Subj : DAY1SVR: Day 1 Convective Outlook To : wx-storm@lists.illinois.edu From : COD Weather Processor Date : Thu Dec 15 2022 12:43:30 ACUS01 KWNS 151243 SWODY1 SPC AC 151241 Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0641 AM CST Thu Dec 15 2022 Valid 151300Z - 161200Z ....THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS OVER CENTRAL FLORIDA AND IMMEDIATE COASTAL GEORGIA/SOUTH CAROLINA... ....SUMMARY... A few tornadoes and scattered damaging thunderstorm winds will be possible today, mainly over parts of the Florida Peninsula. ....Synopsis... A large mid/upper-level cyclone -- initially centered over northwestern IA, covers much of the CONUS from the Rockies to the Appalachians. The center should redevelop northward over MN toward a strong, orbiting vorticity max pivoting into that region. A narrow, 500-mb vorticity banner - corresponding well to the leading edge of a large dry slot in moisture-channel imagery -- is apparent from the western Carolinas across the FL coastal bend to the eastern Gulf. This feature corresponds well to a swath of isolated to scattered convection across GA, northwestern FL and the eastern Gulf, and is located near the cold front. At 11Z, the cold front was analyzed from a low over northwestern GA across the AAF area, southwestward over central Gulf. A synoptic warm front extended eastward from the low across south-central SC, to just offshore southeastern NC. A longstanding warm/marine front -- separating optimally modified, richly moist Gulf air from residual lower-theta-e FL Peninsula trajectories, was roughly along the west coast of FL and extended north-northwestward into southwestern GA, where it became diffuse in a large area of rain and embedded thunderstorms. The FL portion of this boundary should become diffuse today as warm advection, moisture transport, and diurnal diabatic heating occur inland. ....Southeast... Scattered thunderstorms, in a band just ahead of the cold front, and isolated supercells preceding the front -- may pose a threat for damaging gusts and a few tornadoes through early/mid afternoon -- mainly over FL. The threat becomes more conditional/isolated northward into GA/Carolinas, where instability will be weaker, except perhaps a narrow near-coastal area potentially intruded by a favorable Atlantic boundary layer. The air mass across central FL will destabilize the most favorably today, while buoyancy diminishes northward into GA, amidst precip and residual trajectories arising overland, east of the decaying marine front, and passing through prefrontal precip. Though modest mid/upper-level lapse rates are forecast, the advective and adiabatic increases in near-surface theta-e should support minimally inhibited MLCAPE near 1000 J/kg from late morning through the afternoon across central FL, ahead of the cold front and main convective band. Meanwhile, despite the lack of substantial height falls and the great distance of the synoptic-cyclone core, flow aloft will strengthen over the region until about 00Z. This will occur as the southern rim of broad, 250-500-mb jet cores shift eastward from the northeastern Gulf and across AL/GA. Favorable deep shear for supercells accordingly will be maintained, with forecast soundings reasonably showing effective-shear magnitudes of 35-40 kt over southern parts of central FL, and 50 kt over the weakly unstable (at best) areas in northern FL and GA. Boundary-layer winds will continue to support favorable hodographs through early/mid afternoon. Then, overall weakening and veering of low-level flow will lead to: 1. Shrinking of hodographs with related weakening of low-level SRH/shear, and 2. Decreasing convergence along earlier frontal/prefrontal convective lift zones. Between those factors and weakening instability this evening, severe potential should diminish considerably from late afternoon through evening over southwest/south-central FL. ...Edwards/Leitman.. 12/15/2022 $$ = = = 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) .