Subj : DAY2SVR: Nws Storm Prediction Center Norman Ok To : wx-storm@lists.illinois.edu From : COD Weather Processor Date : Sat Jul 29 2023 17:32:31 ACUS02 KWNS 291732 SWODY2 SPC AC 291730 Day 2 Convective Outlook NWS Storm Prediction Center Norman OK 1230 PM CDT Sat Jul 29 2023 Valid 301200Z - 311200Z ....THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF THE NORTHERN/CENTRAL HIGH PLAINS...MID MISSOURI VALLEY INTO THE TENNESSEE VALLEY AND SOUTHEAST...AND ARIZONA... ....SUMMARY... Isolated strong to severe thunderstorms appear possible Sunday from parts of the mid Missouri Valley into the Tennessee Valley and Southeast, as well portions of the northern/central High Plains, and Arizona. ....Synopsis... An expansive upper ridge/anticyclone will remain centered over much of the Southwest and southern Plains on Sunday. Multiple low-amplitude, mid-level perturbations are forecast to advance around the crest of this upper ridge across the northern Rockies and adjacent High Plains through the period. Large-scale upper troughing will be maintained over a majority of the eastern states and Canada. A belt of enhanced mid-level northwesterly winds should persist between the upper ridge/trough over portions of the Upper Midwest, OH/TN Valleys, and eastern CONUS. At the surface, weak lee troughing should exist across parts of the northern/central High Plains. Farther east, an ill-defined and convectively reinforced front should extend from parts of the Mid-Atlantic westward into the TN Valley and Mid-South. ....Northern/Central High Plains... At least isolated thunderstorms should develop by mid Sunday afternoon across the higher terrain of the northern/central Rockies. This activity is forecast to develop generally eastward into the adjacent northern/central High Plains with time. As this convection encounters greater low-level moisture and instability along/east of the weak lee trough, it should gradually strengthen. Various NAM/RAP forecast soundings across eastern MT/WY into the Dakotas and western NE depict favorable deep-layer shear that would support supercells. An isolated threat for large hail and severe wind gusts would accompany this activity as it moves eastward through Sunday evening/night, as steep mid-level lapse rates aid robust updrafts and hail production. At this point, confidence in a more concentrated corridor of severe potential remains low, as large-scale ascent associated with weak mid-level impulses rounding the upper ridge appears somewhat nebulous. ....Mid Missouri Valley into the Tennessee Valley and Southeast... Convective evolution remains uncertain across these regions on Sunday. Thunderstorms may once again be ongoing at the start of the period across parts of the Mid MO Valley and vicinity, in association with earlier/overnight convection across the central Plains. An isolated wind threat could persist with this activity Sunday morning into afternoon as it spreads southeastward across MO into the Mid-South and TN Valley with a destabilizing airmass along/south of a weak front. A convectively generated MCV related to convection ongoing in the Day 1 period across MO will probably be located somewhere across the TN Valley and southern Appalachians by Sunday morning. Renewed convective development across GA into SC should occur by Sunday afternoon along/east of this MCV and related weak mid-level perturbation. Although deep-layer shear is forecast to remain weak, a mix of pulse and loosely organized multicells appear possible. Steepening low-level lapse rates and destabilization of a moist boundary layer should promote some threat for damaging winds with the strongest cores. Other convection also appears likely to develop across the Deep South/central Gulf Coast vicinity, with some of this activity related to various sea breezes. Based on consensus of latest guidance showing at least scattered thunderstorms developing across much of this area, have expanded the Marginal Risk for damaging winds to include more of the Southeast. ....Arizona... Thunderstorms that develop over the higher terrain of the Rim and southeastern AZ should be able to move into the lower deserts late Sunday afternoon through Sunday evening, as easterly mid-level flow around 15-25 kt on the southern periphery of the upper ridge/anticyclone should aid westward propagation. Very steep low/mid-level lapse rates associated with a hot and well-mixed boundary layer may prove favorable for convective downdrafts occasionally producing severe wind gusts. ...Gleason.. 07/29/2023 $$ = = = 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) .