Subj : DAY2SVR: Nws Storm Prediction Center Norman Ok To : wx-storm@lists.illinois.edu From : COD Weather Processor Date : Sat Jul 26 2025 17:34:10 ACUS02 KWNS 261733 SWODY2 SPC AC 261732 Day 2 Convective Outlook NWS Storm Prediction Center Norman OK 1232 PM CDT Sat Jul 26 2025 Valid 271200Z - 281200Z ....THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PORTIONS OF MN...WI...AND UPPER MI... ....SUMMARY... Severe thunderstorms are possible across the Upper Midwest, as well as across portions of the Mid-Atlantic and New England region. ....Upper Midwest... Uncertainty still exists for Sunday's forecast, driven by convection in the Day 1/Saturday period persisting into parts of MN early in the forecast period. However, forecast guidance is consistent in bringing an upper shortwave trough across MN/WI/Upper MI, with 40-60 kt 500 mb westerly flow overspreading the region coincident with the shortwave feature. At the surface, a very moist airmass will be in place with dewpoints mostly in the 70s. This will support a corridor of strong to extreme instability (MLCAPE 3000-5000 J/kg from western SD into MN and portions of northern WI/Upper MI). A weak surface front/trough will develop east/southeast through the period and may intersect outflow from morning activity. This should focus thunderstorm develop/re-intensification as the airmass rapidly destabilizes/recovers ahead of or in the wake of any lingering early morning thunderstorm activity. While the spatial extent of greater severe potential remains a bit uncertain, the best consistency across multiple forecast models suggests severe/damaging wind potential will be greater across parts of MN/northern WI and parts of Upper MI. A Slight risk (level 2 of 5) has been included to account for latest trends in guidance and an overall favorable synoptic/mesoscale pattern for an organized line of convection producing damaging gusts. Convection may persist downstream during the evening/nighttime hours into IA/IL/southern WI, but uncertainty is greater in these areas, so the Marginal risk (level 1 of 5) has been maintained. ....Mid-Atlantic Vicinity... A couple of shortwave impulses are expected to move through northwesterly flow aloft across the Mid-Atlantic vicinity Sunday morning/afternoon. Deep shear will remain weak, with only around 15-25 kt northwesterly flow depicted in forecast soundings. Nevertheless, a very moist airmass with dewpoints in the 70s and PW values over 2 inches, will be in place across the region. This will support strong instability in the 2000-3000 J/kg MLCAPE range. Where strong heating occurs, steepening low-level lapse rates are noted in forecast soundings. Thunderstorms are expected to develop over higher terrain as a weak surface boundary sags southward. Additional convection may develop along a surface trough across the VA/NC Piedmont. Isolated strong/damaging gusts associated with wet downbursts will be possible as storms develop south/southeast through early evening. ...Leitman.. 07/26/2025 $$ = = = 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) .