Subj : DAY1SVR: Day 1 Convective Outlook To : wx-storm@lists.illinois.edu From : COD Weather Processor Date : Tue Aug 12 2025 11:51:41 ACUS01 KWNS 121150 SWODY1 SPC AC 121148 Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0648 AM CDT Tue Aug 12 2025 Valid 121300Z - 131200Z ....THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF THE UPPER GREAT LAKES/MIDWEST...AND PORTIONS OF THE SOUTHWEST... ....SUMMARY... Strong to occasionally severe thunderstorms may impact parts of the upper Great Lakes/Midwest today with both damaging winds and hail possible. Gusty winds may also occur over southeast Arizona and southwest New Mexico. ....Great Lakes/Midwest... A band of thunderstorms associated with an MCV tracked northeastward across parts of IA into northern IL and southern WI early this morning while remaining mostly sub-severe. Still, there may be some potential for strong to locally damaging winds with this activity as it continues northeastward across Lake Michigan into parts of Lower MI this morning/early afternoon as daytime heating gradually destabilizes the boundary layer. Otherwise, additional convection should develop later this afternoon along/ahead of a weak front over parts of WI and the U.P. of MI as the southern portion of a mid/upper-level trough moves eastward over the Upper Midwest/Great Lakes. Instability is forecast to remain fairly modest ahead of the front, but enough deep-layer shear should exist to support some organized convection. Initial cells may be capable of producing marginally severe hail, before clustering potentially increases the threat for occasional strong to damaging winds. A separate area of thunderstorms is forecast to develop this afternoon farther south and ahead of the front from portions of the Midwest into Lower MI. While this region will have relatively weaker mid-level westerly flow and related deep-layer shear compared to locations farther north, greater low-level moisture and instability are expected to be present. As low-level lapse rates become steepened with diurnal heating of the moist airmass, loosely organized clusters may become capable of producing isolated damaging winds as they spread generally east-northeastward through the afternoon and early evening. ....Southwest... Strong daytime heating should encourage diurnally driven convection over the higher terrain of southeast AZ and southwest NM this afternoon. With weak flow aloft and negligible shear, thunderstorms should drift slowly southward. Still, occasional gusty winds may occur with the more robust convection given steepened lapse rates. ...Gleason/Leitman.. 08/12/2025 $$ = = = 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) .