Subj : DAY1SVR: Day 1 Convective Outlook To : wx-storm@lists.illinois.edu From : COD Weather Processor Date : Wed Sep 27 2023 05:09:25 ACUS01 KWNS 270509 SWODY1 SPC AC 270508 Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 1208 AM CDT Wed Sep 27 2023 Valid 271200Z - 281200Z ....THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS OVER PORTIONS OF FAR SOUTHEAST ILLINOIS...SOUTHERN INDIANA AND WESTERN/CENTRAL KENTUCKY... ....SUMMARY... Thunderstorms producing a strong gusts and hail will be possible across parts of the Ohio Valley into Middle Tennessee through this evening. ....Lower Ohio Valley Vicinity... A weak upper low and attendant trough will shift slowly eastward across the Midwest/Lower OH Valley vicinity through tonight. Deep-layer flow will remain modest with this system, with generally around 20-30 kt westerly flow from around 850mb through 500 mb. however, vertically veering wind profiles will support about 30 kt effective shear magnitudes. This should allow for a least some transient organized thunderstorms today into this evening. At the surface, a weak low over IL will shift east toward IN and a warm front will arc east/southeast from roughly central IL into southern IN. Ongoing convection and cloud cover this morning may linger, through midday near/north of the OH River and also spread east into eastern KY/southwest OH/eastern IN. This activity may pose a low-end wind/hail risk while being somewhat elevated through the morning. Clearing south of the warm front should support pockets of heating from southern IL/southwest IN into western/central KY. Surface dewpoints in the mid 60s and modest midlevel lapse rates will contribute to MLCAPE values around 1000-1500 J/kg. Given vertically veering wind profiles contributing to enlarged, curved low-level hodographs, some potential for storm rotation/transient supercells exists. Isolated large hail will be possible with this activity during the late afternoon/evening. Steepening low-level lapse rates also may support isolated strong/damaging gusts, with some potential for clustering into the evening. There is some uncertainty in how much inhibition may linger into peak heating due to early cloud cover/convection. However, low-level shear around 20-30 kt and effective SRH values around 200 m2/s2 suggest a tornado also could be possible with any supercell that develops and can be maintained, especially near the warm front or residual outflows. Though this risk appears to be rather low/conditional at this time. ...Leitman.. 09/27/2023 $$ = = = 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) .