Subj : DAY3SVR: Nws Storm Prediction Center Norman Ok To : wx-storm@lists.illinois.edu From : COD Weather Processor Date : Sat Jul 26 2025 19:16:49 ACUS03 KWNS 261915 SWODY3 SPC AC 261915 Day 3 Convective Outlook NWS Storm Prediction Center Norman OK 0215 PM CDT Sat Jul 26 2025 Valid 281200Z - 291200Z ....THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS PORTIONS OF MONTANA...THE DAKOTAS...IOWA...MINNESOTA...AND WISCONSIN... ....SUMMARY... Severe thunderstorms are possible from the northern Rockies into the Dakotas and Upper Midwest. ....Southeast Montana and the Dakotas to Wisconsin... A couple of shortwave impulses are forecast to move eastward through westerly flow aloft on Sunday. At the surface, low pressure is forecast over SD, with a surface front expected to develop south/southeast from southeast MT to the Mid-MO Valley into early Monday. A very moist airmass will be in place ahead of the surface low/front across SD into parts of MN/IA/WI. This will support a broad area of strong to extreme instability. However, uncertainty persists, and is mainly a result of how convection and a potential MCS will develop in the Day 2/Sunday period and what impacts those storms may have on the boundary layer across parts of the Upper Midwest. Nevertheless, it appears likely isolated storms will develop near the surface low and within the post-frontal regime from southeast MT into the Black Hills vicinity. This activity will pose a risk of mainly strong/severe gusts and perhaps some marginal hail. With eastward extent across SD into MN/IA/WI, storms will likely form along the southward-advancing front. Some guidance depicts a modest low-level jet developing during the evening. Coupled with sufficient effective shear, and strong instability, upscale growth into an MCS is possible. Where this may occur is uncertain as previously mentioned outflow from prior convection may result in lingering inhibition. Some severe wind risk appears possible and the Marginal risk (level 1 of 5) will be maintained, though higher probabilities may be needed in subsequent outlooks. ....Central MT... Isolated thunderstorms will develop over higher terrain during the afternoon/evening as a shortwave trough migrates through the upper ridge over the Pacific Northwest. Sufficient moisture will be in place and relatively cool temperatures aloft will aid in MLCAPE values approaching 1000 J/kg. Effective shear magnitudes around 25-30 kt will support occasionally organized cells. A deeply mixed boundary layer will foster locally strong/damaging wind potential. ...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) .