Subj : DAY1SVR: Day 1 Convective Outlook To : wx-storm@lists.illinois.edu From : COD Weather Processor Date : Sat Dec 31 2022 19:54:20 ACUS01 KWNS 311954 SWODY1 SPC AC 311952 Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0152 PM CST Sat Dec 31 2022 Valid 312000Z - 011200Z ....NO SEVERE THUNDERSTORM AREAS FORECAST... ....SUMMARY... The potential for organized severe thunderstorms this afternoon and evening appears to have diminished. ....20Z Update... The Marginal Risk across parts of the Southeast has been removed. Confidence remains low that robust convection will develop this afternoon from parts of north FL into southern GA and coastal SC, as low-level convergence remains weak, and the better forcing associated with a mid-level shortwave trough gradually shifts into the Mid-Atlantic. A chance for a strong thunderstorm or two may exist farther north into eastern NC and perhaps far southeastern VA, where a moist low-level airmass is in place and some daytime heating has occurred. But, the potential for organized severe thunderstorms should be limited by the presence of weak instability and poor lapse rates. Finally, strong thunderstorms are ongoing this afternoon over the eastern Gulf of Mexico to the west-southwest of Tampa Bay FL. Current expectations are for this convection to gradually weaken as it approaches land over the next few hours. ...Gleason.. 12/31/2022 ..PREV DISCUSSION... /ISSUED 1027 AM CST Sat Dec 31 2022/ ....Synopsis... A broad large-scale trough over the MS Valley will deamplify as it advances slowly east-northeastward through the period. Within the base of the trough, a shortwave impulse (evident in water vapor imagery) will lift northeastward from the Lower MS/TN Valleys through the Appalachians -- emerging off the New England coast by the end of the period. In the low-levels, a weak quasi-stationary baroclinic zone will remain draped from the central Gulf Coast northeastward toward the Mid-Atlantic. While the mass response at the surface (accompanying the midlevel impulse) will not be particularly strong -- characterized by weak/gradually veering surface winds across the warm/moist sector -- strengthening unidirectional southwesterly flow with height and a northeastward-advancing low-level jet will provide sufficient deep-layer shear for a few organized storms across parts of the Southeast (with more conditional potential into the Mid-Atlantic). ....FL Panhandle into southeastern SC... Low-level confluence (albeit weak) is gradually increasing over the Southeast in the vicinity of a strengthening low-level jet, which combined with glancing large-scale ascent accompanying the midlevel impulse should favor an uptick in thunderstorm development this afternoon. While widespread cloud coverage and elevated showers over the area will limit diurnal destabilization, deep boundary-layer moisture (with middle/upper 60s dewpoints) should support isolated surface-based storms focused along the confluence axis. Surface-based storms will be most likely over areas that can warm into the lower 70s this afternoon. While poor midlevel lapse rates/weak buoyancy may limit convective intensity, any storms that become surface-based could be loosely organized given 40-50 kt of effective shear (characterized by a long/straight hodograph). Locally damaging gusts will be the main concern with this activity -- especially with any constructive cell mergers/local clustering amid minimal CINH -- though a brief/weak tornado cannot be ruled out with any sustained supercell structures. ....Mid-Atlantic... A more conditional severe risk could spread northeastward into the Mid-Atlantic this afternoon, where strong/mainly unidirectional deep-layer shear will develop amid middle/upper 60s dewpoints. However, lingering stable layers above the boundary layer and generally weak forcing limits confidence in robust storm development over this area -- precluding severe probabilities at this time. $$ = = = 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) .