Subj : DAY1SVR: Day 1 Convective Outlook To : wx-storm@lists.illinois.edu From : COD Weather Processor Date : Fri Jul 18 2025 05:48:45 ACUS01 KWNS 180546 SWODY1 SPC AC 180545 Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 1245 AM CDT Fri Jul 18 2025 Valid 181200Z - 191200Z ....THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS IN PARTS OF VA/NC AND NE/SD/MN/IA... ....SUMMARY... Scattered severe thunderstorms with large hail, damaging winds, and a few tornadoes are possible across parts of the Corn Belt in Iowa, Minnesota, Nebraska, and South Dakota this evening into tonight. Scattered damaging winds are possible across parts of Virginia and northern North Carolina this afternoon. ....SD/MN/IA/NE... A low-amplitude shortwave impulse along the international border over the northern Great Plains will progress across the Upper Midwest/Great Lakes and ON. A belt of seasonably strong mid-level westerlies should be centered this afternoon from central MN to Lake Huron. Elevated convection is expected to be ongoing at 12Z across parts of the eastern Dakotas into northern MN ahead of the mid-level impulse, amid a low-level warm theta-e advection regime. As this overspreads a preceding cool/dry surface airmass over the Upper Midwest, pronounced differential diabatic surface heating will strengthen a baroclinic zone across southeast SD bisecting IA to the southeast by late afternoon. Thunderstorm development in this time frame should be confined to along/northeast of the surface warm front across far eastern SD and southern MN. Large-scale ascent appears nebulous, but a strengthening low-level jet should aid in convection flanking to the southwest across the Mid-MO Valley during the evening. This may merge with high-based convection shifting east from western NE. Deep-layer shear will be sufficient for initial supercells that will probably grow upscale into multiple clusters and/or an MCS tonight. The latter may accelerate east-southeast for a time in the western IA vicinity before weakening during the early morning. A mix of all severe hazards are possible in this setup with hail being favored early and wind later. Moderately enlarged low-level hodographs should also support a tornado threat with any sustained supercell to QLCS evolution. ....VA/NC... 00Z HREF guidance supports scattered to numerous thunderstorms this afternoon with transient organizational structures that should be sufficient for a scattered damaging wind threat. This appears to be largely in response to the eastward progression of an MCV currently near the IN/OH/KY border. A compact belt of enhanced mid-level westerlies should overspread the northern periphery of ample MLCAPE emanating from the South Atlantic Coastal Plain. Multicell clusters that can progress towards a warmer/deeper boundary layer across the Piedmont and Coastal Plain should produce strong to sporadic severe gusts through early evening. ...Grams/Wendt.. 07/18/2025 $$ = = = 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) .