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 201715
Day 2 Convective Outlook
NWS Storm Prediction Center Norman OK
1115 AM CST Mon Dec 20 2021
Valid 211200Z - 221200Z
...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF
THE FLORIDA PENINSULA...
...SUMMARY...
Isolated strong to severe thunderstorms may occur across parts of
the Florida Peninsula Tuesday morning and afternoon.
...Synopsis...
A shortwave trough will continue to move eastward across the
Southeast on Tuesday. A related surface low should be located over
the eastern Gulf of Mexico at the start of the period. This low is
forecast to develop generally east-northeastward across parts of the
northern/central FL Peninsula through the day, eventually advancing
over the western Atlantic by Tuesday evening in tandem with the
upper trough. A cold front attendant to the surface low will sweep
southeastward across the FL Peninsula through the period.
...Florida Peninsula...
Rich low-level moisture characterized by at least upper 60s surface
dewpoints should attempt to return northward across much of the FL
Peninsula ahead of the approaching upper trough and surface low. A
fairly robust low-level jet (35-45 kt) aiding the low-level moisture
return will be present across this region Tuesday morning. Still,
mid-level lapse rates are forecast to remain rather poor, and
combined with limited diurnal heating due to widespread cloud cover,
MLCAPE should remain generally weak. There also appears to be some
potential for fairly widespread precipitation to be ongoing Tuesday
morning across the FL Peninsula in the low-level warm/moist
advection regime, which may further hamper the development of more
robust instability.
Most guidance suggests that a band of storms will likely be
approaching the western FL Peninsula Tuesday morning. There is still
a fair amount of variability regarding the intensity of these storms
as they approach the coast and subsequently move inland. Various NAM
forecast soundings across the southern/central FL Peninsula from
12-18Z Tuesday show enough boundary-layer instability to support
surface-based storms, and sufficient deep-layer shear (around 30-40
kt) for organized updrafts. There may be a small window for a brief
tornado or two mainly Tuesday morning, as low-level shear will be
maximized while the low-level jet shifts eastward. Otherwise,
isolated strong to damaging winds may occur with any storms that can
maintain their intensity over land as they move from the eastern
Gulf of Mexico across the FL Peninsula. At this point, it appears
that the weak instability forecast will probably tend to limit the
overall severe threat. Accordingly, a Marginal Risk has been
maintained with only minor changes.
..Gleason.. 12/20/2021
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