914
FXUS62 KKEY 251624
AFDKEY

Area Forecast Discussion
National Weather Service Key West FL
1224 PM EDT Wed Sep 25 2024

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

.DISCUSSION...
Issued at 1218 PM EDT Wed Sep 25 2024
KBYX radar showed a cluster of showers and thunderstorms
associated with the far outer bands of Hurricane Helene earlier
this morning racing to the northwest near 35 knots or 40 mph. As
this cluster approached the Upper Keys it produced a wind gust up
to 38 knots or 43 mph at Alligator Reef Light. A more consolidated
outer rain band associated with Helene stretches from the Gulf of
Mexico east into the southwestern waters of the Florida Keys and
then southeastward over Cuba and into the northwest Caribbean Sea.
This band of rain hasn`t been able to make much progress to the
northeast as of yet and has remained mostly over the same areas
for a decent chunk of the morning. Outside of the rain bands,
marine platforms are observing 15 to 20 knots except for Sand Key
which has been gusting between 25 to 30 knots for the last couple
hours. They also have recorded a 34 knot gust in the past hour. We
observed 32 knots on the roof upstairs here at the office on
White Street in Key West also within the past hour. Temperatures
along the Island Chain are in the mid to upper 80s with dew points
in the upper 70s. The cloud cover from Helene is helping to keep
temperatures in check for today.

Over the next few to several hours, we will continue to see
southeasterly winds increase as Helene continues to move to the
northwest, then to the north later today and then north to
northeast this evening into the overnight hours while continuing
to strengthen into a major hurricane as it heads towards the Big
Bend of Florida where a landfall is anticipated sometime Thursday
evening/night. Helene is expected to make its closest pass to the
Keys overnight tonight with winds peaking overnight out of the
southeast to south continuing through Thursday morning. As the
storm continues to move away, winds will become more southerly and
then south to southwesterly late in the day on Thursday while
slowly diminishing. Regarding rainfall, we will likely see the
band currently southwest of us move over, especially the Lower
Keys this evening continuing through the overnight as it pivots.
Outside of this, we can`t rule out clusters of showers and
thunderstorms to move through the Keys. Also, see coastal flood
section below as any surge is expected to begin this evening
continuing into Thursday/Thursday evening.

&&

.MARINE...
Issued at 1218 PM EDT Wed Sep 25 2024
A Tropical Storm Warning remains in effect across the Florida
Keys coastal waters. From synopsis, southeasterly breezes will
continue to freshen quickly this afternoon as Tropical Storm
Helene crosses the Yucatan channel and emerges over the southern
Gulf. Thereafter, the storm will track northeastward toward the
Big Bend region of Florida, and we will see the closest pass from
Helene to the Florida Keys coastal waters later this evening
through Thursday morning when the peak southeasterly wind and
highest seas is expected to occur. As the storm passes, breezes
will shift to the south to southwest while gradually diminishing
with seas gradually subsiding Thursday night through Friday. Winds
further diminish heading through the weekend.

.COASTAL FLOOD...
A Coastal Flood Warning remains in effect across the Florida Keys
coastal waters from midnight tonight through Thursday night. Minor
saltwater flooding will continue across the Florida Keys through
this afternoon, especially around the times of high tide. Major
saltwater flooding of 1 to 3 feet above ground level at the lowest
elevation areas and shoreline is expected from this evening
through Thursday evening, with strong southeast to south winds
impacting the Florida Keys as Tropical Storm Helene moves
northward through the eastern Gulf of Mexico and intensifies into
a major hurricane. The initial storm surge flooding threat will
be primarily on the oceanside beginning this evening, with a
possible Gulf side surge occurring on Thursday into Thursday
evening as winds shift to south or southwest.

&&

.AVIATION...
(15Z TAFS)
Issued at 1218 PM EDT Wed Sep 25 2024
Both terminals are experiencing the "calm before the storm" in terms
of convective activity. Winds have gradually been increasing through
the morning, with measured gusts of 20 to 25 knots at MTH and
measured gusts of 25 to 30 knots at EYW. Both convective coverage
and winds will steadily increase through the TAF period, with peak
winds expected late tonight through tomorrow morning. Gusts at both
sites could reach 40 knots or greater outside of squalls, and 55 to
60 knots within squalls. Any passing squalls will require short term
amendments, as the confidence in the exact timing of them is low.
Conditions will start to slowly improve by tomorrow afternoon, so
will start to gradually trend winds downward in the next TAF
cycle.

&&

.PRELIMINARY POINT TEMPS/POPS...
Key West  85  82  85  82 /  90  90  80  60
Marathon  87  81  88  81 /  80  80  80  60

&&

.KEY WATCHES/WARNINGS/ADVISORIES...
FL...Coastal Flood Warning until midnight EDT Thursday night for
     FLZ076>078.

     Tropical Storm Warning for FLZ076>078.

GM...Tropical Storm Warning for GMZ031>035-042>044-052>055-072>075.

&&

$$

Coordinator/Hazards..BT
Public/Marine/Fire...MJV
Aviation/Nowcasts....NB
Social Media.........AP
Data Acquisition.....AP

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