Subj : DAY1SVR: Day 1 Convective Outlook To : wx-storm@lists.illinois.edu From : COD Weather Processor Date : Wed Aug 23 2023 01:04:17 ACUS01 KWNS 230104 SWODY1 SPC AC 230102 Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0802 PM CDT Tue Aug 22 2023 Valid 230100Z - 231200Z ....THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF THE INTERMOUNTAIN WEST...GREAT LAKES AND SOUTH-CENTRAL TEXAS... ....SUMMARY... Thunderstorms associated with a marginal wind-damage threat will continue across parts of the Intermountain West this evening. A marginal tornado threat will continue across parts of south-central Texas this evening. Marginally severe hail is expected to develop in parts of the Great Lakes tonight. ....Intermountain West... The latest water-vapor imagery shows a mid-level anticyclone over much of the central U.S. South-southwesterly mid-level flow is located over the Intermountain West, where a north-to-south axis of low-level moisture is present. Along and near this axis, surface dewpoints are in the 55 to 60 F range. This is contributing to weak instability, with the RAP showing MLCAPE in the 250 to 500 J/kg range. Near this corridor of instability, from northwest Arizona into western Wyoming, regional WSR-88D VWPs and RAP forecast soundings have 0-6 km shear in the 40 to 50 knot range. This will support a marginal severe threat with the stronger multicells over the next few hours. The strong deep-layer shear, along with steep low to mid-level lapse rates from 7 to 8 C/km will support a continued marginal wind-damage threat. ....South-central Texas... Tropical Depression Harold is currently located in northern Mexico to the northwest of Laredo, Texas. Bands associated with Harold extend southeastward across south-central Texas. RAP forecast soundings across south-central Texas this evening have strong speed shear in the lowest 2 km above ground level, along with directional shear in the low to mid-levels. This is contributing to a curved hodograph, which will likely support a marginal tornado threat this evening. This potential will gradually shift westward toward the Rio Grande River this evening, as Harold moves west-northwestward across northern Mexico. .....Great Lakes... The latest water-vapor imagery shows a northwest flow pattern from the northern U.S. southeastward to the Atlantic Seaboard, with a mid-level anticyclone over the central states. A subtle shortwave trough and an associated mid-level jet, appear to be moving into the western Great Lakes region. This feature will support scattered thunderstorm development tonight along the northeastern edge of an unstable airmass in the central Great Lakes region. RAP forecast soundings late tonight over northern lower Michigan, near the area with greatest convective potential, have MUCAPE in the 1500 to 2000 J/kg range, with effective shear of 35 to 40 knots. This, combined with 700-500 mb lapse rates near 7 C/km may be enough for a marginal hail threat. The threat is expected to be maximized between 09Z and 12Z. ...Broyles.. 08/23/2023 $$ = = = 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) .