883
FXUS62 KKEY 200842
AFDKEY

Area Forecast Discussion
National Weather Service Key West FL
442 AM EDT Wed Aug 20 2025

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

.DISCUSSION...
Issued at 337 AM EDT Wed Aug 20 2025
Weather conditions along the island chain are much calmer compared
to last night! Our KBYX radar has been virtually void of any
shower activity within the Florida Keys coastal waters over the
past few hours, and we anticipate this to remain the case going
into the early morning. However, a pool of moisture in the lower
levels could still be enough to support some typical August
afternoon convection. We could split the PoP forecast for today to
reflect lower chances in the morning and early afternoon, and the
advertised 30 percent being the case for the late afternoon and
evening, but we`re opting to go with a straight 30 percent PoP for
today since there is some shower activity occurring outside of
our nearby waters. Nighttime Microphysics shows only a few clouds
in the area, reflecting the comparatively drier air aloft.
Overall, a very benign starting point for the day ahead. The
northwesterly flow we are currently seeing on surface observations
isn`t typical for this time of year, but this is a flow
associated with particularly hot temperatures. Even though there
are no heat hazard products, heat indices may briefly touch 105F
to 108F today. Please keep this in mind when going about the day.

Hurricane Erin is still well to our northeast this morning,
approximately 600 miles northeast of Key West as of 4 AM EDT, and
the system is continuing to follow its northward track. As the
system moves farther away, higher pressure will build in its
place. Mean layer flow will shift to the west and southwest by
Wednesday night or Thursday, but there is some lower confidence
with regard to whether or not we can get a reverse cloudline to
set up during the daytime. The GFS is resolving some unusually
dry air considering the time of year, how hot it has been, and how
much water the air mass will sit over. On the other hand, EC
suggests enough moisture may linger in the lower levels through
the rest of the week, and that moisture could support cloudline
development. Due to the small scale nature of our local
cloudlines, this is something that global guidance will not
resolve clearly.

Otherwise, as we approach the end of the week and head into the
weekend, the high pressure transversing the area will encourage a
lack of cloud cover and nearly stagnant air. Any breezes we do
sustain will be light to gentle, so don`t expect too much relief
from the August heat. Rainfall chances will remain near normal for
the time of year, but without a synoptic lifting mechanism in
place, we will depend on mesoscale features (such as outflows from
mainland convection) to trigger out own activity.

&&

.MARINE...
Issued at 337 AM EDT Wed Aug 20 2025
There are no watches, warnings, or advisories in effect for the
Florida Keys local waters. From synopsis, Hurricane Erin will
continue to follow a mainly northerly track today. The
increasingly expansive circulation of Erin will result in a
transition from light to gentle variable breezes early this
morning to gentle to moderate northwest breezes by Tuesday
followed by moderate to fresh westerly breezes on Wednesday. A
slight swell from the north will lead to elevated seas in eastern
portions of the Florida Straits. As Hurricane Erin migrates
farther away toward the north and northeast, a weak subtropical
high pressure ridge will settle over Florida Keys coastal waters,
resulting in a lighter wind pattern Thursday through Saturday.

&&

.AVIATION...
(06Z TAFS)
Issued at 337 AM EDT Wed Aug 20 2025
VFR conditions will prevail at both island terminals through the TAF
period. Some model guidance suggests the terminals remaining dry
throughout the TAF period while other guidance suggests showers and
thunderstorms developing during the afternoon and continuing into
the evening hours. Due to the uncertainty in timing, placement, and
if and when a shower or thunderstorm will develop that might impact
the terminals, VCSH/VCTS was left out of the TAF for now. However,
VCSH/VCTS may be added in subsequent updates. Near surface winds
will remain west to northwest between calm to 5 knots this morning
before increasing to 8 to 15 knots this afternoon into the early
evening before diminishing later in the evening with higher gusts in
any convection.

&&

.CLIMATE...
On this day in Keys weather history, in 2024, the daily record warm
low temperature of 85F was last recorded in Key West. Temperature
records for Key West date back to 1872.

Also, in 2022, the daily record warm low temperature of 85F was last
recorded in Marathon. Temperature records for Marathon date back to
1950.

OF NOTE
In 2019, WFO Key West recorded 5.72" of rainfall for the
day. 5.66" of that total fell in less than 12 hours. A mesonet site
near the intersection of Simonton and Angela Streets recorded 7.22"
for the day. Including these two, four observation sites from
midtown to Old Town recorded over 5" of rainfall on this day.

&&

.PRELIMINARY POINT TEMPS/POPS...
Key West  93  82  92  82 /  30  30  30  30
Marathon  91  82  91  83 /  30  30  30  30

&&

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

$$

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

Visit us on the web at weather.gov/key

Follow us on Facebook and Twitter at:
www.facebook.com/nwskeywest
www.twitter.com/nwskeywest