Subj : DAY3SVR: Nws Storm Prediction Center Norman Ok To : wx-storm@lists.illinois.edu From : COD Weather Processor Date : Sat Sep 30 2023 07:31:16 ACUS03 KWNS 300731 SWODY3 SPC AC 300730 Day 3 Convective Outlook NWS Storm Prediction Center Norman OK 0230 AM CDT Sat Sep 30 2023 Valid 021200Z - 031200Z ....THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS OVER THE NORTHERN PLAINS AND SOUTHERN HIGH PLAINS... ....SUMMARY... Scattered severe storms will be possible Monday over the northern Plains, and over parts of the southern High Plains. Hail and damaging gusts will be the primary risks. ....Synopsis... An amplified upper-air pattern will persist on Monday, with an upper trough moving across the Rockies and an expansive ridge over the eastern CONUS. The upper trough will make relatively slow eastward progress through the period, resulting in gradual height falls across the length of the High Plains. The strongest speed max within the southwest flow regime preceding the trough will exist over the Four Corners area early in the day, but overall it appears the midlevel gradients will weaken somewhat with time. However, embedded disturbances will be possible across the region. At the surface, high pressure will encompass much of the eastern CONUS, with a weak surface trough over the High Plains enhancing convergence. Low-level moisture will not be particularly robust given the trajectories out of the high, but pockets of instability will develop due to heating and generally mid to upper 50s F dewpoints across the warm sector. ....Northern Plains... A stalled front is forecast to stretch roughly from northeast WY/southeast MT across the central Dakotas during the day. Low pressure is forecast to develop over southeast WY during the afternoon, and translate northeastward along the surface trough and into eastern ND by 12Z Tuesday. An uncapped air mass, steepening lapse rates and elongated hodographs especially in the mid to upper levels will favor storms producing large hail, likely forming over eastern WY late in the day and continuing overnight into the Dakotas. A narrow corridor of greater than 5% severe coverage may eventually develop for hail or wind risk along the boundary, and adjustments may be made as predictability increases. ....Southern High Plains... MUCAPE on the order of 1000 J/kg along with 40 kt deep-layer shear is forecast to develop over eastern NM, southeast CO and western TX as the upper trough approaches. Southeasterly low-level flow will bring moisture northwestward at increasing elevations, and heating will result in an uncapped air mass with scattered afternoon thunderstorms. Veering winds with height will favor cellular storm mode, with hail around 1.00" likely. Clusters of storms may persist overnight, eventually moving into western TX. ...Jewell.. 09/30/2023 $$ = = = 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) .