Subj : DAY1SVR: Enhanced Risk To : All From : Mike Powell Date : Wed Jul 12 2023 17:30:00 ACUS01 KWNS 122002 SWODY1 SPC AC 122000 Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0300 PM CDT Wed Jul 12 2023 Valid 122000Z - 131200Z ....THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF NORTHERN ILLINOIS/FAR NORTHWESTERN INDIANA...AND PARTS OF EASTERN KANSAS INTO MISSOURI... ....SUMMARY... Severe thunderstorms remain possible across much of Missouri, Illinois, and adjacent portions of the central Plains and Midwest this afternoon through tonight. A few tornadoes should occur this afternoon and evening across parts of northern Illinois into far northwestern Indiana, with a strong tornado possible. Otherwise, damaging winds and large hail should occur with intense thunderstorms that develop, with some potential for significant (75+ mph) severe winds and very large hail across parts of Missouri and Kansas. ....20Z Update... Primary change with this update was to introduce higher tornado probabilities in a narrow corridor across northern IL and far northwestern IN, including Chicago. Recent VWPs from KLOT show impressive low-level shear (0-1 km 35-40+ kt) and enlarged/curved low-level hodographs associated with a focused low-level jet. In the wake of a remnant MCS and lessening precipitation shield, it appears increasingly likely based on recent visible satellite imagery and surface observations that sufficient destabilization to support surface-based convection will occur across this region over the next few hours. Given the very favorable low-level and deep-layer shear available, concern has increased that any supercell which forms in this environment will be capable of producing a tornado. Some potential will exist for a strong tornado as effective SRH strengthens to around 250-350 m2/s2 along/near the developing warm front. The Slight Risk has also been expanded northward in southern Lower MI to account for a small bowing cluster which may develop. No changes have been made to the Enhanced Risk across parts of eastern KS into MO. 18Z sounding from TOP showed warm low/mid-level temperatures and a cap which should continue to inhibit robust convection for at least a couple more hours. Still, intense thunderstorm development is expected later this evening in tandem with a modestly strengthening low-level jet. ...Gleason.. 07/12/2023 ..PREV DISCUSSION... /ISSUED 1140 AM CDT Wed Jul 12 2023/ ....Northern IL/southern WI east to northwest OH/southern lower MI... Current MCS continues a general weakening trend based on IR cloud tops, radar trends and recent reports. Air mass recovery in the wake of the morning convection currently appears plausible, aided by a modestly enhanced low-level jet later this afternoon and evening. Steepening mid-level lapse rates will contribute to moderate/pockets of strong MLCAPE this afternoon, and coupled with 40-50 kts of deep-layer shear would result in a favorable parameter space for supercell development by late afternoon/early evening with all severe hazards possible. Will introduce a small 5 percent tornado probability area across this region, where forecast sounding hodograph structure appears most favorable for low-level rotation/tornado potential east of a weak surface low. ....KS/MO/OK this evening... Redevelopment of severe storms appears probable late this afternoon/early evening in the vicinity of an outflow boundary that continues to slow its southward motion across northern portions of KS/MO. Strong/locally extreme MLCAPE is anticipated near/south of this boundary with substantial shear in the cloud-bearing layer. Storms that develop will likely initially possess supercell characteristics with severe hail (possibly significant) and wind, with eventual upscale growth into one or two MCSs capable of potentially significant severe gusts. The Enhanced Risk area has been reoriented based on expected outflow boundary location later this afternoon and a consensus of 12z CAM guidance/HREF ensemble max probabilities. ....IN/OH into New England... A surface quasistationary front currently extends from northern IN into NY and New England. Substantial heating is underway east of the front, which should allow for destabilization and scattered afternoon thunderstorm development. This area lies along the southern fringe of stronger west/southwesterly flow aloft, with 25-35 knots of deep-layer shear. This may be sufficient for a few strong storms later today capable of gusty/damaging winds. $$ --- SBBSecho 3.14-Linux * Origin: Ilink: CCO - capitolcityonline.net (454:1/105) .