SPC AC 241226
Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0626 AM CST Fri Nov 24 2017
Valid 241300Z - 251200Z
...NO SEVERE THUNDERSTORM AREAS FORECAST...
Isolated thunderstorms are possible across portions of the Florida
Peninsula and Keys.
In mid/upper levels, mean troughing over the eastern U.S. will
persist. Meanwhile western ridging will amplify again, following
the departure of a positively tilted shortwave now over parts of
MT/ID/OR. A well-defined/southern-stream shortwave trough -- now
evident in moisture-channel imagery over the extreme eastern Gulf of
Mexico -- will cross FL through the daytime hours.
At the surface, an elongated frontal-wave low offshore from the FL
Atlantic coast is expected to consolidate and ripple northeastward
along the boundary today, while the trailing cold front proceeds
southeastward down the remainder of the peninsula and across the
Keys by late this evening and overnight.
Thunder coverage today over land looks to be much more limited than
evident in the previous outlook. Showers and isolated thunderstorms
are possible primarily over southeastern areas into early afternoon,
as boundary-layer heating/mixing reduces MLCINH and weak convergence
supports development, amidst favorable low-level moisture. Modified
12Z MFL RAOB and model forecast soundings suggest 800-1200 J/kg
MLCAPE is possible. Lack of more robust deep shear, lift and lapse
rates indicates minimal severe potential. As the afternoon
progresses, isallobaric forcing related to offshore Atlantic
cyclogenesis will veer prefrontal surface winds and reduce
convergence. At the same time, large-scale subsidence behind the
aforementioned southern-stream perturbation, as evident in
moisture-channel drying, will spread eastward across the region,
further disfavoring additional/substantial convective potential.
NOTE: THE NEXT DAY 1 OUTLOOK IS SCHEDULED BY 1630Z