Subj : DAY2SVR: Nws Storm Prediction Center Norman Ok To : wx-storm@lists.illinois.edu From : COD Weather Processor Date : Sun Jul 30 2023 17:32:08 ACUS02 KWNS 301732 SWODY2 SPC AC 301730 Day 2 Convective Outlook NWS Storm Prediction Center Norman OK 1230 PM CDT Sun Jul 30 2023 Valid 311200Z - 011200Z ....THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF THE NORTHERN/CENTRAL PLAINS...LOWER/MID MISSISSIPPI VALLEY...COASTAL SOUTHEAST...AND SOUTHERN ARIZONA... ....SUMMARY... Isolated strong to severe thunderstorms capable of producing large hail and gusty winds appear possible Monday across parts of the northern/central Plains. Additional thunderstorms producing mainly strong to damaging winds may occur across parts of the lower/mid Mississippi Valley, coastal Southeast, and southern Arizona. ....Synopsis... An upper-level anticyclone will remain centered over the southern Plains Monday, with upper ridging extending northward over much of the Rockies and High Plains. Upper troughing will persist over much of eastern Canada and the Atlantic Coast states. A belt of enhanced mid-level northwesterly flow is forecast to persist from the northern Plains across the Midwest/OH Valley and parts of the Southeast. Surface high pressure will dominate over much of these regions as well, with a weak front forecast to be located along/near the central Gulf Coast northeastward to southeastern VA. Across the Plains, a surface trough should extend from eastern MT into eastern CO, with a reservoir of rich low-level moisture present to its east. ....Northern/Central Plains... Thunderstorms should form Monday afternoon over the higher terrain of the northern/central Rockies, and eventually develop eastward over the adjacent northern/central High Plains. One or more subtle mid-level vorticity maxima rotating around the upper ridge may aid this convective development. Greater low-level moisture and related instability is forecast to be present along/east of a weak surface trough across the High Plains. There will be some potential for initially high-based convection to gradually strengthen with eastward extent through Monday evening/night. Forecast deep-layer shear would support a mix of multicells and supercells with an associated threat for large hail and severe/damaging winds. However, considerable uncertainty remains regarding the number of supercells which may develop given weak/nebulous forcing aloft. Have therefore expanded the Marginal Risk to account for a range of possible solutions regarding convective evolution. ....Lower/Mid Mississippi Valley... Thunderstorms may be ongoing Monday morning across parts of MO and vicinity. This activity should be related to convection that is expected to develop during the Day 1 period across the northern/central High Plains, and subsequently spread southeastward overnight into early Monday morning. Modest low-level warm advection may also aid thunderstorm maintenance Monday morning. While details regarding convective evolution remain somewhat unclear, most guidance has come into general agreement that a small cluster will persist through the day as it moves south-southeastward across the lower/mid MS Valley. Moderate to strong instability should be in place ahead of this convection as daytime heating of a moist low-level airmass occurs. Although deep-layer shear should remain fairly modest, enough convective organization appears possible to support a cluster capable of producing mainly damaging winds through early Monday evening. ....Coastal Southeast... A rather moist low-level airmass should be in place ahead of a weak front across parts of the coastal Southeast states. Even though mid-level lapse rates will remain fairly poor, diurnal heating of this moist airmass will aid destabilization and steepening of low-level lapse rates by Monday afternoon. Thunderstorms that form across this region through the day may produce isolated damaging winds, with modest deep-layer shear aiding a mix of pulse and loosely organized multicell modes. This convection should diminish/move offshore Monday evening with the loss of daytime heating. ....Southern Arizona... Monsoonal moisture will likely remain across southern AZ on Monday. Convection should once again develop across the higher terrain of southeastern AZ during the afternoon. Modest easterly mid/upper-level flow should aid thunderstorms spreading eastward over the lower deserts through Monday evening. Isolated strong to severe wind gusts may occur with this activity, as very steep low/mid-level lapse rates aid efficient downdraft accelerations. ...Gleason.. 07/30/2023 $$ = = = 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) .