Subj : MESO: Mesoscale Discussion 1256 To : wx-storm@lists.illinois.edu From : COD Weather Processor Date : Sun Jun 25 2023 19:22:46 ACUS11 KWNS 251922 SWOMCD SPC MCD 251922=20 KYZ000-INZ000-252045- Mesoscale Discussion 1256 NWS Storm Prediction Center Norman OK 0222 PM CDT Sun Jun 25 2023 Areas affected...Portions of southern IN and southern/central KY Concerning...Severe potential...Tornado Watch likely=20 Valid 251922Z - 252045Z Probability of Watch Issuance...80 percent SUMMARY...The threat for tornadoes, very large hail, and damaging winds should increase this afternoon. Tornado watch issuance will likely be needed in the next couple of hours. DISCUSSION...Recent attempts at convective initiation have been noted across parts of southern IL along and just ahead of a surface cold front. Latest visible satellite imagery also shows an outflow boundary from prior convection arcing northward from middle TN into western KY and far southwestern IN, intersecting the cold front in far southeastern IL. Low-level winds to the west of the outflow boundary have generally veered to west-southwesterly. But surface and boundary-layer winds along/east of this boundary are backed to south-southeasterly. A rather unstable and strongly sheared environment is present across southern IN into western/central KY ahead of the cold front, and near the outflow boundary. Steep mid-level lapse rates and strong diurnal heating of a very moist low-level airmass are contributing to 1500-2500+ J/kg of MLCAPE this afternoon. A 50+ kt mid-level westerly jet and veering wind profile with height through mid levels is supporting 45-55+ kt of deep-layer shear. Supercells are expected to continue forming with southward extent along the cold front into southwestern IN. Very large hail will be a threat with this initially discrete development. The tornado threat is less clear in the short term due to weak low-level winds. But, backed southerly winds to the east of the outflow boundary along with gradually increasing winds associated with an approaching low-level jet should support locally greater 0-1 km SRH, and some threat for tornadoes, as convection spreads eastward into central KY later this afternoon and early evening. Damaging winds will also be possible with any upscale growth into small clusters that can occur. Given the potential for robust supercells to develop along/near the OH River in the next 1-2 hours, Tornado Watch issuance will likely be needed. ...Gleason/Grams.. 06/25/2023 ....Please see https://urldefense.com/v3/__http://www.spc.noaa.gov__;!!DZ3fj= g!4nBhxPJyodAf-8E0J-DCqBMQBxg7zsL2RRhp-vtfoIxZkgYmTzlJXX35QQCdK-xkSBIrxQNOD= IomuyAsRcDGOuR-jeg$ for graphic product... ATTN...WFO...LMK...PAH... LAT...LON 37958793 38328757 38708546 38128502 37328545 36808631 36788723 37298795 37958793=20 =3D =3D =3D 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) .