Subj : DAY3SVR: Nws Storm Prediction Center Norman Ok To : wx-storm@lists.illinois.edu From : COD Weather Processor Date : Sat Aug 24 2024 07:42:36 ACUS03 KWNS 240742 SWODY3 SPC AC 240741 Day 3 Convective Outlook NWS Storm Prediction Center Norman OK 0241 AM CDT Sat Aug 24 2024 Valid 261200Z - 271200Z ....THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FROM PORTIONS OF SOUTH DAKOTA EASTWARD TO THE WISCONSIN VICINITY... ....SUMMARY... Severe storms are expected to evolve within a zone extending from the northern High Plains eastward to the Wisconsin vicinity, and southward to the southern High Plains during the afternoon and evening Monday. A few severe storms are also expected across the Northeast and Mid-Atlantic region. ....Synopsis... An upper trough over the Intermountain West at the start of the period is forecast to eject northeastward across the High Plains into the north-central U.S. by the second half of the period. This will result in weakening of the persistent upper ridge over the central CONUS. Meanwhile, a weak upper low is forecast to shift south-southeastward across the Northeast/New England through the period. At the surface, a baroclinic zone lying across the north-central U.S. will sharpen and shift southeastward through the second half of the period, as the upper system shifts into/across the northern Plains. This front will likely focus severe storm development during the afternoon and evening hours. ....South Dakota vicinity to the Upper Great Lakes... While timing of the ejection of the upper system into/across the north-central U.S. remains a bit uncertain due to differences in the output from various models, a general consensus that afternoon storm initiation will occur across this region exists, as a very unstable airmass evolves diurnally. With flow forecast to veer/increase with height to southwesterly at 40 to 50 kt, shear will support organized/supercell storms. Coverage through the daylight hours may remain isolated across much of the region however, due to low-level capping. Still, any storms which do develop would be capable of producing large hail and damaging winds. Storm coverage may increase overnight as the trough advances and a southwesterly low-level jet develops, with convection -- and ongoing severe risk, spreading eastward across the Upper Midwest into the Upper Mississippi Valley into early Tuesday morning ....The High Plains... Modest afternoon destabilization forecast across the High Plains from southeastern Montana southward to northeastern New Mexico and the Texas/Oklahoma Panhandles should support isolated storm development. This development will be aided by increasing large-scale ascent associated with the ejection of the upper trough across the High Plains region during the afternoon. While flow aloft will be stronger with northward extent, supporting a few strong/severe storms with damaging wind potential, the very deep afternoon mixed layer farther south (mixed to/above 700 mb) will likely compensate somewhat for the lack of shear. As such, isolated severe gust potential may extend southward into the southern High Plains. ....The Northeast and Mid-Atlantic region... As a weak upper low shifts southeastward across the Northeast, modest afternoon destabilization is expected across portions of the region. While uncertainty regarding ample CAPE development exists, a belt of enhanced northwesterly flow aloft on the southern and western flank of the low will provide sufficient shear for southeastward-moving storms and potentially linear segments/clusters. Presuming at least minimally sufficient afternoon destabilization, stronger storms would pose a risk for damaging gusts locally, into the early evening hours. ...Goss.. 08/24/2024 $$ = = = 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 3.20-Linux * Origin: capitolcityonline.net * Telnet/SSH:2022/HTTP (1:2320/105) .