ZCZC SPCSWOMCD ALL ACUS11 KWNS 151728 SPC MCD 151728 TXZ000-152000- Mesoscale Discussion 0259 NWS Storm Prediction Center Norman OK 1228 PM CDT Fri Mar 15 2024 Areas affected...Portions of south-central and southeast Texas Concerning...Severe potential...Watch likely Valid 151728Z - 152000Z Probability of Watch Issuance...80 percent SUMMARY...Severe storms capable of producing very large hail (2+ inch) and severe winds are expected across portions of south-central and southeast Texas this afternoon. A watch will likely be issued in the next couple hours for parts of the area. DISCUSSION...Latest surface observations and visible satellite imagery indicate an east/west-oriented outflow-modified cold front gradually stalling across parts of south-central into southeast TX this afternoon. Given that much of this area is on the backside of a departing shortwave trough moving east-northeastward across east TX, overall coverage of storms is a bit uncertain. Nevertheless, as the frontal circulation intersects a gradually deepening moist layer amid pockets of diurnal heating, at least isolated to widely scattered storm development is expected this afternoon -- possibly aided by weak low-level warm advection atop the frontal surface/cold pool. An additional focus for storm development will be over the southern portion of the Edwards Plateau, where the front intersect the higher terrain amid upslope flow enhancements. The latest ACARS soundings from San Antonio TX sampled steep midlevel lapse rates (near 8 C/km) associated with an EML atop a gradually deepening moist layer extending through 1 km AGL. Continued diurnal heating of this moist layer should contribute to moderate/strong instability (2500-3000 J/kg MLCAPE). In addition, a belt of 40-50 kt midlevel west-southwesterly flow above veering low-level flow will yield 40-50 kt effective shear. This will support the development of initially semi-discrete supercell clusters, capable of producing very large hail (some greater than baseball-sized), along with locally severe winds. While a tornado or two cannot be entirely ruled out with these storms, low-level shear will not be particularly strong, and the development of strong cold pools could reduce the risk to an extent. With time, localized upscale growth into several organized clusters is possible, with an increasing wind risk and continued large hail threat with east-southeastward extent. ..Weinman/Goss.. 03/15/2024 ...Please see www.spc.noaa.gov for graphic product... ATTN...WFO...LCH...HGX...CRP...EWX... LAT...LON 29110097 29450126 29890135 30100106 30140073 30049826 30169736 30359635 30449568 30439523 30329461 30039456 29589492 29139556 28829632 28699705 28639790 28609943 28720015 28860062 29110097 NNNN