Subj : DAY2SVR: Nws Storm Prediction Center Norman Ok To : wx-storm@lists.illinois.edu From : COD Weather Processor Date : Tue Sep 19 2023 05:49:58 ACUS02 KWNS 190549 SWODY2 SPC AC 190548 Day 2 Convective Outlook NWS Storm Prediction Center Norman OK 1248 AM CDT Tue Sep 19 2023 Valid 201200Z - 211200Z ....THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS FOR PORTIONS OF THE SOUTHERN PLAINS... ....SUMMARY... Isolated strong to severe thunderstorms are possible across the southern Plains Wednesday afternoon and evening. ....Synopsis... An upper ridge will develop across the southern Plains as a mid-level trough amplifies over the northwestern U.S. tomorrow/Wednesday. In response to this broad upper troughing, surface lee troughing will take place across the Plains states, supporting low-level moisture advection beneath cooler temperatures aloft, resulting in a buoyant warm sector. Though deep-layer ascent will be lackluster across the southern Plains given the approach of an upper ridge, adequate shear and instability will be in place to support an isolated severe thunderstorm or two if convective initiation and sustenance can take place. ....Southern Plains... At least some residual clouds, showers, and thunderstorms should be ongoing across the southern Plains (remnant from Day 1) as a mid-level impulse progresses toward the MS Valley and de-amplifies through morning. Clearing should occur through the afternoon as upper ridging sets in over the southern Plains. Here, surface temperatures should warm into the upper 80s/low 90s F amid low to mid 60s F dewpoints, overspread by 8 C/km mid-level lapse rates, boosting SBCAPE to 1500-2500 J/kg. By late afternoon, a surface mesolow may become established across southwestern OK/northwestern TX, resulting in backed surface winds, which will be overspread by a 30-35 kt southwesterly low-level jet and 35-40 kts of northwesterly 500 mb flow. This veering/strengthening vertical wind profile will support elongated hodographs, and over 40 kts of effective bulk shear. An outflow boundary from earlier convection may become established over central OK, where multiple guidance members depict curved low-level hodographs and over 200 m2/s2 of effective SRH. Should convective initiation take place and a storm becomes sustained (especially near the outflow boundary), supercell structures would be likely, accompanied by a localized threat for a severe gust, instance of large hail, or a tornado. However, height rises through the day cast doubt on appreciable convective coverage, with some of the latest high-resolution ensemble guidance depicting little in the way of storm coverage by Wednesday evening. A Category 1/Marginal Risk remains in place given the favorable kinematic/thermodynamic environment. However, severe probabilities may be removed if the lack of thunderstorm development becomes more apparent. ...Squitieri.. 09/19/2023 $$ = = = To unsubscribe from WX-STORM and you already have a login, go to https://lists.illinois.edu and use the "Unsubscribe" link. Otherwise email Chris Novy at cnovy@cox.net and ask to be removed from WX-STORM. --- SBBSecho 3.14-Linux * Origin: capitolcityonline.net * Telnet/SSH:2022/HTTP (1:2320/105) .