Subj : DAY2SVR: Nws Storm Prediction Center Norman Ok To : wx-storm@lists.illinois.edu From : COD Weather Processor Date : Thu Jul 27 2023 06:01:36 ACUS02 KWNS 270601 SWODY2 SPC AC 270559 Day 2 Convective Outlook NWS Storm Prediction Center Norman OK 1259 AM CDT Thu Jul 27 2023 Valid 281200Z - 291200Z ....THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FROM IOWA INTO THE SOUTHERN GREAT LAKES... ....SUMMARY... Widely scattered severe thunderstorms are possible on Thursday and Thursday night across a large portion of the Midwest. ....Synopsis... A flattened mid-level anticyclone will continue to be centered over southern states on Friday. A belt of moderate westerlies will extend from the northern Rockies eastward across the north-central U.S. and into the Northeast. A mid-level shortwave trough and associated speed max will quickly move from near Lake Superior east to the St. Lawrence Seaway. A low-amplitude disturbance will move east-southeast from the Dakotas into the central Great Lakes by the mid evening. A cool front will push southward across the upper MS Valley and portions of the Great Lakes mainly late Friday into Friday night. ....Great Lakes across the Midwest and Black Hills... A residual west-east frontal zone will be draped from near the Black Hills to the central Great Lakes during the morning. A very moist, capped, and destabilizing airmass will be located south of the frontal zone where 70s dewpoints will be common across IA eastward into Lower MI. Given the weakly forced setup, the latest convection-allowing model guidance shows large spread in the timing/placement of a cluster/band of storms from IA and eventually into the southern Great Lakes. Nonetheless, a reservoir of 2000-4000 J/kg MLCAPE will develop from the Dakotas into the southern Great Lakes during the day. It seems probable at least a thunderstorm cluster will develop near the front to the northeast of a weak area of lower pressure (located near the NE/IA border) during the late afternoon. Once storms develop, the magnitude of PW/buoyancy will favor organizing cold pools with an increasing damaging-wind threat. A severe risk will probably continue into the late night aided in part by a strengthening west-southwesterly LLJ during the evening across the southwest Great Lakes. ....Northern Rockies... Isolated to widely scattered diurnal thunderstorms are possible Friday in association with a weak mid-level disturbance forecast to move from CA/NV into the northern Rockies. Steep low- to mid-level lapse rates and sufficient mid-level flow will aid in some storm organization. Isolated severe gusts and perhaps marginally severe hail are possible with the stronger storms. ....Northern Maine... Strong westerly mid to high-level flow accompanying the aforementioned speed max will overspread the region during the day. It appears at least marginal destabilization will occur with surface dewpoints well into the 60s. A band of storms along a frontal zone will probably push eastward into Maine during the afternoon/early evening. Isolated severe gusts are the primary hazard. ...Smith.. 07/27/2023 $$ = = = 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) .