ACUS11 KWNS 180319
SWOMCD
SPC MCD 180319=20
MIZ000-INZ000-ILZ000-180515-

Mesoscale Discussion 0488
NWS Storm Prediction Center Norman OK
1019 PM CDT Fri Apr 17 2026

Areas affected...Eastern Illinois into western Indiana

Concerning...Tornado Watch 131...133...

Valid 180319Z - 180515Z

The severe weather threat for Tornado Watch 131, 133 continues.

SUMMARY...Severe winds and QLCS tornadoes will remain possible for
the next couple of hours across eastern Illinois and into western
Indiana. However, the early stages of a weakening trend are noted,
suggesting that the severe threat should gradually wane with time.

DISCUSSION...Over the past hour, several severe wind reports have
been noted with an organized squall line as it moved across central
IL. However, the early stages of a weakening trend are noted with
the line across several metrics, including MRMS VIL, GOES IR
cloud-top temperatures, and lightning counts. This weakening has
been anticipated by recent high-res guidance during the 04-06 UTC
period as the line migrates out of the primary buoyancy axis and
into a drier air mass located downstream across central IN. The
noted convective trends seem to be affirming these short-term
forecasts, so further weakening appears likely as the line continues
east. However, VWP observations downstream at KIND show an uptick in
low-level wind shear with 0-1 km SRH recently increasing to around
550 m2/s2. This highly favorable low-level wind environment will
continue to support the potential for severe winds and embedded QLCS
tornadoes within the line at least for the next couple of hours as
it crosses into western IN. How long this threat will persist
downstream remains somewhat unclear given the ongoing weakening
trend.

..Moore.. 04/18/2026

...Please see https://urldefense.com/v3/__http://www.spc.noaa.gov__;!!DZ3fj= g!6b9rBl3k8EhYBWsYdqcFeP6nIjpjhySKACMG8qz82acyA1zTCze4q6ANqRjX_wr7wcdquw4eC= j1K4ySfOW2RSDaSwiA$ for graphic product...

ATTN...WFO...IWX...IND...LOT...ILX...

LAT...LON 39648873 40008822 40568796 41058788 41308788 41618782
41788763 41798743 41788716 41838695 41918677 41868585
41718569 41418570 40958589 40518615 39948655 39508699
39428736 39418797 39518854 39648873=20

MOST PROBABLE PEAK TORNADO INTENSITY...85-115 MPH
MOST PROBABLE PEAK WIND GUST...65-80 MPH
MOST PROBABLE PEAK HAIL SIZE...UP TO 1.25 IN


=3D =3D =3D
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