Subj : DAY2SVR: Nws Storm Predic To : All From : Mike Powell Date : Wed Apr 26 2023 16:00:00 ACUS02 KWNS 261728 SWODY2 SPC AC 261726 Day 2 Convective Outlook NWS Storm Prediction Center Norman OK 1226 PM CDT Wed Apr 26 2023 Valid 271200Z - 281200Z ....THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FOR PARTS OF DEEP SOUTH TEXAS AND PORTIONS OF SOUTHERN LOUISIANA INTO SOUTHWESTERN GEORGIA AND THE FLORIDA PANHANDLE... ....SUMMARY... Scattered severe storms are expected along much of the Gulf Coast Thursday, from portions of southern Texas and southern Louisiana into the Florida Panhandle. Damaging gusts, large hail, and a few tornadoes will all be possible. ....Synopsis... A mid-level trough will sweep across the Southeast U.S. as a second upper trough amplifies over the central Rockies tomorrow/Thursday. Modest surface-low intensification is likely by late morning to early afternoon across the Lower MS Valley, which should encourage an increase in low-level moisture advection, buoyancy and flow/shear along the Gulf Coast. In addition to an increase in convective coverage, strong to severe thunderstorm development is likely, with all severe hazards possible. Across the central Rockies into the central High Plains, deep-layer ascent with the deepening upper trough will encourage enough lift within a marginally buoyant airmass to promote at least scattered thunderstorms, some of which may become strong to locally severe. ....Gulf Coast Region... Strong to potentially severe thunderstorms should be ongoing at the start of the period across far eastern TX into LA ahead of a cold front sweeping southward across the Southern Plains. As the surface low gradually intensifies and drifts from the Lower MS Valley to the TN Valley during the late morning/afternoon hours, the cold front should continue to sag south/eastward. Increasing surface-850 mb flow, moisture and convergence ahead of the storms should support an increase of MLCAPE to 1000 J/kg along with convective coverage and intensity by late morning/early afternoon. Several storms should merge into a QLCS, with the possibility of a few discrete storms also developing ahead of the line. Damaging gusts should be the main threat with the QLCS, though a few tornadoes may also occur given modest low-level hodograph curvature. The latest high-resolution guidance consensus also depicts a couple of isolated splitting supercell structures initiating off of the trailing cold front across deep south TX during the late morning/early afternoon. Before moving offshore, the supercells may produce damaging gusts and large hail. 8+ C/km lapse rates atop near 70 F surface dewpoints will support 2000-3000 J/kg MLCAPE amid elongated, straight hodographs. As such, an instance or two of 2+ inch diameter hail cannot be ruled out. Lastly, guidance consensus also depicts discrete storms (perhaps transient supercells) initiating off of a sea-breeze boundary across northeast FL during the afternoon. 2000+ J/kg MLCAPE amid elongated hodographs suggest that isolated damaging gusts and large hail may accompany one or two of the stronger storms. ....Lower MS Valley... As the primary round of thunderstorms progresses along the Gulf Coast through the afternoon, a second cluster of strong storms is expected to develop closer to the surface low, beneath the core of a 500 mb jet streak. Colder temperatures and increasing speed shear above 700 mb will support 7.5+ C/km mid-level lapse rates amid elongated, straight hodographs. As such, a few storms should become organized enough to support an isolated severe threat through the afternoon, with large hail and damaging gusts the main threats. ....Central Rockies/Central High Plains... By mid afternoon, bands of low-topped thunderstorms are expected to develop behind the cold front as cold temperatures aloft/8+ C/km mid-level lapse rates overspreads a dry, deeply mixed boundary layer. Forecast soundings in this dry post-cold-frontal regime depict very thin, meager CAPE profiles. Nonetheless, 30-40 F surface temperature/dewpoint spreads and associated boundary-layer lapse rates approaching 9 C/km may encourage efficient evaporative cooling in the stronger storms to support isolated strong surface winds gusts, one or two of which may reach severe limits. ...Squitieri.. 04/26/2023 $$ --- SBBSecho 3.14-Linux * Origin: Ilink: CCO - capitolcityonline.net (454:1/105) .