Subj : DAY3SVR: Nws Storm Prediction Center Norman Ok To : wx-storm@lists.illinois.edu From : COD Weather Processor Date : Tue Sep 09 2025 07:32:12 ACUS03 KWNS 090732 SWODY3 SPC AC 090730 Day 3 Convective Outlook NWS Storm Prediction Center Norman OK 0230 AM CDT Tue Sep 09 2025 Valid 111200Z - 121200Z ....NO SEVERE THUNDERSTORM AREAS FORECAST... ....SUMMARY... Isolated thunderstorms are possible across Montana and the Dakotas, as well as the southern High Plains and Intermountain West Thursday. Uncertainty on storm coverage/intensity remains high. ....Synopsis... A broad upper low over the Great Basin is forecast to slowly drift eastward Thursday with several smaller shortwaves passing through it. An embedded perturbation along the eastern flank of the low will accompany a mid-level jet over portions of the northern Rockies and Plains. This will help deepen a lee cyclone and trailing lee trough much of the High Plains. ....Montana and western Dakotas... As the upper low gradually edges closer, an embedded shortwave trough and mid-level jet will pass over the northern Rockies and Plains Thursday afternoon. The surface low over central MT should deepen, increasing low-level southeasterly flow. A warm front, extending southeastward from the surface low, will gradually lift northward with 60+ F dewpoints in its wake over the northern High Plains. Modest low-level convergence along the trailing lee trough and near a weak cold front emanating from the low could support isolated storms over eastern MT and the western Dakotas. With sufficient buoyancy and increasing flow aloft from the upper jet, some potential for organized multicells or transient supercells is apparent. However, model solutions vary considerable on the degree of capping and resulting storm development. Given these uncertainties, no severe probabilities will be added currently, though some risk for severe gusts and hail could be needed in future updates. ....Central and Southern High Plains... Farther south, the lee trough may serve as a focus for isolated storm development Thursday afternoon amidst strong heating and increasing low-level moisture over the central and southern High Plains. However, forcing for ascent beneath the shortwave ridge appears weak as the main trough and shortwave are likely to remain over the Rockies and Four Corners where low-level moisture is modest. While isolated high-based storms could develop and pose a risk for locally gusty winds, confidence in a broader severe risk is low. ...Lyons.. 09/09/2025 $$ = = = 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) .