Severe Storm Outlook Narrative (AC)
Issued by NWS
Issued by NWS
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271 ACUS01 KWNS 230525 SWODY1 SPC AC 230523 Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 1223 AM CDT Mon Sep 23 2024 Valid 231200Z - 241200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS FROM THE OZARKS TO THE OHIO/TENNESSEE VALLEYS REGION... ...SUMMARY... Isolated strong to severe thunderstorms are possible from the Ozarks into parts of the Tennessee and lower Ohio Valleys. ...Ozarks to TN/OH Valley Region... Northern-stream short-wave trough is forecast to dig into the northern Plains later this afternoon, which will encourage the positive-tilt trough over the central Plains to eject east, and deamplify over the MS Valley late in the period. This evolution is expected to aid weak surface wave/low development along the synoptic front, mostly likely over northern AR early in the period. Latest model guidance suggests this weak feature will track northeast into southern IN by 24/12z. While the surface front is not particularly sharp, this boundary will serve as the focus for scattered convection through the period. Pre frontal boundary-layer heating will prove instrumental in destabilization as mid-level lapse rates should remain weak through the period. Latest NAM suggests 0-3km lapse rates will steepen across eastern AR into western KY by early afternoon, which will result in MLCAPE in excess of 1000 J/kg, coincident with modest 0-6km bulk shear. Forecast soundings favor multi cell updrafts with some organizational potential, as effective shear will be on the order of 30kt along this pre frontal corridor. At this time it appears most updrafts will struggle to generate more than marginally strong gusts, or perhaps some hail approaching 1 inch. Most robust updrafts should develop by late morning and continue into the early-evening hours before nocturnal cooling lessens buoyancy. ..Darrow/Thornton.. 09/23/2024 $$