Subj : DAY1SVR: Day 1 Convective Outlook To : wx-storm@lists.illinois.edu From : COD Weather Processor Date : Mon Jun 30 2025 12:51:24 ACUS01 KWNS 301250 SWODY1 SPC AC 301248 Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0748 AM CDT Mon Jun 30 2025 Valid 301300Z - 011200Z ....THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS THE SOUTHERN PLAINS INTO THE MIDWEST AND MID ATLANTIC STATES...AND PARTS OF THE DESERT SOUTHWEST AND WEST COAST... ....SUMMARY... Isolated severe thunderstorms are possible across portions of the southern Plains into the Midwest and the Mid-Atlantic, and in parts of the Desert Southwest, and also in adjacent parts of southern Oregon and northern California today. ....Synopsis... Water-vapor imagery this morning shows an upper trough over the Dakotas/Upper Midwest, and this feature is forecast to move into the Great Lakes by tonight. At the same time, sub-tropical ridging will build over the Plains, keeping stronger flow aloft displaced to the north. Farther west, an upper trough/low will meander slowly eastward over the eastern Pacific towards the CA coast. At the surface, a weak cold front will sag southward from the Midwest to the southern Plains. ....Southern Plains into the Midwest and Mid-Atlantic states... A myriad of prior convective outflow in addition to the cold front will serve as foci for storm development today. Ahead of the slow-moving cold front, rich low-level moisture and heating will lead to moderate to strong destabilization in areas void of persistent early day cloud debris. Small clusters and bands of storms may locally concentrate some damaging-wind threat, but predictability of these meso-beta corridors remains uncertain. Nonetheless, scattered storms will gradually progress east and southward during the day and through the evening across the Marginal Risk area. Strong to severe downdrafts will be the primary severe threat, but large hail may occur with a few storms over parts of the southern Plains where lapse rates/buoyancy are greater than areas farther northeast. The overall severe threat will likely remain tempered by weak to modest mid-level flow. ....Southwest NM and far southeast AZ... Strong heating of an adequately moist airmass will result in appreciable buoyancy by peak heating. Scattered thunderstorms developing within an environment characterized by very steep lapse rates and inverted-v profiles, will support isolated severe gusts (60-70 mph) with the stronger evaporatively cooled downdrafts during the late afternoon and early evening. ....Northern CA into southern OR... Ahead of the weak upper trough immediately west of the CA coast, southerly flow will aid in increasing mid-level moisture across parts of northern CA and southern OR. Ample heating coupled with weak large-scale and orographic ascent will aid in isolated to scattered high-based thunderstorm development. Very steep lapse rates and a deep, dry sub cloud layer will favor evaporatively cooled downdrafts capable of isolated 55-65 mph gusts. ...Smith/Broyles.. 06/30/2025 $$ = = = 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 3.20-Linux * Origin: capitolcityonline.net * Telnet/SSH:2022/HTTP (1:2320/105) .