Subj : DAY1SVR: Day 1 Convective Outlook To : wx-storm@lists.illinois.edu From : COD Weather Processor Date : Fri Nov 25 2022 12:56:09 ACUS01 KWNS 251256 SWODY1 SPC AC 251254 Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0654 AM CST Fri Nov 25 2022 Valid 251300Z - 261200Z ....THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS NEAR PARTS OF THE TEXAS COAST... ....SUMMARY... Isolated strong to severe thunderstorms may occur tonight near parts of the Texas Coast. ....Synopsis... In mid/upper levels, a split-flow pattern prevails over the central CONUS, related to a synoptic-scale, southern-stream cyclone now centered near ELP. Meanwhile, a positively tilted, northern-stream shortwave trough is apparent in moisture-channel imagery over the northeastern Pacific, extending from just northwest of Vancouver Island southwestward. This perturbation will move southeastward to the northern Rockies, southwestern ID and northern CA by 12Z tomorrow. As that occurs, the southern-stream cyclone will meander southward over northern Chihuahua today, then start ejecting northeastward over the Big Bend and lower Pecos Valley regions overnight. By 12Z, the 50-mb low should be located in the FST/MAF area, with the strongest deep-tropospheric (850-250 mb) flow over south and central TX, in the cyclone's southeastern and eastern sectors. At the surface, 11Z analysis showed a wavy, quasistationary frontal zone from coastal NC southwestward over northwestern FL, then westward over the central parts of the FL Panhandle, to near the Mississippi River mouth, and across the northwestern Gulf just off the TX Coast. As the mid/upper cyclone pivots over west TX this evening through tonight, a surface low should form along the front over coastal deep south TX, then accelerate north-northeastward over the lower/middle TX Coast, then inland across southeast TX to near CLL by 12Z. This low's inland progress should outrun that of the most favorable Gulf air mass overnight. ....TX Coast... Scattered thunderstorms are expected to move northward to northeastward over central and coastal south TX this evening into tonight. Activity very near the coast may offer a damaging gust or brief, conditional overland tornado threat. The strongest DCVA should lag behind the low and trailing cold front. This will contribute to extensive precip and episodic, elevated thunderstorms over the surface cold sector, in an extensive warm-advection conveyor wrapping northwestward from coastal regions. Amid weak CINH, strengthening/difluent upper winds and height falls aloft, the seaward part of the warm-advection/moisture-transport plume also will support increasing thunderstorm potential near the coast from late afternoon onward. Largest low-level theta-e will remain over Gulf waters, where MLCAPE should exceed 1000 J/kg, and the greatest favorable buoyancy/shear parameter space for supercells is expected overnight. However, planar progs from both synoptic and convection-allowing models indicate that the northwestern rim of the surface-based warm sector (for effective-inflow parcels), with MLCAPE in the 100-500 J/kg range, should shift northward to northeastward from the lower TX Coast this evening to parts of the mid/upper coast below GLS by the end of the period. Forecast soundings suggest that, despite the technically surface-based nature of deeply moist boundary-layer air, a shallow stable layer near the surface will limit convective-scale lift of surface air. This will render any associated severe potential isolated and conditional, despite effective SRH commonly in the 250-450 J/kg range, and 45-55-kt effective-shear magnitudes. ...Edwards/Broyles.. 11/25/2022 $$ = = = 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) .