Subj : DAY2SVR: Nws Storm Prediction Center Norman Ok To : wx-storm@lists.illinois.edu From : COD Weather Processor Date : Wed Apr 05 2023 17:21:46 ACUS02 KWNS 051721 SWODY2 SPC AC 051720 Day 2 Convective Outlook NWS Storm Prediction Center Norman OK 1220 PM CDT Wed Apr 05 2023 Valid 061200Z - 071200Z ....THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS THE SOUTHERN APPALACHIANS INTO THE MID-ATLANTIC AND ACROSS DEEP SOUTH AND COASTAL TEXAS... ....SUMMARY... Isolated strong to severe thunderstorms are possible across parts of the southern Appalachians into the Mid-Atlantic, as well as across southern/coastal Texas, Thursday afternoon and evening. ....Synopsis... The upper wave currently over the north-central CONUS is expected to continue lifting to the northeast into southeastern Canada over the next 48 hours. By Thursday afternoon, a nearly straight mid-level jet streak will likely be in place from the Great Lakes region into southern Quebec. At the surface, a trailing cold front, currently pushing eastward across the Midwest and southern U.S., is expected to slow as it migrates into the Mid-Atlantic, Southeast, and TX Gulf Coast regions. Thunderstorms will likely be ongoing along portions of this boundary at the start of the period, and their longevity through the morning/early afternoon hours is uncertain due to an increasing displacement from stronger synoptic ascent to the north. Redevelopment along this boundary by late afternoon/early evening appears likely across the southeast states to the Mid-Atlantic region and may feature a few strong to severe thunderstorms. ....Mid-Atlantic and southern Appalachians... Thunderstorm development along the cold front appears probable along the southern Appalachians into the Mid-Atlantic region Thursday afternoon. The moist air mass currently in place across the Carolinas (characterized by mid/upper 60s dewpoints) will advect northward through the day and should support MLCAPE values upwards of 1000-1500 J/kg. Although the main upper-level jet axis will be displaced to the north of the region, 40-50 knot mid-level flow should provide favorable deep-layer shear for organized convection. While the overall parameter space will support supercells, storm motions and deep-layer shear vectors largely oriented along the initiating cold front suggest that initially discrete cells may grow upscale into clusters and/or lines. It remains somewhat uncertain how quickly this transition will take place, and a more robust hail/wind threat may emerge if discrete modes can be maintained through the afternoon. This conditional threat appears most probable across the DelMarVa/southeast VA region where recent CAM guidance shows the highest UH concentration, implying a regionally higher potential for organized discrete storms; however, confidence in this scenario remains too limited for higher risk probabilities. ....Deep South and coastal Texas... The cold front is expected to reach the TX Gulf coast by tonight/early Thursday morning and will likely stall offshore by late afternoon. Consequently, the potential for surface-based buoyancy will likely be limited to coastal areas. However, 7-8 C/km mid-level lapse rates (sampled in morning RAOBs) are expected to overspread deep south TX over the frontal intrusion. The approach of a weak mid-level perturbation (evident off the southern CA coast in water-vapor imagery) will likely augment low to mid-level isentropic ascent over the frontal surface, resulting in a broad region of precipitation with embedded thunderstorms. Given effective deep-layer shear on the order of 30-40 knots, a few stronger, more organized elevated cells are possible and may pose an isolated large hail threat. ...Moore/Gleason.. 04/05/2023 $$ = = = 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) .