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444
FXUS62 KKEY 211855
AFDKEY

Area Forecast Discussion
National Weather Service Key West FL
255 PM EDT Fri Jun 21 2024

...New DISCUSSION, MARINE, AVIATION...

.DISCUSSION...
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Issued at 226 PM EDT Fri Jun 21 2024
Shower and thunderstorm activity has largely struggled thus far
today. This is despite broad cyclonic flow in the mid- and upper-
levels, no discernible convective cap, and deep, tropical
tropospheric profile sampled by the 12z sounding at KEY this
morning. We are admittedly a bit puzzled by the lack of convective
development, given this environment. GOES-16 visible satellite
imagery is highlighting partly to mostly cloudy skies across the
Florida Keys island chain and the adjacent nearshore and offshore
coastal waters, with only a few widely scattered showers and
isolated thunderstorms being detected by KBYX Doppler radar. Land-
based surface observations are reporting temperatures generally
in the upper 80s across the Keys.

For tonight through much of the weekend, the synoptic-scale
environment will remain largely unaltered. The only ingredient
seeming to be lacking thus far is a trigger to get this convection
going. At this time, given the largely supportive environment for
convection, it seems prudent to retain middle of the road
measurable rain chances for the weekend. With deep tropospheric
moisture, nearly every shower that does form will have the
potential to morph into a thunderstorm as well. The main question
remains when the aforementioned trigger fires. All convective
allowing model (CAM) guidance has struggled with this key
ingredient, with many different run-to-run and model-to-model
solutions.

As a monsoonal low in the vicinity of the Bay of Campeche finally
weakens late in the weekend, high pressure will slowly build
across the North Atlantic and through the Florida Peninsula. This
will finally setup a typical summertime pattern for the Florida
Keys, with convection limited to either moisture undulations in
the east to southeasterlies or diurnally-driven island cloud line
formation on days with lighter steering flow. Temperatures this
weekend will remain at or below average due to bouts of rainfall
and elevated cloud cover, and these temperatures will slowly
moderate to at near or just above normal levels for next week.
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&&

.MARINE...
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Issued at 226 PM EDT Fri Jun 21 2024
There are currently no watches, warnings, or advisories in effect
across the Florida Keys coastal waters. From synopsis, interaction
among low pressure off the east coast of Florida, high pressure
centered north of Bermuda, and broad low pressure in the vicinity
of the Yucatan Peninsula will result in gentle to moderate east to
southeast breezes over the next few days. Moisture pulled into
our area via the low to the west will result in waves of unsettled
weather this weekend. High pressure building over the North
Atlantic early next week will result in light to gentle southeast
to south breezes and a return to near- normal rain and thunder
chances.
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&&

.AVIATION...
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(18Z TAFS)
Issued at 226 PM EDT Fri Jun 21 2024
VFR conditions will prevail at both EYW and MTH through the TAF
period. Shower activity could return later this evening, but
confidence in any impacts is low, so only VCSH is included for the
time being. Near surface winds are easterly at near 10 knots.
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&&

.PRELIMINARY POINT TEMPS/POPS...
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Key West  81  89  80  89 /  50  50  50  50
Marathon  80  90  80  90 /  50  50  50  50
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&&

.KEY WATCHES/WARNINGS/ADVISORIES...
FL...None.
GM...None.
&&

$$

Public/Marine/Fire...BT/AJP
Aviation/Nowcasts....AP
Data Acquisition.....DR

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