Day 1 Severe Weather Outlook

Valid 221630Z – 231200Z

…THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS THIS AFTERNOON
ACROSS THE FL KEYS AND TONIGHT ACROSS SOUTHEAST FL…

…SUMMARY…
A tornado or two and isolated damaging winds will be possible later
this afternoon across the Florida Keys and overnight across
southeast Florida.

…FL Keys this afternoon into southeast FL tonight…
A midlevel low over the lower MS Valley will move slowly
east-southeastward to the northeast Gulf coast by early Monday. An
associated surface low will move inland over the FL Panhandle and
continue generally eastward near the FL/GA border to the Atlantic
coast by Monday morning, as a trailing cold front progresses
eastward across the FL peninsula. Within the warm sector of the
cyclone, regional 12z soundings revealed poor lapse rates aloft and
moist profiles across central/north FL, which will limit the
potential for severe storms this far north. The richest low-level
moisture (low 70s boundary-layer dewpoints) and resultant buoyancy
will overspread the FL Keys this afternoon and southeast FL tonight.

Modest forcing for ascent and the moist profiles will favor a mix of
cells and clusters as the primary convective modes. MLCAPE of
500-1000 J/kg, with effective bulk shear of 40 kt or greater and 0-1
km SRH of 150-200 m2/s2, will support a threat for embedded
supercells capable of producing a tornado or two and isolated
damaging winds. Small supercells in the warm advection regime will
pose a marginal tornado/damaging wind threat through early-mid
afternoon near Key West. The primary severe threat is expected this
evening across the Keys and into southeast FL overnight, immediately
in advance of the surface cold front.

..Thompson/Squitieri.. 12/22/2019

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