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Mesoscale Discussion 0590 NWS Storm Prediction Center Norman OK 1013 AM CDT Tue May 11 2021 Areas affected...Parts of central through northeast Texas Concerning...Severe potential...Watch possible Valid 111513Z - 111615Z Probability of Watch Issuance...40 percent SUMMARY...Thunderstorms are expected to continue to initiate and become increasingly widespread north through northeast of the Edwards Plateau and adjacent Big Country through the Interstate 30/20 corridors by Noon to 2 PM CDT. This may include at least some risk for severe hail early, with potential to organize later this afternoon, if not before. It is not yet certain a watch will be needed, but trends will continue to be monitored for this possibility. DISCUSSION...Latest model output indicates a substantial strengthening of large-scale ascent north/northeast of the Edwards Plateau, across parts of the Texas Big Country through the Interstates 30/20 corridors of north central and northeast Texas by 17-19Z. This is forecast to occur in response to strengthening lower/mid-tropospheric warm advection, beneath increasingly divergent high-level flow, as a west-southwesterly subtropical jet streak continues to nose across the northern Mexican Plateau through the Texas Gulf coast vicinity. This lift will largely be focused above at least shallow cool/stable surface-based air to the north of stalled/slow moving frontal zone now extending across the upper Texas coastal plain through parts of Deep South Texas and the lower Rio Grande Valley. However, seasonably moist air above the frontal inversion, and beneath steep lapse rates associated with elevated mixed-layer air, is contributing to moderate to large CAPE, supportive of vigorous thunderstorm development. While high-level flow is strong, lower/mid tropospheric flow is somewhat modest to weak. Coupled with the likelihood for increasingly widespread convection through midday and early afternoon, hail potential in the longer term remains unclear. However, given the initial thermodynamic profiles, there may be a window of opportunity for large hail in the initially more discrete early storm development. ..Kerr/Thompson.. 05/11/2021 ...Please see www.spc.noaa.gov for graphic product... ATTN...WFO...SHV...HGX...FWD...EWX...SJT... LAT...LON 32609949 32959809 33149610 32439453 31079569 30959757 30349983 30570081 31300040 32609949 |
