Subj : DAY1SVR: Day 1 Convective Outlook To : wx-storm@lists.illinois.edu From : COD Weather Processor Date : Mon Aug 25 2025 16:32:37 ACUS01 KWNS 251632 SWODY1 SPC AC 251631 Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 1131 AM CDT Mon Aug 25 2025 Valid 251630Z - 261200Z ....THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS SOUTHERN ARIZONA... ....SUMMARY... Isolated severe wind gusts are possible over parts of south-central Arizona this afternoon through early evening. Otherwise, the potential for severe storms is low across the remainder of the continental U.S. ....Synopsis... A large upper trough will remain over the eastern CONUS today, as several embedded shortwave troughs progress within its southern periphery. Extensive upper ridging that currently extends from the southern Plains into the northern Intermountain West is forecast to remain largely in place. Some dampening may occur along the northwestern periphery of this ridging as a slow-moving vorticity maximum continues northeastward from the CO/OR/NV border vicinity into more of eastern OR. Ample monsoonal moisture exists beneath this ridging, contributing to scattered to numerous thunderstorms from the southern/central Rockies westward across the Southwest and much of the Great Basin. Limited vertical shear and weak buoyancy will mitigate the severe potential across the majority of the region. The only exceptions are across central Rockies and immediate foothills, and portions of southern AZ. ....Southern AZ... Ample monsoonal moisture is in place across the region, evidenced by PW values of 1.66 and 1.83 inches from the Phoenix and Yuma 12Z soundings, respectively. Filtered diurnal heating within this moist airmass will support modest buoyancy and afternoon thunderstorm development. A belt of stronger mid-level southeasterly flow (20-25 kt) is forecast to overspread the region this afternoon, providing ample shear for some multicell storm clusters. Initial storms which are expected to form across the higher terrain in southeast Arizona may result in congealing outflow with a damaging wind threat as storms move generally west-northwestward through the evening. ....Central Rockies... Thunderstorm development is expected across the high terrain by the early afternoon. Poor lapse rates and cooler temperatures will keep buoyancy will be modest, likely limiting overall updraft strength and tempering the severe potential. Even so, moderate northwesterly flow aloft will support long hodographs and the potential for some storm organization if updrafts can become sufficiently deep. An instance or two of hail is possible with any stronger, more long-lived storms. ...Mosier/Moore.. 08/25/2025 $$ = = = 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) .