Subj : DAY1SVR: Day 1 Convective Outlook To : wx-storm@lists.illinois.edu From : COD Weather Processor Date : Mon Aug 04 2025 16:37:39 ACUS01 KWNS 041637 SWODY1 SPC AC 041636 Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 1136 AM CDT Mon Aug 04 2025 Valid 041630Z - 051200Z ....THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PORTIONS OF THE HIGH PLAINS... ....SUMMARY... Thunderstorms with severe gusts and large to very large hail will be possible this afternoon through this evening from parts of the northern Rockies into the Dakotas and central/southern High Plains. ....Central High Plains... An upper ridge extending from NM north-northeastward into the central High Plains will feature a couple of weak disturbances cresting the ridge through early Tuesday morning. The most notable disturbance over northeast UT late this morning is forecast to move east across southern WY by early evening and potentially play a role in storm development late this afternoon/evening. A seasonably moist airmass featuring 55-60 deg F dewpoints into eastern WY/NE Panhandle will undergo strong heating. Low-level southeasterly flow will veer to northwesterly in the mid levels, resulting in moderate to strong deep-layer vertical shear and an overall wind profile that favors supercells. As such, there is conditional risk for severe thunderstorms. However, the forcing mechanism for convective initiation is fairly weak. The general expectation is that low-level convergence and upslope flow across the Black Hills vicinity should be enough for scattered convective initiation with other widely scattered storms possible farther south. The environment supports supercells capable of large to very large hail and severe gusts. Any supercells that develop could last for a few hours, but should eventually trend towards a more linear mode with one or more clusters evolving across western/central NE and northeast CO this evening. Aided by a 40+ kt low-level jet, continued upscale growth should support these clusters of strong to severe storms into the overnight hours where damaging winds will be possible. ....Northern Rockies into eastern Montana... Water-vapor imagery shows a potent mid- to upper-level shortwave trough moving east across OR this morning. This disturbance is forecast to move into the northern Rockies by early evening and into the northern High Plains by daybreak. Strong large-scale ascent associated with this shortwave trough as it acquires a negative tilt, will favor isolated to scattered storms from the Snake Valley northward into north-central ID and into western/southwest MT. Initially cellular storms will pose an isolated risk for severe wind gusts. As storms move into the high plains, slightly greater low-level moisture will aid in more numerous storms developing and their attendant outflow. Scattered severe gusts (60-75 mph) are possible with this activity as it moves east-northeast across MT. ....Southern High Plains... Strong heating along a lee trough could support isolated to widely scattered thunderstorm development from the Raton Mesa into southeast CO/northeast NM. Ample high-level flow atop strongly veering low-level winds, coupled with a very unstable airmass on the western periphery of rich moisture, will favor the possibility for a few supercells by late afternoon. Large to very large hail, severe gusts, and a brief tornado are the potential hazards. Some guidance shows a cluster evolving during the evening with severe gusts becoming the primary hazard. ....Central/Southeast Texas... A weakening squall line will continue southward to the middle TX coast over the next couple of hours with other weak thunderstorm activity perhaps lingering atop the cold pool. Isolated strong gusts will probably become increasingly localized during the midday. ...Smith/Wendt.. 08/04/2025 $$ = = = 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) .