Long Key, Florida Weather Forecast Discussion

956
FXUS62 KKEY 080829
AFDKEY
Area Forecast Discussion
National Weather Service Key West FL
429 AM EDT Mon Sep 8 2025
...New DISCUSSION, MARINE, AVIATION...
.DISCUSSION...
Issued at 415 AM EDT Mon Sep 8 2025
Mid latitude troughing over eastern North America and southern
stream troughing sweeping through the Gulf are contributing to
persistent lower level troughing over the eastern Gulf and across
Florida. In addition, this continues to maintain a broad swath of
very high precipitable water across Florida and the Keys.
Overall, a wetter than normal pattern remains across our area.
The troughing has also had a hand in crafting periods of broad low
level confluence across Florida and the Keys. After a mostly quiet
evening, shower and thunderstorms activity has increased quite a
bit across our area.
The lack of ridging at any level, along with the semi permanent
lower level trough across Florida and the Gulf, will maintain
higher chances for showers and thunderstorms for the next couple
of days. Adding to this, deep layered moisture will remain quite
high with forecast soundings generally depicting a nearly
saturated column through the troposphere. The overall weakness of
the lower level flow means mesoscale factors will often determine
timing and location of convective initiation. Will maintain high
chance to likely pops through this period. Expect seasonal
temperatures with dew points in the mid to upper 70s.
Rain chances may dip a bit heading into mid week. This is a result
of the trough to our north lifting a bit further north and as its
eastern flank is yanked away by a lifting out short wave trough
further north. Precipitable water is also expected to slip some
with modestly drier air showing up through the lower levels. With
that said, the environment will remain quite capable of showers
and thunderstorm development. A continued weak flow will keep the
door open for sea breeze and island cloud line triggers.
Guidance is becoming increasingly insistent that a stalled
frontal boundary, associated with the old surface trough, will
push southwards towards our area through the back half of the
week. This will be driven by complicated amplification of an
upper level trough over the eastern United States and Gulf. Not
only is deep layered moisture expected to still remain high, the
potential for upper level support will likely be on the rise as
short waves round the bottom of the trough within a diffluent
flow. The surface flow will remain chaotic and changeable due the
surface pressure field remaining poorly defined and perturbed
daily by diurnal and convective influences. As a result of the
above, have nudged PoPs up a bit for the mid to long range. With
that said, uncertainty is rather high.
&&
.MARINE...
Issued at 415 AM EDT Mon Sep 8 2025
Troughing will linger over the eastern Gulf and Florida for the
next couple of days. This will result in light to gentle mostly
south to southwesterly breezes on Keys waters. The overall wet
pattern that has driven episodes of shower and thunderstorm
activity will continue. Heading into mid week, the trough to our
north will lift northward and weaken as the Atlantic ridge
attempts to swing northward out of Cuba. However, the pressure
field will remain lackluster. While light broadly southerly
breezes will prevail, expect quite a bit of variability.
&&
.AVIATION...
(06Z TAFS)
Issued at 415 AM EDT Mon Sep 8 2025
VFR conditions are expected to largely prevail this morning at EYW
and MTH. That said, a passing shower or two is possible based on
radar trends, so opted to add in VCSH for now. Mention of more
specific impacts and categorical changes will be handled by future
updates and amendments. Winds will generally be from the south at 5
to 10 knots.
&&
.CLIMATE...
On this day in 1965, category 3 Hurricane Betsy moved west across
the Upper Keys, through Florida Bay and north of the Lower Keys. Key
West measured a peak wind of 81 mph and a storm tide of 5-7 ft,
while Big Pine experienced winds of 125-140 mph with gusts to 165
mph. Rain bands of Hurricane Betsy produced a daily-record 3.90" of
rain at Key West.
&&
.KEY WATCHES/WARNINGS/ADVISORIES...
FL...None.
GM...None.
&&
$$
Public/Marine/Fire...11
Aviation/Nowcasts....MC
Data Acquisition.....MC
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NWS KEY Office Area Forecast Discussion