Subj : DAY2SVR: Nws Storm Prediction Center Norman Ok To : wx-storm@lists.illinois.edu From : COD Weather Processor Date : Fri Jul 21 2023 17:32:19 ACUS02 KWNS 211732 SWODY2 SPC AC 211730 Day 2 Convective Outlook NWS Storm Prediction Center Norman OK 1230 PM CDT Fri Jul 21 2023 Valid 221200Z - 231200Z ....THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF THE CENTRAL PLAINS INTO THE UPPER MIDWEST...SOUTHEAST...AND ARIZONA... ....SUMMARY... Widely scattered strong to severe thunderstorms appear possible on Saturday across parts of the central Plains into the Upper Midwest, Southeast, and Arizona. ....Synopsis... An upper ridge will remain centered over much of the western CONUS Saturday, while broad upper troughing encompasses the central and eastern states. Modestly enhanced west-northwesterly mid-level flow should be present between these two features. Greater low-level moisture should remain confined to parts of the Southeast along and south of a convectively reinforced front. But, sufficient moisture across the central Plains and Upper Midwest should be in place to support at least isolated robust convection. ....Central Plains/Upper Midwest... Around 30-40 kt of northwesterly mid-level flow will remain over much of the central Plains into the Upper Midwest on Saturday. While low-level moisture may remain fairly shallow/limited by late July standards, steepened low/mid-level lapse rates and daytime heating should promote the development of weak to moderate instability by late Saturday afternoon. Large-scale ascent appears nebulous, but isolated to scattered convection may still develop along and southeast of a weak surface trough. With 25-40 kt of deep-layer shear forecast, a widely spaced mix of multicells and supercells may develop and spread southeastward through Saturday evening while posing an isolated threat for large hail and severe wind gusts. Based on latest guidance, have expanded the Marginal Risk to encompass more of the central Plains and Upper Midwest. ....Southeast... Scattered showers and thunderstorms may be ongoing Saturday morning across parts of MS/AL into GA and perhaps SC. The convectively reinforced outflow/front and a separate sea breeze will likely be foci for renewed convective development by Saturday afternoon. A belt of modest westerly mid-level winds at the base of the large-scale upper trough will exist across much of the Southeast. Plentiful low-level moisture, with surface dewpoints generally in the 70s, and ample diurnal heating will likely foster moderate to strong instability by early Saturday afternoon. Scattered to numerous thunderstorms should develop in this environment along and south of the front. Strong to locally damaging winds may occur with the more robust convection given the very moist profiles, and some clustering may occur. Isolated hail also appears possible with the strongest cores. At this point, not enough confidence exists to include greater severe wind probabilities. But, have expanded the Marginal Risk to include more of the Gulf Coast into north FL. ....Arizona... An upper-level anticyclone will remain centered near the Four Corners region Saturday. It appears that modest (15-20 kt) east-northeasterly mid-level winds will be present across parts of southern AZ and vicinity. As thunderstorms develop over the higher terrain, there may be enough low/mid-level flow to push this convection westward into the lower terrain of southern/central AZ. Very steep low/mid-level lapse rates with a well-mixed boundary layer and ample DCAPE should support some threat for severe winds if this occurs. With a better signal of this potential in recent high-resolution guidance, have added a Marginal Risk for severe/damaging winds. ...Gleason.. 07/21/2023 $$ = = = 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) .