SPC 2000Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0253 PM CDT Thu Sep 30 2021 Valid 302000Z - 011200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS THIS AFTERNOON THROUGH LATE EVENING ACROSS WEST CENTRAL AND SOUTHWEST TX... ...SUMMARY... Large hail and severe thunderstorm gusts are possible this afternoon through late evening across west-central and southwest Texas. ...Discussion... No appreciable change was made to the previous convective outlook. ..Smith.. 09/30/2021 .PREV DISCUSSION... /ISSUED 1115 AM CDT Thu Sep 30 2021/ ...Southern Plains this afternoon through late evening... A surface cold front will move slowly southward from the TX South Plains to the Permian Basin today into tonight, with slower eastward motion of the boundary across western/central OK (augmented by convective outflow). A reservoir of mid-upper 60s boundary-layer dewpoints is present this morning from the Rio Grande Valley into central/north TX to the southeast of the cold front, and regional 12z soundings showed midlevel lapse rates near 8 C/km atop this moist boundary layer. Surface heating in cloud breaks will boost MLCAPE into the 2000-3000 J/kg range this afternoon from southern OK into central/southwest TX. Thunderstorm clusters are ongoing as of late morning from central OK into northwest TX and southeast NM, and storm coverage will increase through early-mid afternoon along and ahead of the cold front as convective inhibition weakens and a weak midlevel shortwave trough ejects northeastward around the southeast periphery of a closed low over AZ. Thermodynamic profiles will support some threat for large hail/downburst winds with multicell clusters from southwest/south central OK southwestward, but the somewhat greater wind/hail threat is expected across southwest TX where effective bulk shear of 30-40 kt will support a few supercells. Occasional thunderstorm outflow winds of 60-70 mph and large hail of 1-1.75" diameter will be possible with the strongest storm clusters/supercells through late evening. Read more LIVE: spc.noaa.gov
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