Day 1 Severe Weather Outlook

Valid 292000Z – 301200Z

…THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS THE FL
KEYS AND FAR SOUTH FL…

…SUMMARY…
A severe thunderstorm or two are possible across the Florida Keys
and the extreme southern Florida Peninsula between about 8 PM to 1
AM EST.

…20Z Update…
No changes have been made to the Marginal Risk across the FL Keys
and vicinity. A weak surface boundary evident on visible satellite
over the FL Straits continues to make slow northward progress this
afternoon as a broad/weak low consolidates over the eastern Gulf.
Surface winds have also recently turned to southeasterly along the
Lower/Middle Keys, with surface dewpoints increasing into the mid to
upper 60s.

There is some concern that a lead wave of storms presently about 150
miles west to 230 miles west-southwest of Key West FL may hamper the
northward advance of the surface boundary through the remainder of
the afternoon into the early evening. Still, there appears to be
enough potential for isolated severe storms later this evening and
into the early overnight hours to maintain the Marginal Risk for
this area.

Otherwise, only minor changes have been made to the general
thunderstorm areas across the central Gulf Coast and FL based on
latest observational and short-term model trends.

..Gleason.. 01/29/2020

.PREV DISCUSSION… /ISSUED 1008 AM CST Wed Jan 29 2020/

…FL Keys vicinity…
A shortwave trough over the central Gulf Coast will translate east
off the South Atlantic Coast by early Thursday. Attendant surface
cyclone near the mouth of the MS River should weaken as it
approaches the Fort Myers area while downstream cyclogenesis occurs
in the Atlantic just east of the Space/First Coasts. A residual
front across the FL Straits into the southern Gulf should advance
northeast as low-level southwesterlies strengthen this evening.
Guidance differs on the degree of moistening, with the 14Z RAP
notably aggressive, especially across the southern peninsula. The
opportunity for more substantial moistening and resultant buoyancy
will probably remain confined to the Keys into perhaps the far
southern peninsula.

The RAP and 00Z ECMWF maintain a broader swath of 850-mb winds in
excess of 30 kt, with forecast soundings from the RAP indicative of
a supercell wind profile. There may still be adequate low-level
convergence within the warm conveyor ahead of the front to support a
discrete supercell or two, which multiple CAMs simulate, most likely
across the Lower Keys. All modes of severe are possible, before
convection subsides overnight as convergence/ascent further weaken.

$$

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