SPC 1630Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 1022 AM CST Sat Jan 30 2021 Valid 301630Z - 311200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS FROM NORTHEAST OKLAHOMA...SOUTHEAST KANSAS INTO SOUTHWEST MISSOURI AND NORTHWEST ARKANSAS... ...SUMMARY... Isolated severe thunderstorms remain possible this afternoon and early evening from northeast Oklahoma into southwest Missouri,as well as parts of southeast Kansas and northwest Arkansas. ...OK/KS/MO/AR this afternoon... Only minor adjustments have been made to previous forecast with main limiting factor being expected very weak buoyancy. A well-defined midlevel shortwave trough moving through western OK as of late this morning will continue east-northeastward over OK/KS today and MO/AR this evening. The associated surface cyclone will likewise develop eastward along the KS/OK border, reaching southwest MO this evening. Low-level moisture return within the cyclone warm sector remains limited by ongoing air mass modification over the Gulf of Mexico in the wake of a prior frontal intrusion. However, midlevel moistening and lapse rates have been sufficient to support clusters of elevated thunderstorms (rooted near 700 mb) this morning in the zone of ascent preceding the midlevel trough. Ongoing elevated thunderstorms will likely persist from eastern OK, southeast KS, and western AR into early afternoon and southwest MO through mid afternoon. In the wake of the elevated convection, a zone of surface heating along a dryline will overlap a narrow corridor of boundary-layer dewpoints of 50-55 F from southeast KS across northeast OK, from midday into the afternoon. Destabilization in this narrow corridor might become sufficient for surface-based convection to develop near and immediately south of the surface cyclone. Steep low-midlevel lapse rates and 500 mb temperatures of -20 C and colder may support MLCAPE of 250-500 J/kg, with a brief window of opportunity for low-topped supercells within the left-exit region of the midlevel jet. Isolated damaging gusts and hail, as well as an isolated tornado, remain possible this afternoon with peak buoyancy, before diminishing rapidly this evening with eastward extent and the onset of nocturnal cooling. Given lingering concerns regarding destabilization potential, will maintain MRGL category for this outlook and continue to monitor for a possible SLGT risk in the upcoming 20Z update. ..Dial/Jewell.. 01/30/2021
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