-- Discussion containing changed information from previous version are highlighted. --
790
FXUS62 KKEY 181847
AFDKEY

Area Forecast Discussion
National Weather Service Key West FL
247 PM EDT Tue Jun 18 2024

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

.DISCUSSION...
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Issued at 247 PM EDT Tue Jun 18 2024

Surface analysis shows two features driving our winds; an
expansive high in the western North Atlantic and a large Central
American Gyre (CAG) over the Yucatan Peninsula. Marine
observation platforms are measuring winds of 15 to 22 knots along
the Reef, with the higher sustained winds in the western waters.
Showers in our southwestern waters that were previously riding
along in the fast easterly flow have waned for the most part, and
GOES Visible Satellite is depicting mostly clear skies across the
Florida Keys forecast area. This abundant sunshine has allowed
temperature to climb into the upper 80s.

The high in the western North Atlantic will slowly seep southward
over the next few days, Meanwhile, the CAG will meander around the
Yucatan while simultaneously spitting out possibly a few
disturbances. The locations of these features will keep a
tightened gradient across the region, and a prolonged period of
elevated easterly winds is expected. The Florida Keys will find
themselves in an area of weak confluence between the
aforementioned low and high pressures. The confluence plus the
moist easterly breezes will allow for above normal rain chances
(30-40%) for the next few days.

Thereafter, there is a decent amount of uncertainty regarding the
forecast and there is a lot of run-to-run inconsistencies with
the global models. The first question mark is the inverted trough
moving along in the easterlies that models have been attempting to
develop into a closed surface low the past few days before shoving
it somewhere along the Southeast coast. The strength of this
trough and if it can actually develop into a closed low will be
the deciding factors of if our winds will decrease for a brief
time later this week. The stronger the potential system is, the
more interruption in the ridge which could lead to a brief
decrease in winds later this week. Models have backed off on the
development of this trough, so winds will most likely remain
elevated through at least the start of the weekend. The second
question mark is the extent and timing of moisture streaming into
our area. The exact details are blurry on that, so have decided to
broad-brush 40% through most of the extended forecast. As we head
into next week, winds will have come down, which will act to
bring rain chances down a touch for the time being.
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&&

.MARINE...
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Issued at 247 PM EDT Tue Jun 18 2024

A Small Craft Advisory is in effect for all Florida Keys coastal
waters. From synopsis, strong surface high pressure centered off
the New England coast working in tandem with falling pressures
over the Yucatan Peninsula and the Bay of Campeche is expected to
result in moderate to fresh breezes tonight through late week. An
area of low pressure may develop mid week a few hundred miles
north of the central Bahamas towards mid week and move towards the
Southeast coast. This may result in a slackening of breezes, but
confidence is decreasing in the development of this system.
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&&

.AVIATION...
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(18Z TAFS)
Issued at 247 PM EDT Tue Jun 18 2024

VFR conditions will prevail at both EYW and MTH for the rest of
today and into tonight. While shower activity has dwindled from this
afternoon, there still remains a chance of showers through the
overnight hours. VCSH has been discontinued at both terminals due to
lack of activity but may be required again once showers develop
later this evening. Timing and exact coverage of developing
convection is too uncertain to include VCSH at this time. Near
surface winds will be out of the east to southeast at near 15 knots
with gusts up to near 25 knots.
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&&

.CLIMATE...
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In 1972, during the early morning hours, Tropical Storm Agnes passed northward
through the Yucatan channel. The outer rainbands of Tropical Storm Agnes
spawned at least three, to as many as six tornadoes in the Florida Keys,
including a F2 tornado in Big Coppitt Key, a F2 tornado in Key West, and a F1
tornado in Conch Key. Total damage was estimated at just over $500,000
(1972 USD). About 40 people were injured in Big Coppitt Key, making the Big
Coppitt Key tornado the worst in the history of the Florida Keys in terms of
total number of injuries.
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&&

.PRELIMINARY POINT TEMPS/POPS...
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Key West  82  89  82  89 /  30  40  40  50
Marathon  82  89  82  89 /  30  40  40  40
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&&

.KEY WATCHES/WARNINGS/ADVISORIES...
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FL...None.
GM...Small Craft Advisory for GMZ031>035-
042>044-052>055-072>075.
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&&

$$

Public/Marine/Fire...NB
Aviation/Nowcasts....JAM
Data Acquisition.....DR

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