Subj : DAY2SVR: Nws Storm Prediction Center Norman Ok To : wx-storm@lists.illinois.edu From : COD Weather Processor Date : Mon Nov 20 2023 07:01:42 ACUS02 KWNS 200701 SWODY2 SPC AC 200659 Day 2 Convective Outlook NWS Storm Prediction Center Norman OK 1259 AM CST Mon Nov 20 2023 Valid 211200Z - 221200Z ....THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS A SMALL PART OF SOUTH AL AND THE FL PANHANDLE... ....SUMMARY... A couple tornadoes are possible across parts of south Alabama into the Florida Panhandle, mainly during the morning and early afternoon. Locally damaging winds and perhaps a couple brief tornadoes will also be possible from Georgia into the Carolinas Tuesday afternoon into Tuesday night. ....Synopsis... A vigorous mid/upper-level low is forecast to evolve into an open wave on Tuesday as it moves toward the lower Great Lakes and Northeast through the day. The related surface cyclone will take a similar track, with some weakening expected as it becomes increasingly displaced from the effective warm sector. A trailing cold front will continue to move through parts of the Southeast. One or more surface waves may develop along the effective warm front, with most guidance depicting consolidation of a surface cyclone near or off of the Mid Atlantic coast by Wednesday morning. Guidance continues to vary substantially with regard to large-scale trough evolution in the wake of the departing midlevel low, with the GFS (and now the 20/00Z ECMWF) continuing to amplify a shortwave near the Ozarks/lower MS Valley vicinity, while other guidance maintains a broad positively tilted trough that gradually moves eastward toward the Atlantic Coast. ....Parts of AL/GA and the FL Panhandle... While the primary surface cyclone will continue moving away from the region on Tuesday, convection will likely persist through the day within a confluent regime along/ahead of the front across parts of AL and FL Panhandle, and eventually move into parts of GA. Generally weak instability (with MLCAPE generally less than 500 J/kg away from the immediate coast) may tend to limit storm intensity, but favorable moisture and deep-layer shear will continue to support the potential for at least transient supercell structures. 0-1 km SRH generally in the 150-250 m2/s2 range will support some tornado threat where sufficient destabilization can occur. The threat may peak early in the day across south AL and the FL Panhandle, in association with any supercells that develop during the D1/Monday period and persist into Tuesday morning. A small Slight Risk has been included across this area, as a continuation of the threat from late on D1/Monday. Some threat for locally damaging gusts and/or a brief tornado may persist into the afternoon across parts of GA, in areas where modest diurnal heating can augment generally weak instability. ....Carolinas... A warm front is forecast to move northward across the Carolinas during the day, accompanied by low 60s F dewpoints. While wind profiles will become increasingly favorable for organized convection, instability is expected to remain very weak through the afternoon, due to weak lapse rates and rather widespread cloudiness and precipitation. There is some potential for an organized frontal band to develop and move eastward, which could pose a damaging-wind threat given the expected strength of low-level flow. A conditional Marginal Risk has been included for this threat, though the areal coverage of the convectively enhanced gust threat remains uncertain, due to diminishing instability with northward extent. Strong low-level shear could also support a brief tornado threat if pockets of somewhat greater instability can materialize. Somewhat richer moisture (with dewpoints in the mid 60s F) may advect northward into eastern NC Tuesday evening into the overnight, as low-level flow veers and strengthens some in response to the deepening cyclone near the Mid Atlantic coast. Some uptick in the tornado/wind threat is possible over eastern NC and the Outer Banks as this occurs, though uncertainty remains high regarding evolution of the upper trough (described above) and strength of large-scale ascent across the region during the overnight period. ...Dean.. 11/20/2023 $$ = = = 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) .