Marathon Shores, Florida Weather Forecast Discussion

334
FXUS62 KKEY 070229
AFDKEY
Area Forecast Discussion
National Weather Service Key West FL
1029 PM EDT Sat Sep 6 2025
...New DISCUSSION, MARINE, AVIATION...
.DISCUSSION...
Issued at 1029 PM EDT Sat Sep 6 2025
KBYX radar was active from the mid to late afternoon through
sunset. A boundary was propagating southeastward across offshore
Gulf waters which merged with a cloud line that was bubbling along
the Island Chain. This resulted in showers and thunderstorms
developing in the vicinity of the Lower Keys. While thunder and
lightning may have been heard and seen on land, most of the
activity remained over the waters to the north with areas from
Cudjoe Key eastward to Bahia Honda being the main communities that
picked up rainfall. As soon as the sun set, the convection waned
since we lost the solar insolation and most of this activity had
been diurnally driven. MRMS data showed estimated rainfall amounts
of anywhere from a tenth of an inch to upwards of one inch with
the one inch in the vicinity of Big Torch Key. The heaviest
rainfall remained over the water where upwards of 2 inches was
estimated. GOES East Nighttime Microphysics imagery shows cloud
debris from earlier convection lingering north of the Island
Chain. Temperatures along the Island Chain are in the lower 80s
with dew points in the mid 70s. The cool spot due to rain cooled
air is Big Pine Key which was observing 77 degrees. A stagnant
pattern remains across the Keys with weak low pressure over the
west-central Gulf and weak high pressure over the Bahamas. As a
result, marine platforms are observing south to southwest breezes
of 5 to 10 knots.
.SHORT TERM FORECAST...
The 00z evening sounding shows a similar theme to the last couple
nights. The profile remains quite saturated with a PWAT value
measured of 2.30 inches is above the 90th percentile for the date.
The wind profile is slightly more favorable for showers tonight
showing a slight veering profile from basically due south near the
surface to southwesterly around 3000 ft AGL. The only caveat is
the winds are light. Based on this, no forecast changes are
expected as mesoscale processes and residual boundaries can spark
new showers or thunderstorms at any point in time. Right now, it
looks to favor the early morning again, similar to prior days
with the shower and thunderstorm threat continuing through the
daytime hours.
&&
.MARINE...
Issued at 1029 PM EDT Sat Sep 6 2025
There are currently no watches, warnings, or advisories in effect
across the Florida Keys coastal waters. From synopsis, a surface
trough will remain centered in the eastern Gulf and extend across
the Florida Peninsula through the remainder of the weekend and
well into next week. This trough along with continued very high
moisture levels and weak steering currents will generally result
in greater convective coverage through the forecast.
&&
.AVIATION...
(00Z TAFS)
Issued at 1029 PM EDT Sat Sep 6 2025
VFR conditions are expected to prevail at both terminals through
the TAF period. Latest guidance suggests the terminals remaining
dry through the overnight period. As we head towards daybreak,
there are some hints that convection will once again begin to
initiate throughout parts of the Keys. However, it remains too
uncertain at this time to say exactly where and when the terminals
will affected. Due to the relatively high rain chances, there is
a VCSH line in the TAF for somewhere around 07/12z with the risk
continuing into the afternoon since that seems to be when most
guidance shows activity near the terminals. The timing on this may
change in subsequent updates. Near surface winds are expected to
remain south to southwest (occasionally variable) between 4 to 8
knots.
&&
.PRELIMINARY POINT TEMPS/POPS...
Key West  89  79  91  80 /  70  70  50  50
Marathon  88  80  88  80 /  70  60  50  50
&&
.KEY WATCHES/WARNINGS/ADVISORIES...
FL...None.
GM...None.
&&
$$
Public/Marine/Fire...MJV
Aviation/Nowcasts....MJV
Data Acquisition.....DR
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NWS KEY Office Area Forecast Discussion