Subj : DAY2SVR: Nws Storm Prediction Center Norman Ok To : wx-storm@lists.illinois.edu From : COD Weather Processor Date : Wed May 07 2025 17:30:57 ACUS02 KWNS 071730 SWODY2 SPC AC 071729 Day 2 Convective Outlook NWS Storm Prediction Center Norman OK 1229 PM CDT Wed May 07 2025 Valid 081200Z - 091200Z ....THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS OVER THE SOUTHERN APPALACHIANS AND RIO GRANDE VALLEY... ....SUMMARY... Scattered damaging winds and severe hail are possible over the southern Appalachians on Thursday afternoon to early evening. A swath of large hail and severe wind is possible along the Rio Grande Valley from mid-afternoon to evening. ....Synopsis... An elongated, positive-tilt mid/upper trough from southeast Canada to the Rio Grande will slowly progress east on Thursday. At least a trio of embedded shortwave impulses will aid in corridors of modest large-scale ascent, amid a pervasive swath of 35-50 kt 500-mb west-southwesterlies across the South into the East. Given the highly positive-tilt orientation of the trough, attendant surface reflections will remain weak. A minor surface wave over the Mid-South should decay by early evening, while a separate low drifts northeast from the lee of the southern Appalachians to VA. ....Mid-South to southern Appalachians... Multiple corridors of scattered thunderstorm development are expected by Thursday afternoon, ahead of a shortwave impulse drifting from the Ozarks across a portion of the Mid-South. Lingering activity/cloud cover during the morning will serve as the northern limiter to severe potential, along with weaker deep-layer shear closer to the trough. The most likely zone for a scattered severe hail and damaging wind threat appears to be across the southern Appalachians vicinity where MLCAPE of 1000-1500 J/kg and 30-40 kt effective bulk shear are anticipated. Here, a few supercells may congeal into an organized cluster or two. Farther west, lesser values of instability and shear should yield a more isolated/marginal severe threat. ....TX Rio Grande Valley... A low-amplitude shortwave impulse should progress from northern Chihuahua along the Rio Grande. Numerous thunderstorms are expected ahead of the impulse across the southern Trans-Pecos/Big Bend by mid-afternoon and adjacent Coahuila. Uncertainty increases with how this activity will evolve downstream Thursday evening, potentially remaining primarily across northeast Mexico or growing upscale across the Lower Rio Grande Valley into Deep South TX as it impinges on richer low-level moisture. With low-level northeasterlies beneath mid/upper-level west-southwesterlies, an elongated/nearly straight-line hodograph is expected. This should foster splitting supercell structures, which could congeal into a cluster/small MCS. The primary limiting factor to more robust intensity will be a lack of steep mid-level lapse rates amid weak warm advection. Still, enough signal exists to warrant a level 2/SLGT risk. ....Southern Mid-Atlantic... Modest mid-level forcing for ascent should promote isolated to scattered thunderstorms developing off the central Appalachians and Blue Ridge Mountains on Thursday afternoon. A well-mixed boundary layer with weak MLCAPE and moderate effective shear will allow for a few transient/weakly organized cells during the afternoon. This could promote small hail amid weak mid-level lapse rates and support a primary threat of localized damaging winds. ....Southern Atlantic Coast... Sufficient mid-level westerlies are expected to support a few weakly organized storms along the sea breeze boundary on Thursday afternoon. Mid-level temperatures should remain cold enough to support an isolated severe hail threat. A warm/moist boundary layer will also foster isolated strong to severe gusts. ...Grams.. 05/07/2025 $$ = = = 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 3.20-Linux * Origin: capitolcityonline.net * Telnet/SSH:2022/HTTP (1:2320/105) .