Subj : DAY1SVR: Day 1 Convective Outlook To : wx-storm@lists.illinois.edu From : COD Weather Processor Date : Thu Sep 04 2025 05:54:03 ACUS01 KWNS 040552 SWODY1 SPC AC 040550 Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 1250 AM CDT Thu Sep 04 2025 Valid 041200Z - 051200Z ....THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS IN PARTS OF THE EAST... ....SUMMARY... Isolated damaging winds are possible across parts of the Northeast to the southern Appalachians and Tennessee Valley from late morning through the afternoon. ....Synopsis... A vertically stacked cyclone will drift north in northern ON, as an intense mid-level jetlet and shortwave trough amplifies from the southern Canadian Prairies across the Upper Midwest/Great Lakes. A leading cold front will progress east into the Northeast to TN Valley by this afternoon, with a separate lee trough diurnally sharpening from VA into NY. ....Southern Appalachians/TN Valley to the Northeast... Convection will likely be ongoing at 12Z along parts of the aforementioned cold front from the Lake Erie to northern KY vicinity. Despite weak mid-level lapse rates, diabatic surface heating ahead of this activity should yield diurnal increases in convective coverage/intensity by late morning across parts of the Cumberland Plateau. This will overlap the northern extent of moderate buoyancy across the TN Valley where low-level moisture is richer. Combined with a more westerly component to mid-level flow near the basal portion of the broad trough, a few semi-discrete and loosely organized cells should develop southward during the afternoon. Locally damaging winds and marginally severe hail are possible, centered on the eastern TN vicinity. Isolated to scattered multicell clusters and short-line segments may also evolve in the afternoon from convection along/ahead of the cold front and lee trough. Weak MLCAPE and poor mid-level lapse rates will temper convective vigor, with damaging wind potential locally augmented where pockets of deeper boundary-layer heating occur. ....Mid-MO Valley... The aforementioned shortwave trough and intense mid-level jetlet amplifying into the Upper Midwest could support a couple brief strong storms in the early evening. A narrow corridor of meager surface-based buoyancy may develop ahead of a sharpening cold front by late afternoon. Modified moisture return in the wake of a prior frontal passage will be limited and convection should remain low-topped given the flimsy buoyancy. Still, the background wind fields and strengthening forcing for ascent render concern for a few locally strong gusts and small hail. ....KS... An accelerating and sharpening cold front will sweep south across the central High/Great Plains tonight. Undercut/elevated convection should form to the cold side of this boundary early Friday morning. Locally strong surface gusts may accompany this activity amid robust low-level northerlies. ...Grams/Thornton.. 09/04/2025 $$ = = = 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) .