Subj : DAY3SVR: Nws Storm Prediction Center Norman Ok To : wx-storm@lists.illinois.edu From : COD Weather Processor Date : Thu Jul 27 2023 07:28:39 ACUS03 KWNS 270728 SWODY3 SPC AC 270727 Day 3 Convective Outlook NWS Storm Prediction Center Norman OK 0227 AM CDT Thu Jul 27 2023 Valid 291200Z - 301200Z ....THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS SOUTHERN NEW ENGLAND AND MID-ATLANTIC STATES INTO THE MIDWEST...NORTH-CENTRAL GREAT PLAINS... ....SUMMARY... Isolated severe thunderstorms are possible from parts of the Northeast and Mid-Atlantic states into the Midwest on Saturday. Damaging gusts are the primary hazard. Isolated severe storms are also possible over the north-central Great Plains late Saturday into Saturday night. ....Synopsis... A mid-level high will remain over the Sangre de Cristos. A mid-level trough will move little to the west of the Pacific Northwest coast. Downstream over the northern Rockies, a ridge will be west of a belt of moderate west-northwest flow over the north-central U.S. Farther east, broad cyclonic mid-level flow will reside over the Mid-Atlantic states and Northeast. ....Mid MS Valley east into the Mid-Atlantic states into southern New England... Widely scattered showers/thunderstorms will likely be ongoing across parts of the Northeast near/behind a cold front forecast to push east of the coast during the day. The trailing portion of the boundary will extend from the southern Great Lakes westward into the central Great Plains and become more diffuse with westward extent. Strong heating south of the boundary (especially over the OH Valley) will lead to moderate to strong instability developing by early afternoon. Models indicate a series of weak, embedded mid-level impulses will move through parts of the southern Great Lakes into the Northeast. Convective coverage will probably focus near these weak forcing mechanisms during the afternoon/early evening. Several clusters will likely evolve during the afternoon from parts of the Northeast across the central Appalachians and westward into the mid MS Valley. The stronger storms will be capable of isolated damaging gusts. Due to appreciable uncertainty, it is too early to ascertain whether a mesoscale corridor within the broader Marginal Risk will need higher severe probabilities. Will defer this decision to later outlooks. ....Black Hills and north-central Great Plains... The northeast periphery of steep 700-500mb lapse rates will extend from MT, which will be underneath the mid-level ridge, to areas farther southeast over the central Great Plains. The westward portion of a frontal zone will become draped across the central Great Plains arching northwest to near the Black Hills/eastern WY. Relatively moist low levels (low 50s surface dewpoints within an 850mb moist plume) beneath steep lapse rates near the Black Hills, will support thunderstorm development during the afternoon. The initial isolated storm activity over the High Plains/Black Hills will probably increase in coverage over SD/NE during the evening and into the overnight in the form of a thunderstorm cluster. Isolated severe gusts/large hail will be possible with the stronger storms. ...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) .