Subj : DAY1SVR: Day 1 Convective Outlook To : wx-storm@lists.illinois.edu From : COD Weather Processor Date : Tue Sep 16 2025 16:39:53 ACUS01 KWNS 161639 SWODY1 SPC AC 161638 Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 1138 AM CDT Tue Sep 16 2025 Valid 161630Z - 171200Z ....THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS THE CENTRAL HIGH PLAINS... ....SUMMARY... Scattered severe thunderstorms are expected this afternoon into early evening across a portion of the central Great Plains. Large hail, severe gusts, and a tornado or two may occur. ....Eastern Colorado/Wyoming and Central Plains... A semi-closed upper low will continue to spread southeastward today over Wyoming and nearby parts of southern Montana and northern Colorado, as a cold front similarly settles southeastward across the Front Range/central High Plains, while a weak surface wave develops northeastward along the front. Increasing forcing for ascent/strengthening flow aloft related to a lead portion of the upper trough will influence steadily increasing and organized thunderstorm development into the afternoon, especially within the immediate post-frontal environment. Buoyancy will be maximized from far northeast Colorado into central Nebraska where low to mid 60s F dewpoints beneath steep mid-level lapse rates will support MLCAPE around 2000-2500 J/kg. The resulting combination of lift, instability, and moderate shear (generally around 35 kt of effective bulk shear) will support strong to severe storms. Large hail appears to be the most prominent hazard (especially western Nebraska), but some clustering could lead to a few strong gusts as well. Presence of the surface low/boundary and backed low-level flow may result in a low-probability tornado risk as well. ....Iowa/northern Missouri/eastern Nebraska... Some stronger/locally severe pulse-type storms may occur late this afternoon through around sunset within the strong instability/weak deep-layer flow regime. ....Northern Minnesota/Lake Superior... Severe-weather potential should be limited across this region, but will retain low-severe probabilities given somewhat stronger deep-layer shear and a low or conditional-type potential near the advancing front. ....Virginia Tidewater/far northeast North Carolina... Surface reflection of a semi-stacked cyclone is just off the far northeast corner of North Carolina at midday. This low should continue to drift north-northwest today and tonight, while likely gradually weakening, although its northern peripheral strong low-level east/northeasterly winds (reference Wakefield WSR-88D VWP) will likely persist through the day. Dry northerly continental trajectories inland will relegate meaningful (albeit limited) buoyancy to the immediate coasts of the Virginia Tidewater/Maryland shore, and otherwise offshore. This will similarly relegate any transient supercell and low-end tornado/wind risk to the immediate coast, but more likely just offshore. ...Guyer/Thornton.. 09/16/2025 $$ = = = 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) .