Probability of damaging thunderstorm winds or wind gusts of 50 knots or higher within 25 miles of a point. Hatched Area: 10% of greater probability of wind gusts 65 knots or greater within 25 miles of a point.
Probability of hail 1" or larger within 25 miles of a point. Hatched Area: 10% or greater probability of hail 2" or larger within 25 miles of a point.
Day 2 Hail Risk
Area (sq. mi.)
Area Pop.
Some Larger Population Centers in Risk Area
No Risk Areas Forecast
SPC AC 200657
Day 2 Convective Outlook
NWS Storm Prediction Center Norman OK
1257 AM CST Mon Dec 20 2021
Valid 211200Z - 221200Z
...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS FOR PORTIONS OF
THE FLORIDA PENINSULA...
...SUMMARY...
A couple of strong to severe thunderstorms are possible across the
Florida Peninsula on Tuesday morning/afternoon.
...Synopsis...
Though a relatively cool and stable airmass will limit thunderstorm
development across much of the CONUS tomorrow, organized
thunderstorm potential is expected across the FL peninsula with the
approach of a mid-level trough and associated surface low.
Marginally buoyant low-level air will advect northward as the
surface low approaches the peninsula, with deep-layer ascent ahead
of the mid-level trough encouraging thunderstorm development
tomorrow morning into the afternoon. Enough vertical wind shear will
be in place in close proximity to the surface low to encourage
thunderstorm organization, with isolated strong to severe
thunderstorms possible.
...Florida Peninsula...
Uncertainty remains regarding placement and timing of the upper
trough and associated surface low given considerable variance in
multiple guidance members. There is some guidance consensus that the
surface low and associated deep-layer ascent will approach the FL
Peninsula during the morning/early afternoon hours, and that at
least isolated organized thunderstorms are expected to approach the
western FL coastline. 50+ kts of mid-level westerly flow atop a 30+
kt southwesterly LLJ is expected to contribute to 35-45 kts of
effective bulk shear, with over 45 degrees of veering surface-700 mb
winds supporting 200 m2/s2 effective SRH, particularly in central
FL, where the surface low is expected to track. The more aggressive
guidance depicts 6-6.5 C/km low and mid-level lapse rates
overspreading low to mid 60s F dewpoints and contributing to MLCAPE
exceeding 500 J/kg across the FL peninsula by afternoon. However,
several convection and non-convection allowing guidance members
depict widespread cloud cover and heavier precipitation preceding
the arrival of the surface low, potentially further limiting
instability. As such, a Category 1/Marginal risk has been maintained
for the threat of isolated damaging gusts across the peninsula, and
the risk of a brief tornado in proximity to the surface low tomorrow
afternoon.
..Squitieri.. 12/20/2021
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NOTE: THE NEXT DAY 2 OUTLOOK IS SCHEDULED BY 1730Z
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