WeatherWheeler35 Posted May 13 Share Posted May 13 SPC AC 131615 Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 1115 AM CDT Sat May 13 2023 Valid 131630Z - 141200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS THIS AFTERNOON AND EVENING FROM IOWA INTO CENTRAL ILLINOIS... ...SUMMARY... Thunderstorms associated with a few tornadoes, wind damage and large hail will be possible today from Iowa into central Illinois. Isolated strong to severe storms are also possible across southern Oklahoma and East Texas as well as the eastern Virginia/North Carolina border vicinity. ...IA into the Mid MS Valley... Recent surface analysis places a low about 30 miles northwest of OFK in far northeast NE. A cold front extends southward from this low through central KS and then back southwestward from north-central trough southwest OK. Surface pattern east of the low is a bit more complex, with a warm front extending from the low southeastward across southwest IA and into north-central MO. This warm front intersects a residual stationary boundary near DSM, with this stationary boundary continuing eastward across the OH Valley. The surface low is forecast to make modest eastward progress throughout the day, with the warm front continuing to move northward as well. However, the presence of the stationary boundary may impeded the northern progression of the warm front somewhat. Expectation is a corridor or mid to upper 60s dewpoints to extend from east-central MO/southern IL northwestward through central IA. This corridor will likely be south of the warm front, but east of dryline-like boundary that is expected to mix eastward with time. Moderate buoyancy is anticipated within this corridor as well, contributing to likely thunderstorm development as the boundary moves eastward. Southeasterly surface winds will beneath modest westerlies will contribute to moderate deep-layer vertical shear and the potential for more organized storm structures capable of all severe hazards across IA. Strong low-level buoyancy (i.e. 0-3 km MLCAPE greater than 150 J/kg) and low-level vorticity throughout the corridor of southeasterly winds could increase what would otherwise be a low probability tornado risk given anticipated shear magnitudes. Farther south, surface winds will be weaker with a more outflow-dominant storm structure anticipated. Here, some clustering is also possible, with storms then forward-propagating into west-central IL. ...Central/Southern OK...Arklatex...East TX... Widespread thunderstorm development is anticipated this afternoon from central OK eastward into the Arklatex and East TX amid the tropical air mass in place. Vertical shear is weak, limiting storm organization and the overall severe potential. Even so, a few water-loaded downbursts and maybe even a tornado or two remain possible. This low-probability tornado threat appears maximized across southern OK, where greater low-level vorticity is expected. ...VA Tidewater...Northeast NC... An upper trough is rotating quickly southeastward into New England, with a cold front sagging southward across WV/VA. This boundary will move into a relatively moist airmass over southern VA this afternoon, resulting in thunderstorm development. Strengthening westerly flow aloft and relatively steep boundary-layer lapse rates may result in a few strong wind gusts in the more intense cells. Activity will move into northern NC this evening before weakening. ..Mosier/Moore.. 05/13/2023 CLICK TO GET WUUS01 PTSDY1 PRODUCT NOTE: THE NEXT DAY 1 OUTLOOK IS SCHEDULED BY 2000Z Quote Link to comment Share on other sites More sharing options...
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