Subj : DAY1SVR: Day 1 Convective To : All From : Mike Powell Date : Tue Sep 03 2024 08:38:00 ACUS01 KWNS 031235 SWODY1 SPC AC 031234 Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0734 AM CDT Tue Sep 03 2024 Valid 031300Z - 041200Z ....THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF THE NORTHERN ROCKIES/GREAT BASIN AND ADJACENT HIGH PLAINS... ....SUMMARY... Thunderstorms developing across the northern Rockies and adjacent portions of the Great Basin this afternoon may produce occasional strong to severe wind gusts, before spreading eastward toward the northern High Plains this evening. ....Northern Great Basin/Rockies into the Adjacent High Plains... An upper trough/low over the Pacific Northwest this morning will continue moving eastward today across the northern Rockies. This feature is forecast to gradually weaken through the period, but enhanced mid-level west-southwesterly flow will persist across parts of the northern Great Basin into the northern Rockies and adjacent High Plains. As large-scale ascent associated with the upper trough overspreads the northern Rockies, thunderstorms should develop over the higher terrain through early afternoon in tandem with daytime heating. Latest surface observations show somewhat greater low-level moisture across this region, with surface dewpoints generally in the mid 40s to low 50s across central ID into southwest MT. Although instability is forecast to remain fairly modest this afternoon, deep-layer shear around 25-35 kt should be sufficient to support organized convection, including the potential for a couple of marginal supercells initially with associated hail/wind threat. With steepened low/mid-level lapse rates present, this activity should continue to pose some threat for isolated strong to severe wind gusts as it congeals and spreads east-northeastward across parts of the northern High Plains through this evening. Somewhat more limited low-level moisture should be present this afternoon farther south into WY and northern UT. Even so, diurnal heating will aid in a deeply mixed boundary layer by this afternoon, and steep mid-level lapse rates are also expected to remain over this region. The net result will be high-based thunderstorms capable of producing isolated strong to severe winds initially developing across northern UT into far eastern ID, and subsequently moving east-northeastward over WY through the evening. Confidence in a more concentrated corridor of severe winds remains generally low at this time given the weak instability and modest deep-layer shear forecast, especially with southward extent into the northern Great Basin and WY. ...Gleason/Leitman.. 09/03/2024 $$ --- SBBSecho 3.20-Linux * Origin: ILink: CCO - capitolcityonline.net (454:3/105) .