGIA INTO SOUTH CAROLINA...AND ACROSS OHIO...

    ...SUMMARY...
    Isolated severe thunderstorms are possible today across the lower
    Mississippi Valley and into parts of Texas. Other isolated severe
    storms are possible in portions of the Southeast, Ohio, and the
    central High Plains.

    ...Southern High Plains...
    Weak mid-level flow and an ill-defined surface pattern aptly
    characterize the severe-potential setup for later today into the
    evening across this region. Residual low-level moisture and steep
    700-500 mb lapse rates (reference the 12 UTC Midland, TX raob; 8.7
    deg C/km) in combination with strong heating will result in moderate instability developing by mid-late afternoon. Scattered
    thunderstorms are forecast to develop from near the CO/OK-TX
    Panhandles border region southward into the Edwards Plateau.
    Isolated large hail and severe gusts will be the primary severe
    hazards with the stronger storms. Some clustering is expected
    during the evening before this activity diminishes by late evening.

    ...South-central and Southeast Texas/Southern Louisiana...
    In the coastal areas of the western and central Gulf, very moist air
    will be in place. Surface dewpoints in the lower to mid 70s F will
    contribute to moderate instability by midday. Thunderstorms will
    form along sea breeze boundaries during the early to mid afternoon.
    A few severe wind gusts and a brief tornado will be possible.
    Farther north over the Ark-La-Miss, some heating ahead of a
    north-south band of showers/thunderstorms associated with an MCV
    over OK, will contribute to a marginally supportive wind-damage
    risk. Have expanded low-wind probabilities to account for
    observational trends of a semi-organized band of storms continuing
    east into the Ark-La-Miss during peak heating.

    ...Georgia/South Carolina...
    A weak mid-level disturbance over MS/AL this morning will move east-northeastward today. Adequate heating of a moist boundary
    layer will yield 500-1000 J/kg MLCAPE by early afternoon and
    scattered showers/thunderstorms are forecast. Deep-layer shear will
    support some multicellular organization in the form of a few
    thunderstorm clusters. The stronger water-loaded downdrafts will
    potentially yield a localized wind-damage risk during the afternoon
    before this threat wanes by early evening.

    ...Central High Plains...
    Latest model guidance shows isolated thunderstorms developing late
    this afternoon within a belt of stronger cyclonic mid-level flow
    associated with a north-central U.S. larger-scale mid-level trough.
    The 30-40 kt 500-mb flow and steepened surface to 400-mb lapse rates
    may support a couple of locally stronger thunderstorms to develop
    towards early evening. Locally severe hail/wind will be the threat
    with these storms.

    ...Ohio...
    Southwesterly mid-level flow will be in place over the Ohio Valley
    and lower Great Lakes today. At the surface, an axis of low-level
    moisture will be located from eastern Kentucky into central and
    northern Ohio, where dewpoints will be in the mid to upper 60s F. As instability increases during the day, scattered thunderstorms are
    expected to develop and move northeastward across the instability
    corridor. RAP forecast soundings in central Ohio at 21Z have 0-6 km
    shear near 30 knots with 0-3 km storm-relative helicity around 150
    m2/s2. This could be enough for an isolated tornado threat.

    ..Smith/Weinman.. 05/23/2026

    $$

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  • From COD Weather Processor@1:2320/107 to wx-storm@lists.illinois.edu on Saturday, May 23, 2026 16:36:26
    ACUS01 KWNS 231636
    SWODY1
    SPC AC 231634

    Day 1 Convective Outlook
    NWS Storm Prediction Center Norman OK
    1134 AM CDT Sat May 23 2026

    Valid 231630Z - 241200Z

    ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS THE LOWER
    MISSISSIPPI VALLEY AND SOUTHERN HIGH PLAINS/WEST TEXAS...

    ...SUMMARY...
    Severe thunderstorms are possible today mainly across the Lower
    Mississippi Valley and parts of West Texas. Other more isolated
    severe storms are possible in portions of the Southeast, Ohio, and
    the central High Plains.

    ...Lower Mississippi Valley...
    An ongoing semi-well-organized cluster of storms appears to be aided
    by an MCV, and will likely continue east-northeastward today across
    the ArkLaMiss and broader parts of Mississippi, to the north of more
    extensive weaker convection closer to the coast in southern
    Louisiana. Ample heating ahead of the cluster and steepening
    low-level lapse rates will support wind potential aside from a
    modest MCV-related flow enhancement. A brief tornado could also
    occur, although thunderstorm wind damage is most probable.

    ...West Texas/Southern High Plains...
    Relatively weak mid-level flow and an ill-defined surface pattern
    aptly characterize the severe-potential setup for later today into
    the evening across this region. Residual low-level moisture and
    steep 700-500 mb lapse rates (reference the 12 UTC Midland, TX raob;
    8.7 deg C/km) in combination with strong heating will result in
    moderate instability developing by mid-late afternoon, stronger with
    southward extent across the Texas South Plains into southwest Texas.
    At least widely scattered thunderstorms are forecast to develop from
    near the Colorado/Panhandles border region southward into the
    Edwards Plateau. Isolated large hail and severe wind gusts will be
    the primary severe hazards. A gradual clustering is expected during
    the evening before this activity diminishes by late evening.

    ...Georgia/South Carolina...
    A weak mid-level disturbance will move east-northeastward today.
    Ahead of it, adequate heating of a moist boundary layer will yield
    500-1000 J/kg MLCAPE by early afternoon and scattered
    showers/thunderstorms are forecast. Deep-layer shear will support
    some multicellular organization in the form of a few thunderstorm
    clusters. The stronger water-loaded downdrafts will potentially
    yield a localized wind-damage risk during the afternoon before this
    threat wanes by early evening.

    ...Central High Plains...
    Isolated thunderstorms are expected to develop late this afternoon
    within a belt of stronger cyclonic mid-level flow associated with a north-central U.S. larger-scale mid-level trough. The 30-40 kt
    500-mb flow and steepened surface to 400-mb lapse rates may support
    a couple of locally stronger thunderstorms late this afternoon
    through early evening. Locally severe hail/wind will be the threats
    with these storms.

    ...Ohio...
    A couple of rotating storms could develop regionally this afternoon
    within a belt of residually strong low-level flow. A brief/low-end
    tornado threat may exist.

    ..Guyer/Lyons.. 05/23/2026

    $$

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  • From COD Weather Processor@1:2320/107 to wx-storm@lists.illinois.edu on Saturday, May 23, 2026 19:29:57
    ACUS01 KWNS 231929
    SWODY1
    SPC AC 231928

    Day 1 Convective Outlook
    NWS Storm Prediction Center Norman OK
    0228 PM CDT Sat May 23 2026

    Valid 232000Z - 241200Z

    ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PORTIONS OF
    THE LOWER MISSISSIPPI VALLEY AND THE SOUTHERN HIGH PLAINS...

    ...SUMMARY...
    Severe thunderstorms are possible through evening, mainly across the
    Lower Mississippi Valley and parts of West Texas. Other more
    isolated severe storms are possible in portions of the Southeast,
    Ohio, and the central High Plains.

    ...20z Update...

    The only changes to the 20z Day 1 Outlook are to remove
    probabilities across parts of TX/LA/MS in the wake of an northeastward-advancing MCS. Otherwise, forecast reasoning remains
    similar to the previous outlook, detailed below. For more detailed
    information on short term severe potential along the TX Coast and
    the central High Plains, reference MCDs 838 and 839.

    ..Leitman.. 05/23/2026

    .PREV DISCUSSION... /ISSUED 1134 AM CDT Sat May 23 2026/

    ...Lower Mississippi Valley...
    An ongoing semi-well-organized cluster of storms appears to be aided
    by an MCV, and will likely continue east-northeastward today across
    the ArkLaMiss and broader parts of Mississippi, to the north of more
    extensive weaker convection closer to the coast in southern
    Louisiana. Ample heating ahead of the cluster and steepening
    low-level lapse rates will support wind potential aside from a
    modest MCV-related flow enhancement. A brief tornado could also
    occur, although thunderstorm wind damage is most probable.

    ...West Texas/Southern High Plains...
    Relatively weak mid-level flow and an ill-defined surface pattern
    aptly characterize the severe-potential setup for later today into
    the evening across this region. Residual low-level moisture and
    steep 700-500 mb lapse rates (reference the 12 UTC Midland, TX raob;
    8.7 deg C/km) in combination with strong heating will result in
    moderate instability developing by mid-late afternoon, stronger with
    southward extent across the Texas South Plains into southwest Texas.
    At least widely scattered thunderstorms are forecast to develop from
    near the Colorado/Panhandles border region southward into the
    Edwards Plateau. Isolated large hail and severe wind gusts will be
    the primary severe hazards. A gradual clustering is expected during
    the evening before this activity diminishes by late evening.

    ...Georgia/South Carolina...
    A weak mid-level disturbance will move east-northeastward today.
    Ahead of it, adequate heating of a moist boundary layer will yield
    500-1000 J/kg MLCAPE by early afternoon and scattered
    showers/thunderstorms are forecast. Deep-layer shear will support
    some multicellular organization in the form of a few thunderstorm
    clusters. The stronger water-loaded downdrafts will potentially
    yield a localized wind-damage risk during the afternoon before this
    threat wanes by early evening.

    ...Central High Plains...
    Isolated thunderstorms are expected to develop late this afternoon
    within a belt of stronger cyclonic mid-level flow associated with a north-central U.S. larger-scale mid-level trough. The 30-40 kt
    500-mb flow and steepened surface to 400-mb lapse rates may support
    a couple of locally stronger thunderstorms late this afternoon
    through early evening. Locally severe hail/wind will be the threats
    with these storms.

    ...Ohio...
    A couple of rotating storms could develop regionally this afternoon
    within a belt of residually strong low-level flow. A brief/low-end
    tornado threat may exist.

    $$

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  • From COD Weather Processor@1:2320/107 to wx-storm@lists.illinois.edu on Sunday, May 24, 2026 00:50:01
    ACUS01 KWNS 240049
    SWODY1
    SPC AC 240048

    Day 1 Convective Outlook
    NWS Storm Prediction Center Norman OK
    0748 PM CDT Sat May 23 2026

    Valid 240100Z - 241200Z

    ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS THIS EVENING INTO
    TONIGHT ACROSS PARTS OF THE TEXAS PANHANDLE INTO WESTERN NORTH
    TEXAS...

    ...SUMMARY...
    One or two evolving clusters of thunderstorms will probably be
    accompanied by strong to locally severe wind gusts while spreading
    from the Texas Panhandle vicinity through western North Texas this
    evening into the overnight hours.

    ...01z Update...

    ...Southern Great Plains...
    Considerable thunderstorm development is generally slowly spreading
    eastward after initiating along the dryline, roughly from near
    Clovis, NM into the Midland vicinity. However, at least somewhat
    more prominent convective development continues to evolve farther to
    the north, after initiating off the higher terrain to the east of
    Raton and portions of the Sangre de Cristo Mountains. This is
    appearing to be aided by stronger, albeit still modest,
    northwesterly shear near the southern fringe of the westerlies,
    within otherwise quite weak westerly ambient deep-layer mean flow
    around or less than 10 kt, which prevails across much of the
    southern Great Plains.

    CAPE is somewhat modest as well, generally on the order of 1000-1500
    J/kg across the high plains, but the boundary-layer has become
    deeply mixed, with surface temperature-dew point spreads around or
    in excess of 30F. In the presence of the more favorable shear, the
    northern cluster has already generated a notable southeastward
    surging cold pool accompanied by strong to locally severe wind
    gusts. It appears that this will continue southeastward across much
    of the southern Texas Panhandle during the next few hours. More
    uncertainty exists later as it begins to interact with the
    convection spreading off the dryline, but at least some convection
    allowing guidance suggests that an outflow boundary intersection
    could become a focus for continuing thunderstorm development with
    strong to severe gusts into portions of western North Texas late
    this evening or overnight.

    ...Southeastern Louisiana coast...
    Low severe wind probabilities are being maintained tonight, as an
    outflow boundary remains a focus for thunderstorm development mostly
    offshore into the vicinity of southeastern coastal areas. Aided by
    inflow of high moisture content air supportive of moderately large
    CAPE, ongoing activity could still organize and intensify in the
    presence of modest shear and southwesterly ambient deep-layer mean
    flow up to around 20 kt.

    ..Kerr.. 05/24/2026

    $$

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  • From COD Weather Processor@1:2320/107 to wx-storm@lists.illinois.edu on Sunday, May 24, 2026 05:57:31
    ACUS01 KWNS 240557
    SWODY1
    SPC AC 240555

    Day 1 Convective Outlook
    NWS Storm Prediction Center Norman OK
    1255 AM CDT Sun May 24 2026

    Valid 241200Z - 251200Z

    ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS TODAY ACROSS
    PARTS OF THE SOUTHEAST AND LATE THIS AFTERNOON AND EVENING ACROSS
    PARTS OF THE CENTRAL GREAT PLAINS...

    ...SUMMARY...
    Strong thunderstorms may impact parts of the central Great Plains
    and Southeast today into tonight, accompanied by at least some risk
    for severe weather.

    ...Discussion...
    Mid/upper flow is undergoing gradual amplification across the
    northern mid-latitude Pacific. It appears that this will continue
    through this period, with a fairly significant mid-level trough and
    associated cyclone approaching the British Columbia and Pacific
    Northwest coast by late tonight. Downstream, mid-level heights will
    tend to rise across the northern Rockies and much of the Missouri
    Valley through Upper Midwest, with troughing farther east generally
    receding into the eastern Canadian provinces and adjacent portions
    of the Northeast.

    In the southern mid- to subtropical latitudes, a notable mid-level
    high is forecast to be maintained and remain centered to the
    west-southwest of Bermuda. Upstream, it appears that weak upper
    troughing will linger across eastern Texas through the western Gulf
    Basin, with perhaps an associated mid-level cyclonic circulation
    centered across the upper Texas coastal plain, as the leading edge
    of broad weak troughing emerging from the subtropical eastern
    Pacific progresses through the Southwest.

    As the stronger mid-latitude westerlies become increasingly confined
    to areas near and north of the western and central Canadian/U.S.
    border area, and the lower Great Lakes/Northeast, seasonably high boundary-layer moisture content will generally remain confined to
    the Gulf Coast states and southern Atlantic Seaboard. However,
    modest low-level moisture return appears probable along and east of
    weak lee surface troughing across the central Great Plains.

    ...Central Great Plains...
    Substantive spread remains evident within latest model output,
    including convection allowing guidance, concerning developments
    which will influence convective potential this afternoon into
    tonight. The risk for severe weather, in general, still seems
    likely to be limited by weak forcing for ascent, seasonably modest
    low-level moisture return, and modest to weak late afternoon into
    early evening deep-layer mean wind fields.

    However, due to veering of wind fields with height beneath modest
    west to northwesterly mid/upper flow, vertical shear along and east
    of the lee surface trough may become at least marginally sufficient
    for organized convection, including supercells. And any
    thunderstorm development persisting into mid/late evening may be
    augmented by a nocturnally strengthening southerly low-level jet
    (including 30-40 kt around 850 mb).

    In the presence of steep lapse rates, thermodynamic profiles
    probably will become supportive of storms capable of producing large
    hail during peak late afternoon instability into early evening,
    particularly where it appears shear may be strongest across parts of
    the middle Missouri Valley vicinity. Otherwise, widely scattered to
    scattered storms may pose a risk for strong to locally severe wind
    gusts into mid to late evening, before instability wanes and
    convection weakens.

    ...Southeast...
    Severe weather potential across the Gulf Coast states into Southeast
    today remains uncertain, with little clear signal evident in latest
    model output. However, a notable cluster of storms, which has
    weakened since becoming better organized offshore of the Louisiana
    coast earlier this evening, has generated a meso-beta scale lower/mid-tropospheric cyclonic vorticity center. It appears that
    this may migrate inland across the western Florida Panhandle
    vicinity near or shortly after daybreak, before continuing
    northeastward during the day. As it does, based on potential
    instability present in latest objective analysis, it could become a
    focus for slowly intensifying and organizing thunderstorm
    development which could eventually pose increasing potential to
    produce damaging wind gusts.

    ..Kerr/Chalmers.. 05/24/2026

    $$

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  • From COD Weather Processor@1:2320/107 to wx-storm@lists.illinois.edu on Sunday, May 24, 2026 12:43:02
    ACUS01 KWNS 241242
    SWODY1
    SPC AC 241241

    Day 1 Convective Outlook
    NWS Storm Prediction Center Norman OK
    0741 AM CDT Sun May 24 2026

    Valid 241300Z - 251200Z

    ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS TODAY ACROSS
    PARTS OF THE SOUTHEAST AND LATE THIS AFTERNOON AND EVENING FROM
    KANSAS INTO MINNESOTA...

    ...SUMMARY...
    Isolated severe thunderstorms are possible from Kansas into
    Minnesota and across portions of the Southeast today into tonight,
    accompanied by at least some risk for severe weather.

    ...Central Great Plains into MN...
    An upper trough over the Upper Midwest will move east into the Great
    Lakes with zonal flow extending east from the northern Rockies into
    the north-central states. The 12 UTC raob at Norman, OK sampled
    only a modestly moist airmass (10.5 g/kg lowest 100-mb mean mixing
    ratio) with surface stations farther north in the central Plains
    observing lower surface dewpoints than in OK. The moisture quality
    and weak forcing regime will probably limit overall storm
    coverage/intensity. However, isolated to widely scattered storms
    are forecast near a weak surface trough later this afternoon and
    evening. Vertical wind shear will support organized storms
    including the possibility for a few supercells, mainly from NE into
    MN. Large hail appears to be the primary hazard but severe gusts
    are also possible. Farther south into KS where deep-layer shear is
    forecast to be weaker, steep lapse rates will yield potential for
    isolated severe gusts with the stronger evaporatively cooled
    downdrafts.

    ...Southeast...
    Water-vapor imagery this morning shows upper troughing extending
    from the Upper Midwest southward into the northwest Gulf Coast.
    Downstream of this eastward-migrating upper feature, an MCV over
    southern AL will move northeast into GA later today and serve as the
    primary impetus for severe-weather potential. The WSR-88D VAD in
    Mobile, AL (KMOB) this morning sampled a belt of stronger 3-6 km
    flow (30-40 kt) associated with the disturbance. Seasonably rich
    low-level moisture and heating ahead of the ongoing convective
    band/cloud shield will result in moderate buoyancy by midday. This
    buoyancy and forcing for ascent will promote scattered thunderstorms
    developing in the form of linear clusters. The stronger
    water-loaded downdrafts will be capable of localized 50-65 mph gusts
    and isolated wind damage through the early evening before this
    activity subsides.

    ..Smith/Weinman.. 05/24/2026

    $$

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  • From COD Weather Processor@1:2320/107 to wx-storm@lists.illinois.edu on Sunday, May 24, 2026 16:43:03
    ACUS01 KWNS 241642
    SWODY1
    SPC AC 241641

    Day 1 Convective Outlook
    NWS Storm Prediction Center Norman OK
    1141 AM CDT Sun May 24 2026

    Valid 241630Z - 251200Z

    ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS
    SIOUXLAND/MIDDLE MISSOURI VALLEY...

    ...SUMMARY...
    Severe storms capable of hail/wind may occur across the Middle
    Missouri Valley/Siouxland later this afternoon into evening, with
    isolated severe storms also possible this afternoon/early evening
    across other parts of the central and southern Plains and Southeast.

    ...Middle Missouri Valley/Siouxland...
    Limited/late-day-arriving forcing for ascent and modest-caliber
    low-level moisture return by late May standards continues to temper
    forecast confidence details. However, overall environment and
    scenario appears to warrant a categorical Slight Risk centered on
    Siouxland given some potential for supercells capable of large hail
    later this afternoon through early/mid-evening.

    A low-amplitude shortwave trough currently over Montana will
    eventually influence the region, but generally not until this
    evening. Low-level moisture will modestly increase but be offset by
    diurnal mixing, near/east of a deepening surface low near the South Dakota/Nebraska border vicinity. Low-level convergence will maximize
    in this corridor, including northeast Nebraska/southeast South
    Dakota/far northwest Iowa and at least isolated late-day storm
    development is plausible, if not probable. If/where storms do occur,
    upwards of 35-40 kt of effective shear associated with
    west-northwesterly flow aloft would support supercells capable of
    large hail in the presence of steep lapse rates and moderate
    buoyancy. Additional and more elevated storm development over time
    is expected farther north-northeast this evening into southern
    Minnesota with some severe storms possible.

    ...Southeast States...
    An MCV across Alabama will continue to spread east-northeastward and
    influence thunderstorm development across Georgia toward South
    Carolina and the southern Appalachians. The boundary layer will
    continue to destabilize this afternoon and support the possibility
    of isolated wind damage with the more robust storm development this
    afternoon.

    ...North/central Texas...
    Per visible satellite, ample insolation and heating of a moist
    boundary layer will occur in the southern/eastern periphery of a
    remnant mid-level low. While low/mid-tropospheric winds will remain
    weak, sufficient heating and steep low-level lapse rates may support
    some strong/locally severe pulse-type storms capable of downbursts,
    and possibly a couple of instances of hail.

    ..Guyer/Lyons.. 05/24/2026

    $$

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  • From COD Weather Processor@1:2320/107 to wx-storm@lists.illinois.edu on Sunday, May 24, 2026 19:49:35
    ACUS01 KWNS 241949
    SWODY1
    SPC AC 241948

    Day 1 Convective Outlook
    NWS Storm Prediction Center Norman OK
    0248 PM CDT Sun May 24 2026

    Valid 242000Z - 251200Z

    ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS OVER PARTS OF
    NORTHEAST NEBRASKA...SOUTHEASTERN SOUTH DAKOTA...NORTHWEST IOWA AND
    SOUTHWEST MINNESOTA...

    ...SUMMARY...
    Severe storms capable of hail/wind may occur across the Middle
    Missouri Valley/Siouxland later this afternoon into evening, with
    isolated severe storms also possible this afternoon/early evening
    across other parts of the central and southern Plains and Southeast.

    ...20z Update...
    No major changes were made to the prior outlook. Isolated to widely
    scattered thunderstorms, with a few supercells, appear probable
    across parts of the central High plains/Midwest late this afternoon
    into this evening. Moderate buoyancy and 35-40 kt of effective shear
    associated with west-northwesterly flow aloft could support
    supercells capable of large hail in the presence of steep lapse
    rates.

    Elsewhere, moderate to strong buoyancy and weak shear will
    predominate. Scattered thunderstorms over much of the Southeast and North/central TX will be capable of sporadic damaging gusts with
    downbursts. 5% wind probabilities were expanded slightly over parts
    of north TX where some convective clustering may occur along a prior
    outflow boundary and ahead of a weak MCV. Otherwise, see the
    previous discussion for more information.

    ..Lyons.. 05/24/2026

    .PREV DISCUSSION... /ISSUED 1141 AM CDT Sun May 24 2026/

    ...Middle Missouri Valley/Siouxland...
    Limited/late-day-arriving forcing for ascent and modest-caliber
    low-level moisture return by late May standards continues to temper
    forecast confidence details. However, overall environment and
    scenario appears to warrant a categorical Slight Risk centered on
    Siouxland given some potential for supercells capable of large hail
    later this afternoon through early/mid-evening.

    A low-amplitude shortwave trough currently over Montana will
    eventually influence the region, but generally not until this
    evening. Low-level moisture will modestly increase but be offset by
    diurnal mixing, near/east of a deepening surface low near the South Dakota/Nebraska border vicinity. Low-level convergence will maximize
    in this corridor, including northeast Nebraska/southeast South
    Dakota/far northwest Iowa and at least isolated late-day storm
    development is plausible, if not probable. If/where storms do occur,
    upwards of 35-40 kt of effective shear associated with
    west-northwesterly flow aloft would support supercells capable of
    large hail in the presence of steep lapse rates and moderate
    buoyancy. Additional and more elevated storm development over time
    is expected farther north-northeast this evening into southern
    Minnesota with some severe storms possible.

    ...Southeast States...
    An MCV across Alabama will continue to spread east-northeastward and
    influence thunderstorm development across Georgia toward South
    Carolina and the southern Appalachians. The boundary layer will
    continue to destabilize this afternoon and support the possibility
    of isolated wind damage with the more robust storm development this
    afternoon.

    ...North/central Texas...
    Per visible satellite, ample insolation and heating of a moist
    boundary layer will occur in the southern/eastern periphery of a
    remnant mid-level low. While low/mid-tropospheric winds will remain
    weak, sufficient heating and steep low-level lapse rates may support
    some strong/locally severe pulse-type storms capable of downbursts,
    and possibly a couple of instances of hail.

    $$

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  • From COD Weather Processor@1:2320/107 to wx-storm@lists.illinois.edu on Monday, May 25, 2026 00:54:05
    ACUS01 KWNS 250054
    SWODY1
    SPC AC 250052

    Day 1 Convective Outlook
    NWS Storm Prediction Center Norman OK
    0752 PM CDT Sun May 24 2026

    Valid 250100Z - 251200Z

    ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS THIS EVENING
    ACROSS PARTS OF NORTHEASTERN NEBRASKA...SOUTHEASTERN SOUTH DAKOTA...NORTHWESTERN IOWA...SOUTHWESTERN MINNESOTA...

    ...SUMMARY...
    Isolated supercell development may persist in a narrow corridor
    across northeastern Nebraska into southwestern Minnesota through mid
    to late evening before diminishing.

    ...01Z Update...

    ...Mid Missouri Valley...
    Mid-level heights continue to build across much of the northern
    Rockies and Missouri Valley into Upper Midwest. Primary forcing for
    ongoing convective development appears to lift associated with weak lower/mid-tropospheric warm advection, along and east of weak
    northern Great Plains surface troughing. Low-level moisture return
    has remained rather modest (with maximum surface dew points still in
    the mid/upper 50s F) and confined to a narrow corridor, but this
    appears to be contributing to CAPE on the order of 1000-2000 J/kg.
    The onset of radiational surface cooling, coupled with warming
    aloft, probably will result in rapidly increasing inhibition within
    the next couple of hours. This should be accompanied by diminishing
    convective trends, but it is possible that this could be slowed
    somewhat by forcing on the nose of a nocturnally strengthening
    low-level jet.

    ...Southern Appalachians...
    As a remnant lower/mid-tropospheric mesoscale convective vortex
    migrates north-northeastward across northwestern Georgia into the
    southern Appalachians, modest clockwise-curved low-level hodographs
    are developing across the Piedmont of eastern Georgia into South
    Carolina. This is where a recent increase in thunderstorm
    development is ongoing in the presence of a seasonably moist
    boundary-layer characterized by sizable CAPE. With the surface dew
    points in the lower 70s enhancing low-level buoyancy and potential
    near surface upward accelerations, an isolated tornado may not be
    out of the question, before forcing spreads into cooler/more stable
    air.

    ..Kerr.. 05/25/2026

    $$

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