Subj : DAY1SVR: Day 1 Convective Outlook To : wx-storm@lists.illinois.edu From : COD Weather Processor Date : Wed Feb 28 2024 00:57:13 ACUS01 KWNS 280057 SWODY1 SPC AC 280055 Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0655 PM CST Tue Feb 27 2024 Valid 280100Z - 281200Z ....THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS OVER NORTHERN ILLINOIS AND NORTHWEST INDIANA...AND FROM SOUTHEAST MISSOURI ACROSS MUCH OF THE OHIO VALLEY... ....SUMMARY... Severe thunderstorms producing tornadoes, damaging hail and wind remain likely over parts of northern Illinois this evening, and through tonight into parts of the Ohio Valley. ....Northern Illinois and Vicinity... Supercells, some tornadic, have developed near the surface low just ahead of the cold front over northern IL, and along the east-west boundary which separates the greater theta-e to the south. Very steep lapse rates aloft exist across the warm sector, where mid to upper 50s F dewpoints are contributing to MUCAPE to 2000 J/kg. As the surface low continues to deepen, the low-level jet will strengthen across much of eastern IL, IN, and points south, enhancing shear. As such, hodograph enlargement should support a continued, and possibly increasing, significant-tornado threat across parts of northern IL and eventually northwest IN later this evening. The tornado threat may extend into southern Lower MI as well, coincident with the surface low. For more information, see mesoscale discussion 166. ....Southern IL and IN across much of the OH Valley Tonight... A dryline currently extends from central IL southwestward into northern AR, within the low-level lapse rate plume. Although farther south from the surface low, midlevel temperatures remain quite cool, resulting in steep lapse rates. In addition, boundary-layer theta-e remains robust with lower 60 F dewpoints, contributing to around 1000 J/kg MLCAPE. Several more hours of potential boundary-layer moistening will occur ahead of the cold front from AR toward the lower OH Valley tonight, as 850 mb winds increase to 60 kt. Although low-level winds may veer, forecast storm motions are expected to be over 50 kt which may allow for storms to remain just on or even ahead of the cold front. And, effective SRH is forecast to remain over 300 m2/s2. The end result will be storms focused along the front, possibly with linear segments or broken with discrete supercells, with tornado, damaging-wind, and hail potential. Strong-tornado potential will exist with any activity remaining along or just ahead of the cold front. For more information in the near term, see mesoscale discussion 165. ...Jewell.. 02/28/2024 $$ = = = 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) .