Subj : DAY1SVR: Day 1 Convective Outlook To : wx-storm@lists.illinois.edu From : COD Weather Processor Date : Fri Aug 18 2023 16:30:48 ACUS01 KWNS 181630 SWODY1 SPC AC 181629 Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 1129 AM CDT Fri Aug 18 2023 Valid 181630Z - 191200Z ....THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS PARTS OF THE DESERT SOUTHWEST...MT...AND NEW ENGLAND... ....SUMMARY... Isolated strong to severe wind gusts are possible, mainly from late afternoon to mid-evening across parts of Montana, the Desert Southwest, and New England. ....MT... Despite lingering mid-level clouds tempering insolation to some extent, surface temperatures should still heat into the 90s across eastern MT by late afternoon. Large-scale ascent attendant to a shortwave trough tracking east from southern BC to the lee of the Canadian Rockies should largely hold north of the international border. But low-level speed convergence should increase this evening along a trailing surface cold front and this may aid in sustaining isolated thunderstorms off the higher terrain of southwest MT. While MLCAPE should remain meager (at or below 500 J/kg), very deeply mixed profiles east of the terrain will support a threat for isolated severe wind gusts. ....Desert Southwest.... Weak deep-layer shear will be the primary limiting factor to a more organized severe wind threat, with mainly 15-25 kt 500-mb southerlies between a stout anticyclone over the southern Great Plains and a cutoff low off the southern CA coast. Scattered thunderstorms developing over the higher terrain, aided by a high PW air mass emanating north from the Gulf of CA, will pose a threat for sporadic severe wind gusts as they spread/collide northward within the deeply mixed environment across the lower deserts. ....New England... In the wake of this morning's tornadic supercell, low-level winds have substantially veered and weakened ahead of a north to south-oriented cold front pushing east into western New England. With a wedge of greater insolation between it and cloud cover associated with the early-day convection that is now largely off the coast, MLCAPE of 500-1000 J/kg should redevelop over the next few hours and support deepening convection along the front. While adequate deep-layer shear will remain, the increasingly poor low-level wind fields should mitigate an organized damaging wind threat. Still, a few strong gusts remain possible until the front reaches the coast. ...Grams/Moore.. 08/18/2023 $$ = = = 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 3.14-Linux * Origin: capitolcityonline.net * Telnet/SSH:2022/HTTP (1:2320/105) .