Subj : DAY1SVR: Day 1 Convective Outlook To : wx-storm@lists.illinois.edu From : COD Weather Processor Date : Thu Aug 31 2023 19:44:54 ACUS01 KWNS 311944 SWODY1 SPC AC 311943 Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0243 PM CDT Thu Aug 31 2023 Valid 312000Z - 011200Z ....THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS LATE THIS AFTERNOON AND EVENING ACROSS PARTS OF SOUTH CENTRAL THROUGH NORTHWESTERN ARIZONA...AND ADJACENT PORTIONS OF SOUTHEASTERN CALIFORNIA...SOUTHERN NEVADA AND SOUTHWESTERN UTAH... ....SUMMARY... Widely scattered thunderstorms with a few strong wind gusts are possible across Arizona and the Lower Colorado River Valley late this afternoon into evening. ....20Z Update... No changes were made to the severe probabilities, but there are some adjustments to the categorical (10 percent probability) thunder line to account for the progression of synoptic features, and current trends concerning destabilization. Particularly east of the Colorado Rockies into the northern Great Plains Red River Valley/Upper Midwest, stronger mid/upper support for convective development has shifted into the eastern Canadian Prairies, downstream of the significant mid-level low/troughing migrating north of the international border vicinity. A plume of rather modest moisture does exist ahead of associated lee surface troughing, extending south-southwestward across the eastern Dakotas toward the Raton Mesa vicinity. However, warm/dry layers in the lower/mid troposphere seem likely to suppress an appreciable risk for sustained thunderstorm development across much of this region. ...Kerr.. 08/31/2023 ..PREV DISCUSSION... /ISSUED 1124 AM CDT Thu Aug 31 2023/ ....AZ/lower CO River Valley this afternoon through tonight... A midlevel high over NM this morning will shift east-northeastward toward the southern/central High Plains as an upstream shortwave trough evolves into a closed low over western OR and northern CA. A plume of 1.25-1.50 inch PW will be drawn northward from southwest AZ toward southeast NV and southwest UT through tonight around the northwest periphery of the NM high, as height gradients/flow gradually strengthen between the high and the developing Pacific coast low. This will result in some destabilization (when combined with daytime heating and deep mixing) and the potential for scattered high-based thunderstorms this afternoon into tonight from southern AZ into extreme southeast CA, southeast NV and extreme southwest UT. Thunderstorms are expected to develop over the Mogollon Rim and the higher terrain in southeast AZ, and subsequently spread westward/northwestward on convective outflows. MLCAPE up to 1000 J/kg with deep inverted-V profiles will support strong/isolated severe outflow gusts from later this afternoon into early tonight as thunderstorm clusters spread across AZ toward southeast NV/southwest UT. $$ = = = 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) .