846
FXUS62 KKEY 271411
AFDKEY
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE KEY WEST FL
1011 AM EDT SUN SEP 27 2026
..NEW DISCUSSION, MARINE, 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 STATEMENT IS IN EFFECT FOR THE LOWER TO MIDDLE
KEYS, AND A COASTAL FLOOD WARNING IS IN EFFECT FOR THE UPPER
KEYS. COASTAL FLOOD ADVISORIES WILL LIKELY BE REQUIRED FOR THE
LOWER TO MIDDLE KEYS BY TONIGHT.
- NORTHEASTERLY SWELL FROM A NOR'EASTER OFF THE EAST COAST WILL
CONTINUE TO PRODUCE 3 TO 4 FOOT SEAS THROUGH TODAY IN THE
EASTERN STRAITS OF FLORIDA.
DISCUSSION
ISSUED AT 1010 AM EDT SUN SEP 27 2026
AN EARLY COLD FRONT WAS ABLE TO BRING A DRIER AIR MASS SOUTH TO
THE FLORIDA KEYS LAST WEEK. WHILE IT TOOK TIME, THE DRIER AIR
FINALLY MADE IT TO THE SURFACE. MORNING DEW POINTS ACROSS THE KEYS
WERE IN THE UPPER 60S, A WELCOME CHANGE FROM THE MONTH OF MID TO
UPPER 70S. SATELLITE OBSERVATIONS FROM GOES EAST ESTIMATED TOTAL
PWATS BETWEEN 1.2 AND 1.4 INCHES ACROSS THE ISLAND CHAIN, WHICH
WAS CORROBORATED BY THE 12Z KKEY SOUNDING. WHILE THE BALLOON
MEASURED A DEW POINT ABOVE THE 10TH PERCENTILE FOR THE DAY, THE
ENVIRONMENT IS STILL VERY DRY FOR LATE SEPTEMBER. ONLY SPARSE
SHOWERS WERE OBSERVED BY THE KBYX RADAR THIS MORNING. MEANWHILE,
BREEZES ALONG THE REEF ARE SLACKENING TO LIGHT TO VARIABLE
NORTHWESTERLIES. OVERALL, THERE IS NOT MUCH TO WRITE ABOUT IN
TERMS OF WEATHER ACROSS THE KEYS FOR THIS AFTERNOON. MARINE
CONDITIONS, ON THE OTHER HAND, ARE MORE COMPLICATED.
A POTENT NOR'EASTER JUST OFFSHORE OF NEW ENGLAND HAS BEEN
GENERATING NORTHERLY SWELL THAT HAS INCREASED WAVE HEIGHTS OVER
THE EASTERN WATERS OF THE FLORIDA STRAITS. UNFORTUNATELY, THIS
SWELL OCCURRED DURING A PEAK IN THE TIDE CYCLE. KING TIDES ARE A
CONCERN EACH SEPTEMBER, BUT THE NORTHERLY SWELL IS ADDING TO THE
ALREADY HIGH TIDES. A COASTAL FLOOD WARNING WAS REQUIRED FOR THE
UPPER KEYS LAST NIGHT AND WE ARE NOT NEAR THE PEAK OF THE TIDAL
CYCLE. IT IS LIKELY A COASTAL FLOOD ADVISORY WILL BE REQUIRED FOR
THE LOWER AND MIDDLE KEYS BEFORE TOMORROW MORNING.
LATE TONIGHT, EXPECT WINDS TO REMAIN LIGHT TO VARIABLE. THE
ENVIRONMENT IS PRIMED TO STAY DRY, BUT THE WEATHER PATTERN IS
BEGINNING TO SHIFT. MID TO UPPER LEVEL WINDS WILL BEGIN TO SHIFT
WESTERLY TO SOUTHEASTERLY BY THE END OF THE NIGHT AND DIRECT
ADDITIONAL MOISTURE ACROSS THE KEYS. ENJOY THE DRIER WEATHER WHILE
YOU CAN, BECAUSE IT IS STILL WET SEASON.
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.
AVIATION
(12Z TAFS)
ISSUED AT 1010 AM EDT SUN SEP 27 2026
VFR CONDITIONS PREVAIL AT EYW AND MTH FOR THE UPCOMING TAF
PERIOD. WHILE CLOUD COVER WILL WAX AND WANE ACROSS THE ISLAND
CHAIN, CIGS ARE NOT EXPECTED BELOW FL030. NEAR SURFACE WINDS ARE
ON TRACK TO SLACKEN WITH LIGHT AND VARIABLE PERIODS POSSIBLE.
SHRA, IF PRESENT, WILL BE SPARSE AND SHORT LIVED.
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 87 77 88 77 / 10 10 30 60
MARATHON 85 78 86 78 / 10 10 20 60
KEY WATCHES/WARNINGS/ADVISORIES
FL...COASTAL FLOOD WARNING UNTIL 5 PM EDT THIS AFTERNOON FOR FLZ076.
GM...NONE.
PUBLIC/MARINE/FIRE...AJP
AVIATION/NOWCASTS....AJP
DATA ACQUISITION.....AJP
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