Day 1 Severe Weather Outlook

Valid 311200Z – 011200Z


A few severe storms may occur across parts of south Florida and the
Florida Keys this evening and overnight. Isolated damaging wind
gusts and perhaps a couple of tornadoes should be the main threats.

…South Florida and Florida Keys…
Southwest mid-level flow will remain in place across the eastern
U.S. today as an upper-level trough moves through the southern
Plains. A 70 to 85 kt mid-level jet out ahead of the upper-level
system will move across the northern Gulf of Mexico. At the surface,
a low will move into the northeastern Gulf of Mexico as warm
advection occurs across the Florida Peninsula. Surface dewpoints
will increase in the lower to mid 60s F across south Florida this
afternoon with the moist airmass in place this evening into the
overnight period. In response, instability is forecast to increase
with MLCAPE values across the Florida Keys and south Florida
reaching the 1000 to 1500 J/kg range. The models are in reasonable
agreement with developing thunderstorms along the moist corridor in
the eastern Gulf of Mexico late this afternoon. This convection
should move eastward into south Florida this evening and waves of
convection may affect parts of south Florida through much of the
overnight period. In addition to moderate instability, forecast
soundings at 06Z on Saturday in the Florida Keys show 0-6 km shear
values around 50 kt which should be sufficient for an organized
severe threat. The stronger short line segments could be associated
with isolated damaging wind gusts. In addition, 0-3 km storm
relative helicities are forecast to increase in the 200 to 250 m2/s2
range after midnight which could support a marginal tornado threat
as well.

..Broyles/Bentley.. 01/31/2020


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