Subj : DAY2SVR: Marginal Risk To : ALL From : Mike Powell Date : Tue Sep 12 2023 20:26:00 ACUS02 KWNS 121729 SWODY2 SPC AC 121727 Day 2 Convective Outlook NWS Storm Prediction Center Norman OK 1227 PM CDT Tue Sep 12 2023 Valid 131200Z - 141200Z ....THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS FOR PARTS OF SOUTHERN NEW ENGLAND...COASTAL CAROLINAS...SOUTHERN HIGH PLAINS... ....SUMMARY... Marginally severe thunderstorms are possible in parts of the southern High Plains, southern New England, and the Carolinas on Wednesday. ....Synopsis... An upper-level trough will move from the Great Lakes/Ohio Valley toward New England on Wednesday. Multiple vorticity maxima will be embedded within the midlevel southwesterly flow ahead of this trough. At the surface, a cold front will move across parts of the Northeast and Mid Atlantic into the southern Appalachians, with a weak frontal wave potentially moving from the Mid Atlantic into New England through the day. Farther west, a broad upper-level trough will remain in place across parts of the western/central CONUS, with one notable shortwave trough expected to move eastward from the southern Rockies into the southern Plains. ....Northern NJ/Southeast NY into southern New England... A band of convection will likely be ongoing at the start of the forecast period somewhere across southeast NY/northern NJ into western parts of southern New England, aided by low-level warm advection and midlevel vorticity maxima ejecting northeastward ahead of the primary upper trough. Instability will generally remain weak, but moderate deep-layer shear, favorable moisture, and some enhancement of low-level shear/SRH within the warm-advection regime may support transient rotating cells capable of locally damaging gusts and/or a brief tornado. The primary threat may reside with the initial cluster of convection as it moves eastward across southern New England, though some redevelopment will be possible its wake, depending on timing of early convection and extent of destabilization in its wake. ....Coastal Carolina vicinity... In advance of the large-scale trough to the north, one or more weak midlevel vorticity maxima may move across parts of the Carolinas Wednesday. These may aid in scattered afternoon thunderstorm development within a warm, moist, and moderately unstable environment during the afternoon. Modest westerly midlevel flow will support effective shear of 25-30 kt, sufficient for some storm organization, and a few semi-organized cells/clusters will be possible. A Marginal Risk has been added for parts of near-coastal SC and southern NC, where the best overlap of instability, shear, and storm coverage is currently anticipated. ....Southern High Plains vicinity... Scattered thunderstorms are expected from the southern Rockies into the High Plains Wednesday afternoon/evening, as a midlevel shortwave trough traverses the region. Weak to moderate buoyancy and sufficient deep-layer shear will support a few organized cells/clusters capable of producing localized hail and severe gusts. ....Southeast AZ into southwest NM... Scattered thunderstorm development will again be possible across parts of southern AZ into southwest NM on Wednesday. Moisture/instability may be somewhat weaker than D1/Tuesday, though deep-layer shear will remain marginally sufficient for a few semi-organized storms. Depending on the extent of D1 convection across the region and its potential impact on D2 destabilization, severe probabilities may eventually be needed. ...Dean.. 09/12/2023 $$ --- * SLMR 2.1a * You radiate cold shafts of broken glass! * Origin: Ilink: CCO - capitolcityonline.net (454:1/105) .