Subj : DAY1SVR: Day 1 Convective Outlook To : wx-storm@lists.illinois.edu From : COD Weather Processor Date : Tue Aug 22 2023 12:53:44 ACUS01 KWNS 221253 SWODY1 SPC AC 221252 Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0752 AM CDT Tue Aug 22 2023 Valid 221300Z - 231200Z ....THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS SOUTH TEXAS...THE GREAT LAKES AND UPPER GREAT LAKES... ....SUMMARY... Storms with gusty winds and/or a tornado or two are possible across parts of south Texas today in association with Tropical Storm Harold. 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 again late tonight. ....South/South-Central Texas... Tropical Storm Harold is expected to continue west-northwestward toward and across Deep South Texas today. Reference the National Hurricane Center for the latest details. Early morning WSR-88D VWP data and 00z-12z observed sounding trends reflect a strengthening of low-level easterlies in association with Harold, even while the low-level circulation has not been overly well-defined. A multi-layer cloud canopy preceding Harold may hinder destabilization and updraft accelerations somewhat today, but at least some potential will exist for transient supercells with a brief tornado risk, particularly this morning through early afternoon, given the moist environment and moderately enlarged low-level hodographs. Any tornado/convective wind risk should diminish by late afternoon, and almost certainly by sunset. ....Upper Great Lakes... Convective potential including some severe risk is possible this morning, but probably more so late tonight. On the north-northeast periphery of the prominent Midwest-centered upper ridge, a low-level jet and related warm/moist advection is contributing to scattered thunderstorms early this morning along the Wisconsin/Michigan border vicinity, as well as other parts of northern Michigan. A few stronger storms may yet occur this morning with some hail potential, but any such severe risk should remain very marginal/isolated. A stronger low-level jet tonight is expected to result in a repeat scenario with overnight-maximized thunderstorm potential, but just a bit farther east-southeast centered across Upper Michigan and northern Lower Michigan. Some of the stronger storms could produce hail in the presence of 1500+ J/kg of elevated buoyancy and seasonally strong northwesterly mid/high-level flow. ....Great Basin... A moisture plume and a belt of enhanced low/mid-level 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, moist profiles will render weak mid-level lapse rates and limit the overall magnitude of destabilization and the severe threat. It seems plausible given the shear/buoyancy that at least some risk for marginal transitory supercell structures and organized multicells will evolve, and pose a localized threat for severe wind gusts and possibly a brief tornado. ....Interior Northwest... At least widely scattered thunderstorm development is expected this afternoon from eastern Oregon into Idaho and western Montana, 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. This will continue to be reevaluated in subsequent outlooks. ...Guyer/Goss.. 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) .