Severe Storm Outlook Narrative (AC)
Issued by NWS
Issued by NWS
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506 ACUS01 KWNS 291243 SWODY1 SPC AC 291241 Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0741 AM CDT Wed May 29 2024 Valid 291300Z - 301200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS THIS AFTERNOON THROUGH LATE EVENING ACROSS THE NORTHERN/CENTRAL HIGH PLAINS AND IN SOUTHWEST TX... ...SUMMARY... Scattered strong storms posing a risk for severe hail and wind appear likely across the northern and central High Plains late this afternoon and evening. Isolated large hail will also be possible in southwest Texas. ...Northern/central High Plains this afternoon into tonight... A midlevel shortwave trough over the northern Rockies will continue eastward with associated lee troughing expected across the northern/central High Plains through the afternoon/evening. A corridor of modest low-level moistening (boundary-layer dewpoints potentially into the 50s) will occur along and east of the lee trough, where afternoon surface temperatures will warm well into the 80s beneath steep midlevel lapse rates and result in SBCAPE of 1000-2000 J/kg with minimal convective inhibition. Scattered high-based thunderstorms are expected to form by mid afternoon near the lee trough and spread eastward through late evening, with some potential for storms to be maintained into tonight in association with a strengthening low-level jet and warm advection. Occasional severe outflow gusts of 60-70 mph and isolated large hail of 1-1.5 inches in diameter will be the main threats with primarily multicell clusters and possibly some weak supercell structures given weak-modest deep-layer vertical shear (effective shear generally 25-30 kt). ...Southern Plains today into tonight... Widespread convective overturning has occurred across TX in the past 24 hours, with the remnants of a large MCS now weakening just off the lower TX coast. Lingering low-level moisture and steep lapse rates across the Trans-Pecos (northwest of the MCS remnants) could support isolated thunderstorm development this afternoon near the Davis Mountains. Here, MLCAPE in excess of 2000 J/kg and sufficiently long hodographs will favor splitting supercells capable of producing isolated large hail, potentially 2 inches in diameter or larger. Otherwise, marginally severe storm development may occur near the upper TX coast later today with a remnant MCV on the edge of the richer low-level moisture. The southern portion of the central High Plains convection may persist through tonight and grow into a loosely organized MCS from western KS southward into the TX Panhandle and western OK, where the storms will encounter gradually increasing low-level moisture in a warm advection regime. A few strong gusts and isolated/marginally severe hail may occur with the strongest embedded storms. ...Central Appalachians/Mid-Atlantic this afternoon... A midlevel trough now over OH will progress eastward to the Mid-Atlantic coast by early tonight. Low-level moisture will be relatively limited in advance of the midlevel trough and a weak surface reflection, but surface heating and steepening of low-level lapse rates will contribute to weak SBCAPE of 250-500 J/kg. Scattered, low-topped thunderstorms will be possible this afternoon across PA/MD/VA and convection will spread to the coast this evening. The steep low-level lapse rates will promote gusty outflow winds, but severe/damaging winds appear unlikely given marginal buoyancy and weak low-level flow to limit momentum transfer. ..Thompson/Grams.. 05/29/2024 $$