Subj : DAY1SVR: Day 1 Convective Outlook To : wx-storm@lists.illinois.edu From : COD Weather Processor Date : Tue Aug 22 2023 05:39:42 ACUS01 KWNS 220539 SWODY1 SPC AC 220538 Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 1238 AM CDT Tue Aug 22 2023 Valid 221200Z - 231200Z ....THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS PORTIONS OF SOUTH TEXAS...EASTERN GREAT BASIN...AND NORTHERN WISCONSIN INTO LOWER MICHIGAN... ....SUMMARY... Storms with gusty winds and possibly a tornado or two will be possible across parts of south Texas today, in association with a tropical cyclone. Isolated strong to severe storms will also be possible from northern Arizona into Utah and southwest Wyoming, and also across the upper Great Lakes region this morning and late tonight. ....South-central into Deep South TX... Tropical Depression #9 is forecast by the National Hurricane Center to strengthen into a tropical storm early this morning and move ashore Deep South TX (refer to NHC for the latest forecast details). Convection associated with the tropical system will reside in a very moisture-rich airmass and spread inland into the Rio Grande Valley during the day. Transient supercells will become possible with the more robust cellular convection and potentially yield a risk for a tornado or two and perhaps locally strong/severe gusts. This threat for stronger storms will gradually shift westward and diminish from east to west by early evening. ....Upper Great Lakes vicinity... Showers and thunderstorms will likely be ongoing this morning in association with warm air advection and nose of a LLJ north of a surface front. A few stronger storms are possible within an airmass characterized by 1500 J/kg MUCAPE and shear profiles supporting organized storm structures. This activity will likely dissipate by late morning. A reintensification of a north-central U.S. LLJ will occur tonight with the terminus near the eastern WI/Lower MI vicinity. Steep 700-500 mb lapse rates and ample MUCAPE and strong northwesterly mid to high-level flow, will favor at least an isolated threat for severe hail. Models vary regarding the robustness of simulated elevated storms and their corresponding hail potential risk. Will re-evaluate this potential scenario in later outlooks. ....Great Basin vicinity... A moisture plume and a belt of somewhat enhanced low/midlevel flow will persist across portions of the Great Basin to the west of a large mid-level anticyclone. Scattered thunderstorms will develop via diurnal heating and persist into the evening. While deep-layer shear will be sufficient for storm organization, the moist profiles will render weak midlevel lapse rates and limit the overall magnitude of destabilization and the severe threat. It seems plausible given the shear/buoyancy that at least some low risk for marginal transitory supercell structure and organized multicells will evolve and pose a localized threat for severe gusts and possibly a brief tornado. ....Interior Northwest... Scattered thunderstorm development is possible this afternoon from eastern OR into ID and western MT, associated with a mid/upper-level shortwave trough moving across the Pacific Northwest. Deep-layer shear will be sufficient to support somewhat organized convection, but it remains uncertain as to whether instability will be sufficient to support a severe hail/wind threat. ...Smith/Weinman.. 08/22/2023 $$ = = = 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) .