Subj : DAY1SVR: Day 1 Convective Outlook To : wx-storm@lists.illinois.edu From : COD Weather Processor Date : Sat Mar 23 2024 12:50:53 ACUS01 KWNS 231250 SWODY1 SPC AC 231249 Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0749 AM CDT Sat Mar 23 2024 Valid 231300Z - 241200Z ....THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS OVER PARTS OF SOUTH FLORIDA AND THE KEYS... ....SUMMARY... Isolated strong to severe thunderstorms may occur today across parts of south Florida and the Keys. ....Synopsis... In mid/upper levels, a series of shortwaves -- including the open- wave remnants of a cyclone now moving toward the Pacific Northwest Coast -- will contribute to development of a large synoptic trough over the West by 12Z tomorrow. Meanwhile, a downstream/southern- stream perturbation -- evident in moisture-channel imagery over the southern Appalachians to the FL Panhandle and central Gulf -- will shift eastward. By 00Z, the trough should extend from the Carolinas and coastal GA south-southwestward across northern FL and the extreme eastern Gulf. By 12Z, the trough should be offshore from the southern Atlantic Coast, including FL. At the surface, 11Z analysis showed a frontal-wave low over northeastern NC in the RDU/RWI area, with cold front across central portions of SC/GA to the west-central FL Panhandle and central Gulf. A prefrontal trough with northwesterly wind shift was drawn across southern GA, the FL coastal bend, and the east-central Gulf. A warm front -- poorly defined due to the presence of convection and dense precip on both sides -- was apparent from the low southeastward over parts of the Outer Banks. The low should move swiftly northeastward today, reaching near Montauk Point around 00Z, with the trailing cold front effectively catching the trough and moving offshore from the remainder of the Atlantic Coast (including FL). ....South FL/Keys... Widely scattered to scattered thunderstorms are possible through midafternoon in the destabilizing, prefrontal warm sector over south FL. The most vigorous cells may produce marginally severe gusts. The prefrontal air mass over the region will remain characterized by surface dewpoints around 68-72 F over most of south FL. Modified RAOBs and forecast soundings suggest this will support around 1000- 1500 J/kg MLCAPE with minimal CINH, and that convection now over parts of south FL already may be surface-based in the recovery zone of warm advection behind the prior night's activity. However, light and variable winds near the surface will become southwesterly to westerly through midday, while flow from just above the surface through 850 mb veers more. Though this will reduce hodograph size markedly, sufficient speed shear will remain to yield effective- shear magnitudes around 45-60 kt. Weak/intermittent supercell characteristics may be noted, while fast cell motions contribute to locally damaging downdrafts. ....Eastern NC... Somewhat organized thunderstorms extend from near HSE south- southwestward over Atlantic waters, moving northeastward. The most- intense activity should remain offshore where low-level instability and deep bulk shear each should be most favorable. Persistent overland precip has minimized buoyancy, and deep shear should continue to diminish as flow aloft weakens with time nearest the trough aloft. Behind the early precip area, some destabilization, related to both warm advection and patchy insolation, is expected diurnally. This may support isolated to widely scattered convection along/ahead of the cold front. However, with the low and associated isallobaric forcing moving quickly away from the region and up the Mid-Atlantic Coast through 18Z, warm-sector flow will veer, further reducing both vertical shear and low-level convergence. As such, unconditional potential appears too low to maintain a severe outlook. ...Edwards/Grams.. 03/23/2024 $$ = = = 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) .