Subj : DAY3SVR: Nws Storm Prediction Center Norman Ok To : wx-storm@lists.illinois.edu From : COD Weather Processor Date : Wed Aug 23 2023 07:20:21 ACUS03 KWNS 230720 SWODY3 SPC AC 230719 Day 3 Convective Outlook NWS Storm Prediction Center Norman OK 0219 AM CDT Wed Aug 23 2023 Valid 251200Z - 261200Z ....THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS FRIDAY AFTERNOON AND EVENING ACROSS PARTS OF SOUTHERN INDIANA...OHIO...PENNSYLVANIA AND NEW JERSEY...MUCH OF CENTRAL AND EASTERN KENTUCKY...WEST VIRGINIA...VIRGINIA...MARYLAND...AND DELAWARE...PARTS OF NORTHERN NORTH CAROLINA AND TENNESSEE...EASTERN MINNESOTA...AND NORTHWESTERN WISCONSIN... ....SUMMARY... Strong thunderstorms may impact parts of the lower Ohio Valley into Mid Atlantic and portions of the Upper Midwest Friday afternoon and evening, accompanied by at least some risk for severe weather. ....Synopsis... Models indicate that large-scale troughing at mid/upper levels will gradually evolve and begin to amplify across the Upper Midwest into the northern Atlantic Seaboard late Friday into Friday night, as a pair of short wave perturbations dig through northwesterly flow. The lead perturbation is forecast to reach the Mid Atlantic vicinity by early Friday, before turning eastward offshore, as the more prominent upstream impulse digs across the Upper Midwest through Great Lakes. In lower levels, a notable cold front may reach the vicinity of the lower Ohio and Missouri Rivers by midday Friday, before continuing into the southern Mid Atlantic coast and Tennessee Valley by 12Z Saturday. A second cold front is forecast to nose eastward and southeastward to the lee of the northern Rockies, through the upper Great Lakes, middle Missouri Valley and central Great Plains by the end of the period. From the Rockies into the Missouri Valley, the advancement of the cooler near surface air will be beneath amplified mid-level ridging, to the north of a still prominent high over the Texas Panhandle vicinity, downstream of large-scale troughing with an embedded low near and offshore of the Pacific coast. Even to the east of the Mississippi Valley, the southward advancement of the leading edge of the cooler air may be maintained to the south of the stronger mid/upper flow. Around the periphery of the southern Great Plains mid-level high, the weakened remnants of Harold may slowly progress northeastward across the Colorado Rockies and adjacent Great Plains, while another easterly wave passes to the south of the lower Texas coast. ....Ohio Valley into Mid Atlantic... Although steeper lapse rates and stronger shear (associated with 30+ kt westerly flow in the 850-700 mb layer) may largely be confined to the lower/mid-levels, the pre-frontal environment may still become conducive to scattered strong thunderstorm development Friday afternoon. Aided by at least moderately large mixed-layer CAPE, potentially damaging wind gusts may be the primary severe threat, associated with localized downbursts and strengthening surface cold pools accompanying upscale growing clusters into Friday evening. ....Upper Midwest... Models suggest that at least modest destabilization is possible in a narrow corridor of stronger heating ahead of the secondary cold front, across parts of southwestern into northeastern Minnesota by late Friday afternoon. Beneath 50+ kt northwesterly mid-level flow and the mid-level cold pool associated with the digging short wave impulse, thermodynamic profiles and shear may become favorable for a few strong storms posing a risk for severe hail and gusty winds. ...Kerr.. 08/23/2023 $$ = = = 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) .