Subj : DAY1SVR: Day 1 Convective Outlook To : wx-storm@lists.illinois.edu From : COD Weather Processor Date : Tue May 20 2025 19:54:38 ACUS01 KWNS 201954 SWODY1 SPC AC 201952 Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0252 PM CDT Tue May 20 2025 Valid 202000Z - 211200Z ....THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS FOR PORTIONS OF THE MID MS VALLEY TO THE CENTRAL APPALACHIANS... ....SUMMARY... Multiple rounds of severe thunderstorms are expected today through this evening, centered on the Mid/Deep South, Tennessee/Lower Ohio Valleys, and Cumberland Plateau. Tornadoes, some of which could be strong, along with scattered to widespread damaging winds, and large to isolated significant severe hail will be possible. ....20Z Update... Much of the previous forecast remains on track. Earlier storms across the TN Valley have matured into a QLCS, which is now approaching the central Appalachians. These storms should progress toward the eastern extent of a buoyant warm sector with a continued risk of damaging gusts and perhaps a couple of tornadoes. Storms poised to cross the MS River over the central MS Valley, and more discrete storms farther east over western TN/northern MS, should intensify further as they move eastward amid a strongly sheared and unstable airmass. The more intense, discrete storms will be capable of large to very large hail and at least isolated tornadoes. The more dominant supercells that move into northeast MS, middle TN, and southern KY, where surface is flow is relatively more backed, will have the best chance at producing a strong tornado. Lastly, storms should continue to intensify ahead of a surface low over central IL and immediate surrounding areas. Shear/buoyancy over this region favors supercell structures with a continued large hail/tornado risk. ...Squitieri.. 05/20/2025 ..PREV DISCUSSION... /ISSUED 1115 AM CDT Tue May 20 2025/ ....KY/TN... Thunderstorms are ongoing across central KY/middle TN. These storms will progress eastward through the afternoon into a moist and increasingly unstable air mass over eastern KY/TN and eventually into western WV/VA. Most model guidance suggests that storms will intensify through the day, with an increasing risk of damaging wind gusts and a few tornadoes. Refer to MCD #902 for further details. ....AR into the TN Valley this afternoon/evening... In the wake of the aforementioned convection, rapid heating is occurring across eastern AR/west TN/northern MS. Surface dewpoints in the upper 60s to 70s and steep mid level lapse rates will yield afternoon MLCAPE values around 3000 J/kg and only a weak cap. This will lead to the development of multiple clusters of intense thunderstorms (including supercells) that will track eastward through the afternoon and evening hours. The initial storms will pose a risk of very large hail and a few tornadoes. As the activity progresses eastward, the risk of damaging winds will increase with a persistent risk of tornadoes. Strong tornadoes will be possible. Storms are expected to get as far east as northwest GA tonight before slowly weakening. ....MO/IL... Satellite imagery shows a well-defined shortwave trough and associated surface low over IA/MO. Ahead of this feature, southerly low-level winds have transported mid 60s dewpoints into central IL, where strong heating is now occurring. This will result in moderate CAPE across the region and encourage rapid thunderstorm development over northeast and east-central MO by mid-afternoon. Steep lapse rates aloft and favorable deep-layer shear will support supercell structures capable of large hail, damaging winds, and a few tornadoes. Storms will track across IL and into central IN this evening. $$ = = = To unsubscribe from WX-STORM and you already have a login, go to https://lists.illinois.edu and use the "Unsubscribe" link. Otherwise email Chris Novy at cnovy@cox.net and ask to be removed from WX-STORM. --- SBBSecho 3.20-Linux * Origin: capitolcityonline.net * Telnet/SSH:2022/HTTP (1:2320/105) .