ACUS11 KWNS 180319 SWOMCD SPC MCD 180319 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 www.spc.noaa.gov 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 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