Subj : DAY1SVR: Day 1 Convective Outlook To : wx-storm@lists.illinois.edu From : COD Weather Processor Date : Mon Feb 27 2023 19:41:39 ACUS01 KWNS 271941 SWODY1 SPC AC 271940 Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0140 PM CST Mon Feb 27 2023 Valid 272000Z - 281200Z ....THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS OVER PARTS OF INDIANA...OHIO...AND FAR NORTHERN KENTUCKY... ....SUMMARY... Severe thunderstorms capable of producing a few tornadoes and damaging gusts remain possible across the Ohio Valley today, especially across parts of Indiana and Ohio. ....20Z Update... Little was changed from the previous outlook except to reduce severe probabilities behind the main front, and across central KY where drying is occurring. Otherwise, shear remains strong across the warm sector, which is bounded to the north by a warm front roughly from central OH into northern WV. Temperatures rising into the 60s F with mid 50s F dewpoints may be sufficient to support several supercells with a few tornadoes possible beneath the cold pocket aloft. ...Jewell.. 02/27/2023 ..PREV DISCUSSION... /ISSUED 1026 AM CST Mon Feb 27 2023/ ....Ohio Valley... A compact shortwave trough with an associated pocket of cold mid-level temperatures (around -18 to -20C at 500 mb) will advance quickly east-northeastward over the OH Valley and Great Lakes region today. At the surface, a low will gradually occlude as it develops eastward over northern IL, southern Lower MI, and vicinity through this evening. Pronounced low/mid-level flow strengthens and veers with height per recent area VWPs, with plentiful low-level shear to support updraft rotation. While instability should remain fairly weak owing to modest low-level moisture along/south of a warm front, visible satellite imagery shows some clearing occurring across eastern IL into IN this morning. RAP forecast soundings suggest that as surface temperatures warm into the 60s amid mid to upper 50s dewpoints, resultant 250-600 J/kg MLCAPE should support surface-based convection. A 50-60+ kt low-level jet, with flow quickly veering to southwesterly above that through mid levels, is aiding enlarged hodographs across the gradually destabilizing warm sector, with effective SRH of 200-300+ m2/s2 likely along/south of the surface front. A couple of tornadoes have already occurred this morning associated with a low-topped supercell in east-central IL. As additional low-topped storms develop over the next couple of hours and spread eastward into parts of northern/central IN, threat for a few tornadoes should continue given the plentiful low-level shear. Isolated damaging winds may also occur with any small bowing segments. Sufficient low-level moisture to support surface-based convection will attempt to advance northward into parts of OH this afternoon as well. Some tornado and damaging wind threat should continue across OH if this occurs, as the enhanced wind fields attendant to the low-level jet and mid-level shortwave trough shift quickly eastward across the OH Valley. These low-topped cells will eventually outpace the low-level moisture return and surface-based instability by this evening, with a lessening severe threat with eastward extent into PA/WV. $$ = = = 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) .