Subj : DAY2SVR: Nws Storm Prediction Center Norman Ok To : wx-storm@lists.illinois.edu From : COD Weather Processor Date : Sat Jul 29 2023 05:41:25 ACUS02 KWNS 290541 SWODY2 SPC AC 290539 Day 2 Convective Outlook NWS Storm Prediction Center Norman OK 1239 AM CDT Sat Jul 29 2023 Valid 301200Z - 311200Z ....THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS PORTIONS OF THE NORTHERN AND CENTRAL HIGH PLAINS...AND ACROSS THE MID-SOUTH VICINITY... ....SUMMARY... Isolated severe thunderstorms are possible Sunday from the Missouri Ozarks into the Tennessee Valley, as well as over the northern and central High Plains. ....Synopsis... An amplified upper ridge will be centered over the High Plains vicinity on Sunday. Meanwhile, an upper trough will encompass portions of the eastern U.S. A band of weak to moderate mid/upper northwesterly flow between these two features will extend from the northern/central Plains toward the TN Valley vicinity. A weak surface front draped from the Mid-MO Valley region toward Middle TN during the afternoon will drift southward through the period. Meanwhile, a surface trough will extend southward across the northern/central High Plains. Southeasterly low-level flow to the east of the surface trough will support a moistening boundary layer. Thunderstorms are expected to develop in the vicinity of the High Plains surface trough, and the Mid-South/Southern States front. ....Northern/Central Plains vicinity... Isolated to widely scattered thunderstorms are expected to develop by late afternoon near higher terrain within the vicinity of a surface trough. East/southeasterly low-level flow will maintain a plume of 60s F boundary-layer dewpoints, aiding in weak to moderate destabilization. While this low-level warm advection and modest ascent associated with weak vorticity maxima rotating through the upper ridge provide support for thunderstorm development, capping may limit coverage/longevity of stronger organized updrafts. Any sustained convection will pose a risk for hail, as vertically veering wind profiles lead to elongated hodographs amid steep midlevel lapse rates. Sporadic strong to severe gusts also will be possible. If sufficient clustering occurs, some guidance suggests a forward propagating cluster could develop and shift southeast across parts of eastern WY/southwest SD/western NE during the evening. If this occurs, some greater potential for damaging gusts may develop, though confidence in this scenario is currently low. ....Ozarks to Mid-South vicinity... A good amount of uncertainty continues regarding severe potential on Sunday. Forecast guidance is quite varied in the location of the surface front, whether or not convection will be ongoing Sunday morning, and how far south and east severe potential may develop. As a result, only minor modifications have been made to the Marginal risk (level 1 of 5) from the prior Day 3 outlook. Depending on model trends, and convective trends in the Day 1/Saturday time frame, this area may need to be adjusted and/or removed in subsequent outlooks. While uncertainty is high, a seasonally moist and unstable airmass will reside over the region. If storms develop near the surface front, at least modest deep-layer northwesterly flow will support strong thunderstorm clusters. Adequate instability and steep low-level lapse rates will foster locally damaging gust potential with any better organized/propagating clusters that develop. ...Leitman.. 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) .