429
FXUS62 KKEY 150834
AFDKEY

Area Forecast Discussion
National Weather Service Key West FL
434 AM EDT Tue Jul 15 2025

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

.DISCUSSION...
Issued at 434 AM EDT Tue Jul 15 2025
The overnight hours have been generally quiet up until recently.
KBYX radar is detecting a cluster of showers and thunderstorms
extending from the Southwest mainland of Florida westward across
the northern offshore Gulf waters of the Keys. This cluster of
showers and thunderstorms is moving southeast to south between 10
to 15 knots. MRMS data shows estimated rainfall amounts of a half
to one inch with these storms with in excess of 1 inch in the
heaviest activity. GOES East Nighttime Microphysics imagery shows
an area of low pressure trying to become better organized just
off the Space Coast of Florida. This can be seen in the cloud
pattern which is depicting a cyclonic spin. Across the Keys, there
is mainly high cirrus across the Island Chain into the Straits of
Florida with the cumulonimbus clouds associated with the
aforementioned activity over the northern Gulf waters.
Temperatures along the Island Chain are in the upper 70s to lower
80s and dew points are in the lower to mid 70s. The Big Pine Key
RAWS is currently observing 73 degrees which is the cool spot once
again tonight.

Weak low pressure continues to try to develop off the Space Coast
of Florida. It is also looking the healthiest it ever has so far
early this morning. This low will continue moving to the west with
high pressure building in behind it as the high shifts westward
across the western North Atlantic. Since the Keys are to the south
of the low and on the western periphery of the high trying to
build in, marine platforms around the Keys are observing mainly
south breezes of 5 to 10 knots. Island Chain communities are
observing south to southwest breezes near 5 mph.

.FORECAST...
The focus for today through Wednesday continues to be on the
aforementioned low pressure to the east of the Space Coast this
morning. The National Hurricane Center currently gives this system
a 40% chance of development over the next 48 hours and 7 days.
While the core of this low pressure system is expected to remain
well north of the Keys, there will be plenty of cyclonic
vorticity/vort maxes rotating around the system resulting in
another round of showers and thunderstorms throughout the Keys
today. Therefore, 80% chance of rain remains in the forecast for
today. The vort maxes will continue to slowly move off to the west
as the system moves towards the North Gulf Coast. However, this
will continue to keep grips on the Keys through Wednesday
resulting in 60% chance for rain tonight across the Keys with 70%
for Wednesday due to a bit more rigorous upper level energy
coupled with daytime heating. Any storms will be capable of
producing strong gusty winds, locally heavy rainfall, and frequent
lightning. The Weather Prediction Center (WPC) has the Keys
highlighted in a marginal risk (Level 1 out of 4) for today.

A more typical summer time pattern returns for the second half of
the week and into the weekend. High pressure over the Atlantic
builds into Florida bringing a return to the east to
southeasterlies along with moisture undulations moving around the
western periphery of the high. As a result, expect rain chances
of 40% for Wednesday night and 50% for Thursday due to a slight
uptick in the moisture before rain chances return to around normal
for late week and into the weekend. Rain chances might even dip
slightly below normal to around 20% some periods. Also, it will
for sure be summer with highs near 90 degrees and overnight lows
in the lower 80s. Heat index values are expected to range from
102-107 degrees through this period which is just under Heat
Advisory criteria.

Towards the end of the extended, model guidance is beginning to
show signs of a TUTT- Tropical Upper Tropospheric Trough moving
westward into the Keys to start early next week. This TUTT cell
will originate over the western North Atlantic near the Bahamas
before migrating westward. This may result in an uptick in rain
chances to start the new work week, though, this remains uncertain
right now. The timing, strength, and exact movement of this cell
will be ironed out over subsequent forecast cycles.

&&

.MARINE...
Issued at 434 AM EDT Tue Jul 15 2025
There are currently no watches, warnings, or advisories in effect
across the Florida Keys coastal waters. From synopsis, weak low
pressure continues to become better organized in the vicinity of
the Space Coast. However, the overall pressure pattern remains
rather weak, therefore, light to gentle southeast to south breezes
are expected to continue today. In addition, another round of
showers and thunderstorms are expected today with the main threats
being gusty winds and confused seas near convection. As the weak
low pressure shifts off to the west and into the Gulf, high
pressure will build in behind it strengthening the pressure
gradient. This will lead to gentle to moderate breezes tonight.
High pressure remains anchored over the central Atlantic with its
western periphery extending into the Keys through the weekend with
gentle to moderate east to southeast breezes continuing,
occasionally becoming moderate to fresh.

&&

.AVIATION...
(06Z TAFS)
Issued at 434 AM EDT Tue Jul 15 2025
VFR conditions will largely prevail at EYW and MTH through the
TAF period, though expected showers and thunderstorms are likely
to produce periods of sub-VFR conditions, especially after 12z.
Confidence is high that this will occur, but sufficient
confidence in timing is not enough to pinpoint specific mention in
the TAFs for the moment. VCSH mention after sunrise will provide
the general timing for now, and later TAF amendments and routine
issuances will cover specifics as needed. Winds will be light and
variable through sunrise, then become light to gentle generally
from the southeast to south.

&&

.CLIMATE...
On this day in 1987, the daily record high temperature of 99F was
recorded at Marathon. This is also tied for the warmest
temperature ever recorded for the month of July, or any month, for
the Marathon area. Temperature records for Marathon date back to
1950.

&&

.PRELIMINARY POINT TEMPS/POPS...
Key West  86  79  88  82 /  80  60  70  40
Marathon  87  79  89  82 /  80  60  70  40

&&

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

$$

Public/Marine/Fire...MJV
Aviation/Nowcasts....MC
Data Acquisition.....MC

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