Subj : DAY1SVR: Day 1 Convective Outlook To : wx-storm@lists.illinois.edu From : COD Weather Processor Date : Fri Aug 15 2025 05:35:58 ACUS01 KWNS 150534 SWODY1 SPC AC 150532 Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 1232 AM CDT Fri Aug 15 2025 Valid 151200Z - 161200Z ....THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PORTIONS OF THE NORTHERN PLAINS AND UPPER MISSISSIPPI VALLEY... ....SUMMARY... Scattered severe storms are likely over parts of the northern Plains and Upper Mississippi Valley. ....Northern Plains/Upper MS Valley... Broad anticyclonic flow is forecast to continue across the central/southern Plains during the day1 period. Stronger 500mb flow will extend around the periphery of this feature, extending from the northern Rockies-northern Plains-upper Great Lakes. While a few disturbances will eject across the northern Rockies toward the upper MS Valley, latest model guidance suggests heights will actually rise much of the period. One such feature currently extends from eastern WY into northeast CO. Scattered thunderstorms are noted immediately downstream from the Black Hills into western NE. This disturbance should advance into central SD by the start of the period, then into MN by early afternoon. While a few strong storms may be ongoing at the start of the period, renewed development is expected during the afternoon across the upper MS Valley. LLJ is forecast to increase a bit into southwest MN ahead of the short wave, and this should encourage robust convection along a front that will be draped from southwest MN-northern WI. Strong buoyancy will be noted south of the front across much of this region and MLCAPE could exceed 3000 J/kg from MN/IA into SD/NE. While the short wave should encourage organized convection, boundary-layer heating will prove instrumental in thunderstorm development. Forecast soundings suggest CINH weakens considerably by 19-21z and convection should expand in areal coverage as convective temperatures are breached. Wind/hail are the primary risks, though a brief tornado can not be ruled out with any supercell structures. Farther west, convective temperatures will be breached across eastern WY by 22z. Scattered storms will once again develop over the higher terrain/Plains then spread downstream into western SD/northwestern NE during the evening. Some consideration was given to a SLGT risk for this activity but the short-wave trough that should affect this region will eject across northern AZ into southwest WY around 16/00z. Timing of this feature suggests stronger support will not affect this region until well after sunset. ...Darrow/Lyons.. 08/15/2025 $$ = = = 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 3.28-Linux * Origin: capitolcityonline.net * Telnet/SSH:2022/HTTP (1:2320/105) .