MD 1722 CONCERNING SEVERE POTENTIAL…WATCH LIKELY FOR WESTERN AND CENTRAL OK AND PART OF WESTERN NORTH TX
Mesoscale Discussion 1722 NWS Storm Prediction Center Norman OK 0236 PM CDT Sat Oct 21 2017 Areas affected...Western and central OK and part of western North TX Concerning...Severe potential...Watch likely Valid 211936Z - 212130Z Probability of Watch Issuance...95 percent SUMMARY...A new severe-weather watch will be coordinated soon across portions of the southern Plains. Thunderstorms are expected to develop by late afternoon across western Oklahoma and into parts of western North Texas, with storms becoming severe producing large hail and perhaps a tornado with the initial activity. Damaging winds will become a greater threat as storms form a line, advancing east across central Oklahoma into the evening. DISCUSSION...Despite the lack of lightning so far, trends in visible satellite imagery indicated sustained and deepening convection along the portion of the cold front advancing southward through western OK with some cooling of cloud tops. Farther south into western North TX, visible imagery indicated likely surface-based cumulus clouds forming from southeast of CDS into Wilbarger County. Objective analyses indicated an increase of low-level convergence across this latter area and the cold front, as a dryline shifts east through northwest TX. The warm sector has become moderately unstable (MLCAPE 2000-2500 J/kg) with weakening of surface-based inhibition per objective analyses along and just east of the surface boundaries. Additional surface heating and an increase in large-scale ascent, as an upper trough moves east into the southern Plains, are expected to aid in further weakening of the cap and strengthening storm development from late this afternoon through the evening. An increase in deep-layer shear will support supercells with the initial activity across western OK and western North TX, while upscale growth is expected into the evening, with damaging winds becoming the primary threat as a squall line evolves into central OK. ..Peters/Thompson.. 10/21/2017 ...Please see www.spc.noaa.gov for graphic product... ATTN...WFO...TSA...FWD...OUN... LAT...LON 34299996 35599953 36949829 36949689 36919663 36229668 35069706 34159745 33689809 33519899 33849990 34299996
from SPC Mesoscale Discussions http://bit.ly/1wClEfF
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