825
FXUS62 KKEY 271752
AFDKEY

Area Forecast Discussion
National Weather Service Key West FL
152 PM EDT Sun Sep 27 2026

...New AVIATION...

.KEY MESSAGES...

- Saltwater flooding of low elevation streets and lots is likely
  through this week due to a potent King Tide. Don`t drive
  through flooded roadways. Boaters can expect less clearance
  under fixed bridges.

- A Coastal Flood Advisory is in effect for the Lower to Middle
  Keys, and a Coastal Flood Warning is in effect for the Upper
  Keys..

- Northeasterly swell from a Nor`easter off the East Coast will
  continue to produce 2 to 4 foot seas through tonight in the
  eastern Straits of Florida.

&&

.AVIATION...
(18Z TAFS)
Issued at 144 PM EDT Sun Sep 27 2026

VFR conditions will prevail at EYW and MTH for the upcoming TAF
period. Near surface winds will slowly decrease and shift westerly
during the evening and midnight hours. Cloud cover will be
patchy, but CIGs at MVFR heights are very unlikely. Shower
coverage will remain sparse.

&&

.MARINE...
Issued at 1010 AM EDT Sun Sep 27 2026
There are no watches, warnings, or advisories in effect across
the Florida Keys coastal waters. From synopsis: a nor`easter
remains off the coast of New Jersey which will continue to support
a northeasterly swell with large periods in the eastern marine
zones through tonight, before subsiding tomorrow. A weak frontal
boundary will begin to push back northward through the marine
zones on Monday. Winds will then clock back to the southeast to
south for early this week, also accompanied by increasing rain and
thunder chances. In addition, strengthening high pressure is
expected to move off the Southeast U.S. coastline around the
middle to latter half of next week, merging with the Atlantic
high. This will promote freshening east to southeast breezes,
potentially become moderate to fresh.

&&

.PREV DISCUSSION...
Issued at 413 AM EDT Sun Sep 27 2026
Pleasant conditions are in place across the Florida Keys this
morning. Surface obs are reporting dewpoints in the upper 60s to
near 70 along the lower to middle island chain and this should
persist through the day today with light to gentle northerly
breezes and mostly sunny skies. Water vapor satellite imagery
clearly shows a strong nor`easter spinning along the New England
coast, the axis of which extends south-southwest and almost
directly across the Keys. This system is flanked on both sides by
broad ridging, resulting in somewhat of a blocking pattern. Things
will get moving again over the next couple of days as a deepening
longwave trough begins to push in from the Pacific and across the
Four Corners while the nor`easter breaks down and ejects towards
the northern Atlantic.

Currently, tidal gauges along the eastern Florida Peninsula and now
into the Keys have shown a steady rise in tidal anomalies well above
projected levels. This is partly due to the Full Moon but also due
to a backup of the Gulf Stream as a result of the gale force
northerly winds along the East Coast associated with the nor`easter.
The tide station at Ocean Reef recently reported a peak in major
flood. This backup is expected to gradually work its way down the
Keys over the next few days with high tide projections showing an
increase, especially at high tide tonight and Monday night. As such,
the Coastal Flood Advisory was upgraded to a Warning for the Upper
Keys while a Coastal Flood Statement remains in effect for the Lower
to Middle Keys due to saltwater flooding. An upgrade to an Advisory
will likely be needed for the Lower to Middle Keys by tonight or
tomorrow at the latest. Residents in the Upper Keys should take the
necessary actions to protect flood-prone property. Persistent
puddles around the times of high tide are almost certain to contain
a mix of saltwater. Also, northerly swell in the eastern Straits
of Florida will gradually subside today and tomorrow.

Longwave troughing is expected to deepen across the Southeast and
into the Gulf tonight in association with the nor`easter. In the
lower-levels, the Atlantic ridge will begin to build across the
Keys which will promote a swing towards west-southwesterly low-
level flow during the day tomorrow. We`ll see a rapid resurgence
in tropospheric moisture right as the mid to upper-level trough
axis is deepening over the Gulf. A wet and stormy period looks to
develop as early as tomorrow night with waves of activity possible
through at least the middle of the week. Global models are
suggesting that as the nor-easter departs into the Atlantic,
leftover mid to upper-level troughing will be cutoff and left
behind over the Gulf or Yucatan while the Atlantic ridge begins
to establish it`s dominance across the region in the lower-levels.
This will be a complex setup that may culminate into a sustained
wet and breezy period through the latter half of the week,
becoming increasingly problematic if rounds of heavy rainfall
were to compound with ongoing King Tides.

&&

.PRELIMINARY POINT TEMPS/POPS...
Key West  77  88  77  88 /  10  30  60  70
Marathon  78  86  78  87 /  10  20  60  70

&&

.KEY WATCHES/WARNINGS/ADVISORIES...
FL...Coastal Flood Warning until 6 AM EDT Monday for FLZ076.

     Coastal Flood Advisory until 6 AM EDT Monday for FLZ077-078.

GM...None.
&&

$$

Public/Marine/Fire...AJP
Aviation/Nowcasts....AJP
Data Acquisition.....AJP

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