Subj : DAY1SVR: Day 1 Convective Outlook To : wx-storm@lists.illinois.edu From : COD Weather Processor Date : Fri Sep 12 2025 05:34:53 ACUS01 KWNS 120534 SWODY1 SPC AC 120533 Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 1233 AM CDT Fri Sep 12 2025 Valid 121200Z - 131200Z ....THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS FROM EASTERN MONTANA INTO THE DAKOTAS AND ACROSS THE FOUR CORNERS REGION... ....SUMMARY... A few storms capable of isolated severe wind gusts are possible across the Four Corners region, and from eastern Montana into the Dakotas. ....Synopsis... An upper trough will remain over the Intermountain West, making slow eastward progress through the period. An upper disturbance is forecast to move from CO into the Dakotas late in the day, while a strong midlevel jet rounds the base of the trough across AZ overnight. Gradual height falls will occur across the length of High Plains primary overnight as the Plains upper ridge gradually weakens. At the surface, a weak area of low pressure is forecast over SD, with a trough extending westward across WY and into the Great Basin during the afternoon with strong heating. Dewpoints in the 60s F will be common across the mid MO Valley, especially from MN into the Dakotas where surface winds will be backed north of the low. Rather veered/southwesterly 850 mb flow is forecast overnight, with only pockets of positive theta-e advection. ....Eastern MT into the Dakotas... Moderate instability will develop over much of the northern Plains, but beneath temporary upper ridging. Storms are most likely to form over eastern MT and WY, beneath cooler temperatures aloft and where less capping will exist. Isolated hail may occur with these widely scattered afternoon cells. Later in the evening, a few cells may persist into the western Dakotas with hail potential, and there appears to be a possibility of scattered damaging gusts as activity/outflow moves out of WY/CO and interacts with stronger instability over the Dakotas overnight. Given the lack of low-level jet support and uncertainty, will maintain 5% probabilities. ....Four Corners Region... Daytime heating combined with a midlevel moist plume and cooling aloft should yield scattered afternoon development over far eastern AZ and UT into western CO and NM. Instability will not be particularly strong, but likely sufficient for a few damaging gusts or marginal hail as the most prevalent storm mode is expected to be cellular with favorably long hodographs/veering with height. Some of this activity may persist well into the evening over NM. ...Jewell/Squitieri.. 09/12/2025 $$ = = = 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) .