Subj : DAY1SVR: Day 1 Convective Outlook To : wx-storm@lists.illinois.edu From : COD Weather Processor Date : Tue Aug 27 2024 05:40:15 ACUS01 KWNS 270540 SWODY1 SPC AC 270538 Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 1238 AM CDT Tue Aug 27 2024 Valid 271200Z - 281200Z ....THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS THE GREAT LAKES AND PORTIONS OF THE MIDWEST... ....SUMMARY... Severe thunderstorms are possible across the Great Lakes region and portions of the Midwest. A lower risk for a few strong/severe storms will extend southwest across the lower Missouri Valley into northern Kansas. ....Great Lakes/Midwest... Seasonally strong short-wave trough is advancing into the northern High Plains early this morning. This feature is forecast to shift into the eastern Dakotas by 18z as a 500mb speed max translates across southern MN. Gradual deamplification is expected during the latter half of the period as the short wave ejects across the upper Great Lakes. At the surface, primary synoptic boundary is forecast to extend across the eastern U.P. of MI-central WI-central IA-southern NE at the start of the period. Westerly flow will deepen across the Great Lakes region by midday, and this will encourage the surface front to shift downstream as west-southwesterly LLJ strengthens across southern WI/Lower MI. Long-lived, mature MCS is currently propagating across northern/central WI, in line with latest HREF guidance. This complex of storms will track across northern Lake MI into Lower MI later this morning as it turns southeast. Convective outflow will likely influence subsequent thunderstorm development ahead of the short wave/surface front. Latest thinking is modest boundary-layer heating will extend across northern IL into extreme southern WI, east into the northern OH Valley region. This will be the northern extent of a very unstable airmass which should support afternoon thunderstorm development/intensification. It's not entirely clear where the early-day outflow will establish itself, and uncertainty necessitates some caution trying to focus higher severe probabilities. Even so, there may be a need to expand SLGT risk a bit south if the boundary advances further than currently expected. Severe gusts and hail are the primary risks with convection today. Farther southwest across the lower MO Valley into northern Kansas, very strong surface heating will negate CINH and convective temperatures will be easily breached as readings rise through the mid 90s. Isolated-scattered thunderstorms may focus along the synoptic front, though this activity will evolve within a vertical wind profile that is fairly weak and supports mostly pulse to multicell updrafts. In the absence of any short-wave trough, surface heating will prove instrumental in thunderstorm development, and the lack of a strong LLJ may also be a limiting factor in upscale growth. ...Darrow/Squitieri.. 08/27/2024 $$ = = = 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) .