Subj : DAY1SVR: Day 1 Convective Outlook To : wx-storm@lists.illinois.edu From : COD Weather Processor Date : Wed Sep 13 2023 05:42:49 ACUS01 KWNS 130542 SWODY1 SPC AC 130541 Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 1241 AM CDT Wed Sep 13 2023 Valid 131200Z - 141200Z ....THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF SOUTHERN NEW ENGLAND...SOUTHEAST ATLANTIC COAST...AND MUCH OF THE SOUTHWESTERN US... ....SUMMARY... Marginally severe thunderstorms are possible in parts of the southwestern U.S./southern high Plains, southern New England, and the southeast Atlantic Coast on Wednesday. ....Discussion... Large-scale pattern will continue to favor deep convection across southern portions of the CONUS as the southern branch of a split flow regime provides sufficient shear for organized updrafts where buoyancy is adequate. Organized convection may also occur early in the period over southern New England ahead of a strong short-wave trough. ....Southern New England... Weak midlevel height falls will spread across the northeastern US ahead of a strong short-wave trough that is currently advancing east across the Great Lakes. Low-level warm advection is expected to increase across southern New England early in the period in response to this approaching short wave. Early this morning, leading edge of stronger low-level warm advection is contributing to scattered convection across the Mid-Atlantic. Models suggest a modest LLJ will translate across the Delmarva into western Long Island/southern CT early in the period. While poor lapse rates will be noted across this region, strong shear may support gusty winds with the strongest convection, or perhaps even a brief tornado. Primary severe threat will be during the first half of the period. ....Carolinas... Boundary-layer warming will steepen low-level lapse rates across the coastal Carolinas into southeast GA by late morning. As a result, convective temperatures should be breached by 17z within a westerly flow regime characterized by roughly 20kt surface-6km bulk shear. Gusty winds may accompany the more robust updrafts before they progress offshore. ....Southwestern US... Water-vapor imagery suggests a weak short-wave trough is progressing across the lower CO River Valley. Another weak disturbance is advancing across western NM. Each of these features will encourage deep convection later today as boundary layer warms. 500mb flow is on the order of 30kt within the southern branch of the westerlies and this is more than adequate for updraft organization given the modest lapse rate environment. Forecast soundings suggest minimal CINH will be present across this region and large-scale ascent ahead of each short wave should assist deep convection. Gusty winds/hail may be noted with the strongest storms. Some supercell threat exists but multi-cell updrafts/clusters may also be observed. ...Darrow/Squitieri.. 09/13/2023 $$ = = = 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) .