Subj : DAY2SVR: Nws Storm Prediction Center Norman Ok To : wx-storm@lists.illinois.edu From : COD Weather Processor Date : Tue Apr 04 2023 05:35:29 ACUS02 KWNS 040535 SWODY2 SPC AC 040533 Day 2 Convective Outlook NWS Storm Prediction Center Norman OK 1233 AM CDT Tue Apr 04 2023 Valid 051200Z - 061200Z ....THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS WEDNESDAY ACROSS MUCH OF THE LOWER GREAT LAKES REGION AND OHIO VALLEY... ....SUMMARY... Scattered severe storms posing a risk for strong tornadoes and large hail are expected in a corridor across eastern Illinois through Lower Michigan Wednesday, with organizing clusters or lines of storms accompanied by potentially damaging wind gusts, and perhaps a couple of tornadoes, across the Ohio Valley vicinity. ....Synopsis... Within the more amplified branch of split flow emanating from the mid-latitude Pacific, the center of a broad and deep, occluding cyclone is forecast to migrate across and northeast of the Lake Superior vicinity before beginning to weaken Wednesday through Wednesday night. As this occurs, it appears that mid-level ridging centered along an axis across the Yucatan Peninsula into western Atlantic will remain a prominent influence across much of the Southeast, while short wave ridging also overspreads the Northeast and Canadian Maritimes. Models indicate a corridor of deepening boundary-layer moisture overspreading the Ozark Plateau and middle Mississippi Valley, into the Lake Michigan vicinity, by early Wednesday. This is forecast to spread across much of the lower Great Lakes and Ohio Valley, ahead of the cold front trailing the cyclone, while the trailing flank of the front stalls across the lower Mississippi Valley into northwestern Gulf coastal plain, beneath the northwestern periphery of the mid-level ridging. ....Illinois through lower Michigan... Beneath a dry slot overspreading the region, south and east of an intensifying cyclonic mid-level jet (in excess of 120 kt around 500 mb), surface heating and steepening mid-level lapse rates are expected to contribute to sufficient destabilization for intensifying supercells. This may commence in a pre-frontal corridor as early as mid Wednesday morning across parts of central into northeastern Illinois, before developing into/across Lower Michigan and parts of adjacent northern Indiana and northwestern Ohio through late afternoon. It remains unclear what effect the cooler marine layer from Lake Michigan has on adjacent coastal areas, particularly into portions of western Michigan. However, Rapid Refresh forecast soundings, in particular, indicate a rather potent thermodynamic and kinematic environment supportive of strong tornadoes. This includes sizable CAPE, strong deep-layer shear and large clockwise-curved low-level hodographs. It is possible that severe weather probabilities could still be increased further in later outlooks for this period. ....Ohio Valley... To the south of the dry slot (within a plume of seasonably high precipitable water, and generally aligned with a belt of 40-70 kt west-southwesterly flow in the 850-500 mb layer), models indicate the potential for more widespread convection, organizing into clusters or lines while overspreading much of the Ohio Valley through the day. While lapse rates may not be particularly steep, given the strong flow, with at least modest CAPE and the increased potential for heavy precipitation loading and organizing convection, the environment probably will become conducive to damaging surface gusts, in addition to some risk for tornadoes. ....Lower Mississippi Valley... South of the Ohio Valley, weakening low-level flow seems likely to result in more limited severe weather potential as the cold front gradually stalls. While a corridor of sizable pre-frontal CAPE beneath strong deep-layer shear may provide a window for strong/severe storm development, this may be limited as convection tends to train above congealing outflow and/or the front. ...Kerr.. 04/04/2023 $$ = = = 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) .