ACUS11 KWNS 180140
SWOMCD
SPC MCD 180139=20
ILZ000-MOZ000-180345-

Mesoscale Discussion 0486
NWS Storm Prediction Center Norman OK
0839 PM CDT Fri Apr 17 2026

Areas affected...parts of east central Missouri into adjacent
portions of Illinois

Concerning...Tornado Watch 131...

Valid 180139Z - 180345Z

The severe weather threat for Tornado Watch 131 continues.

SUMMARY...An organized cluster of storms may be maintained across
northwestern portions of Greater St. Louis through 9-11 PM CDT, with
a continuing risk for damaging wind gusts and potential for a brief
tornado or two.

DISCUSSION...A sustained cluster of thunderstorms has become
increasingly organized across and east of the Missouri Ozarks during
the past few hours, with a well-defined lower/mid-tropospheric
cyclonic circulation and associated evolving bow echo structure in
radar reflectivities. It appears that the apex of the bow structure
has accelerated east-northeastward in excess of 50 kt. If this
motion is maintained, it is on track to surge across northwestern
portions of Greater St. Louis through 02-03Z.=20=20

This still appears to be perhaps just ahead of the leading edge of
the surface cold front, as delineated by 2-4 mb 2-hourly surface
pressures rises now east of Quincy IL south/southwestward through
the Columbia and Sedalia vicinities. The boundary-layer has
undergone warming and drying across the St. Louis area, where the temperature/dew point at Lambert is 81/57 F. However, thermodynamic
profiles still appear sufficiently unstable to maintain convection
with potential to produce damaging wind gusts. The risk for
tornadoes is more unclear, but the environment might still be
conducive immediately to the north of the front.

..Kerr.. 04/18/2026

...Please see https://urldefense.com/v3/__http://www.spc.noaa.gov__;!!DZ3fj= g!_-IaHPR69aozguV_ow7w4RUxVGiuxefso7jyeUWhIcKDNUWRhlxmqfEWt-zKPBeEwfqU76j7c= Tpi2eFffEIGMFQ-mdc$ for graphic product...

ATTN...WFO...ILX...LSX...SGF...

LAT...LON 38949180 39509044 39838933 39098870 38458965 38069075
38029216 38409185 38949180=20

MOST PROBABLE PEAK WIND GUST...65-80 MPH
MOST PROBABLE PEAK HAIL SIZE...1.00-1.75 IN


=3D =3D =3D
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