118
FXUS62 KKEY 220827
AFDKEY

Area Forecast Discussion
National Weather Service Key West FL
427 AM EDT Sat Jun 22 2024

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

.DISCUSSION...
Issued at 425 AM EDT Sat Jun 22 2024
The Keys are currently in a lull of convective activity after a
late evening Cuban outflow boundary brought a broken line of
shallow showers across the island chain. KBYX radar is generally
echo free near the island chain but a few showers are developing
off the northern coast of Cuba and sliding over our southernmost
border in the distant Straits of Florida. Offshore marine
observation platforms are reporting gentle to moderate east to
southeasterly breezes. These are a touch lower in magnitude than
the previous night resulting in less relief from this morning`s
steamy conditions. Temperatures across the island chain are in the
lower 80s with dewpoints close behind in the upper 70s to even
near 80.

Today and tonight`s forecast continues to be frustratingly
uncertain when it comes to PoPs. On one hand, many ingredients
are present for convective development. The weak low that pushed
ashore onto the north Florida Atlantic coastline pulled a great
deal of moisture into our area. Yesterday evening`s KKEY sounding
recorded a PWAT of 2.17 inches with a long, uncapped, and moist
lower to mid level profile. Slightly cyclonic surface flow from
the nearby low along with divergent flow aloft from the northeast
edge of the Central American Gyre (or CAG) and ridging over the
southeast CONUS should aid in the synoptic set up for rain today.

Despite this, some recent CAM runs are not particularly eager to
produce precipitation over the island chain and instead are
keeping most of the action in the Straits of Florida before
sending a brief flurry of showers our way later this afternoon.
Reasons for less convective coverage than initially thought
include a lack of lift to trigger initiation and a somewhat
discontinuous wind profile in the middle of the atmosphere
hindering extensive vertical growth. All that being said, opted to
stick with the high end chance PoPs (50%) which are notably lower
than MOS guidance but perhaps higher than what CAM runs are
suggesting. This choice is further supported by the already
developing convection in the Florida Straits that looks to be
quickly creeping northwest towards the island chain.

As the moist weekend comes to a close, the CAG will finally start
to retreat west and weaken allowing the usual Atlantic high to
build back over the Keys. Breezes will slacken even more at this
time as a typical wet season pattern takes over our sensible
weather. Prevailing east to southeasterlies will keep PoPs around
normal and return temperatures to just above normal values. There
might even be evidence for a cloud line day or two in the middle
of the week as breezes become lighter and practically variable in
the extended forecast.

&&

.MARINE...
Issued at 425 AM EDT Sat Jun 22 2024
There are no watches, warnings, or advisories currently in effect
for the Florida Keys coastal waters. From synopsis, the
interaction between 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 periods of unsettled weather through 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.

&&

.AVIATION...
(06Z TAFS)
Issued at 425 AM EDT Sat Jun 22 2024
VFR conditions will prevail at the EYW and MTH terminals through
Saturday evening. Above normal rain chances are expected, however
exact timing or coverage of convection will be difficult to
forecast, so have included just VCSH throughout the TAF period for
now. Short-term amendments will be issued as needed, based mainly on
radar trends. Short periods of MVFR or even IFR conditions will be
possible if convection directly impacts a terminal. Outside of any
stronger convection, surface winds will remain from the east to
southeast at 6 to 11 knots.

&&

.CLIMATE...
On this day in Keys weather history, in 1990 the daily record
rainfall of 4.30" was recorded at Marathon International Airport.
This is also the wettest day ever recorded in the Marathon area
for the month of June. Rainfall records for Marathon date back to
1950.

&&

.PRELIMINARY POINT TEMPS/POPS...
Key West  88  81  88  80 /  50  50  50  40
Marathon  88  81  88  81 /  50  50  50  40

&&

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

$$

Public/Marine/Fire...JAM
Aviation/Nowcasts....Jacobson
Data Acquisition.....Jacobson

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