845
FXUS62 KKEY 091915
AFDKEY
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE KEY WEST FL
315 PM EDT FRI OCT 9 2026
..NEW DISCUSSION, MARINE, AVIATION
KEY MESSAGES
- A COASTAL FLOOD STATEMENT IS IN EFFECT, AND PARTICULARLY LOW
LYING AREAS WILL SEE SOME SALTWATER PONDING AROUND THE TIMES OF
HIGH TIDE.
- MAJOR HURRICANE ISAIAS IN THE GULF DOES NOT POSE A DIRECT
THREAT TO THE FLORIDA KEYS, BUT IT WILL BRING INCREASING
WESTERLY SWELL INTO THE REGION FOR THE FIRST HALF OF THE
WEEKEND.
- WINDS WILL BE ELEVATED OVER THE WATERS SURROUNDING THE LOWER
KEYS EARLY THIS EVENING.
- INCREASING MOISTURE ACROSS THE KEYS TONIGHT THROUGH SATURDAY
NIGHT WILL LEAD TO HIGHER RAIN CHANCES. THE PEAK IN ACTIVITY IS
EXPECTED TONIGHT.
DISCUSSION
ISSUED AT 315 PM EDT FRI OCT 9 2026
MAJOR HURRICANE ISAIAS, NOW A CATEGORY 3 HURRICANE, IS FORECAST
TO MAKE LANDFALL ALONG THE FLORIDA PANHANDLE TONIGHT. WHILE DIRECT
IMPACTS TO THE FLORIDA KEYS ARE NOT EXPECTED, THE TROPICAL
CYCLONE IS MODIFYING THE ENVIRONMENT AROUND THE KEYS. BREEZES
ALONG THE REEF WERE ABLE TO BUILD TO FRESH SOUTHEASTERLIES BECAUSE
MAJOR HURRICANE ISAIAS INTENSIFIED AND MOVED FURTHER EAST THAN
PREVIOUSLY FORECAST. WAVE HEIGHTS IN THE OUTER GULF WATERS AND THE
WESTERN FLORIDA STRAITS ARE HIGHER THAN NORMAL DUE TO THE
HURRICANE. SIGNIFICANT WAVE HEIGHTS WEST OF THE DRY TORTUGAS MAY
BECOME AS HIGH AS 7 FEET THIS AFTERNOON. EVEN WHEN THE HURRICANE
MOVES INLAND, WAVES WITHIN THE GULF WILL CONTINUE TO BE AMPLIFIED
THROUGH THE FIRST HALF OF THE WEEKEND.
WHILE THE HURRICANE IS THE MOST PROMINENT WEATHER FEATURE NEARBY,
IT IS NOT THE ONLY PATTERN OF INTEREST FOR THE FLORIDA KEYS. A
TROPICAL UPPER TROPOSPHERIC TROUGH (TUTT) IS SPINNING SOUTH OF
CENTRAL CUBA. OVER THE PAST FEW DAYS, THE TUTT HAS SLOWLY MADE ITS
WAY WEST ACROSS THE CARIBBEAN. DURING THE MIDDLE OF THE WEEK, IT
CAME INTO PHASE WITH A WEAK WAVE IN THE LOWER ATMOSPHERE LOCATED
OVER HISPANIOLA AND EASTERN CUBA. CIMSS SATELLITE DERIVED
VORTICITY WAS ABLE TO TRACK THIS IMPULSE TO JUST SOUTH OF THE
BAHAMAS.
THIS AFTERNOON, SHOWERS WERE RELATIVELY SPARSE ACROSS THE FLORIDA
KEYS. MAJOR HURRICANE ISAIAS GENERATED A REGION OF SINKING AIR
AROUND IT, WHICH KEPT SHOWER ACTIVITY LOW OVER SOUTH FLORIDA.
CLOUD COVER IS GRADUALLY STARTING TO INCREASE ACROSS THE KEYS
WATERS, HOWEVER, AS THE PREVIOUSLY MENTIONED WAVE MOVES TOWARDS
SOUTH FLORIDA. GOES EAST SATELLITE OBSERVATIONS SHOW BUILDING
CUMULUS COVERAGE OVER THE STRAITS OF FLORIDA. TONIGHT, THERE ARE A
COUPLE OF CHANGES TO EXPECT. HURRICANE ISAIAS WILL MOVE FURTHER
FROM THE FLORIDA KEYS, WHICH WILL ALLOW BREEZES TO SLACKEN ACROSS
THE WESTERN WATERS. THE REGION OF SINKING AIR GENERATED BY THE
HURRICANE WILL ALSO FOLLOW THE STORM. SHOWER COVERAGE IS EXPECTED
TO INCREASE WHEN THE DRIER AIR ALOFT SHIFTS AWAY. THE FIRST HALF
OF THE UPCOMING WEEKEND LOOKS RAINY, SO BRACE FOR SHOWERS AND
THUNDERSTORMS.
THERE ARE A COUPLE OF FEATURES TO MONITOR FOR NEXT WEEK. FIRST,
HIGH PRESSURE IS EXPECTED TO BUILD OVER THE SOUTHEASTERN US AFTER
MAJOR HURRICANE ISAIAS MOVES NORTH AND TRANSITIONS INTO A MID
LATITUDE SYSTEM. A FRONT EXTENDING FROM THE FORMER HURRICANE IS
EXPECTED TO MOVE SOUTH AND STALL NEAR THE FLORIDA KEYS EARLY NEXT
WEEK. WHILE A TEMPERATURE CHANGE IS LESS LIKELY, DEW POINTS MAY BE
ABLE TO DECREASE TOWARDS THE LOWER TO MID 70S BY MID WEEK. MEAN
LAYER WINDS WILL NOT REMAIN NORTHEASTERLY, AND BY NEXT FRIDAY WE
MAY BE BACK IN A MOIST PATTERN ACROSS THE KEYS. CHECK BACK AGAIN
OVER THE WEEKEND, BECAUSE ANY FORECAST IN THE WAKE OF A MAJOR
HURRICANE WILL BE PRONE TO MORE UNCERTAINTY THAN USUAL. FOR NOW,
TAKE PRECAUTIONS WHERE NECESSARY!
MARINE
ISSUED AT 315 PM EDT FRI OCT 9 2026
SMALL CRAFT SHOULD EXERCISE CAUTION UNTIL WINDS DECREASE FOR THE
OUTER GULF WATERS AND THE WESTERN STRAITS OF FLORIDA DUE TO
ELEVATED WINDS AND SWELL GENERATED BY MAJOR HURRICANE ISAIAS. A
SMALL CRAFT ADVISORY WAS REQUIRED FOR THE WESTERNMOST WATERS THIS
MORNING, BUT WINDS HAVE SLACKENED AS THE HURRICANE MOVED FURTHER
NORTH. BREEZES ACROSS THE REEF HAVE STABILIZED AS GENTLE TO
MODERATE SOUTHEASTERLIES WITH PERIODS OF MODERATE TO FRESH GUSTS.
FROM SYNOPSIS: MAJOR HURRICANE ISAIAS IS FORECAST TO MAKE LANDFALL
IN NORTHERN FLORIDA TONIGHT. ELEVATED SWELLS GENERATED BY THE
HURRICANE WILL PERSIST THROUGH THE FLORIDA STRAITS AND THE OUTER
GULF WATERS THROUGH THE FIRST HALF OF THE WEEKEND. BREEZES ARE ON
TRACK TO SLACKEN WHILE HURRICANE ISAIAS MOVES NORTH. MEANWHILE, A
PLUME OF MOISTURE WILL MOVE NORTH FROM EASTERN CUBA TONIGHT AND
INCREASE SHOWER AND THUNDERSTORM CHANCES. BREEZES WILL BE ABLE TO
SLACKEN DURING THE FIRST HALF OF THE WEEKEND. NEXT WEEK, EXPECT
BREEZES TO WAX AND WANE AS HIGH PRESSURE DEVELOPS OVER THE
SOUTHEASTERN UNITED STATES.
AVIATION
(18Z TAFS)
ISSUED AT 315 PM EDT FRI OCT 9 2026
VFR CONDITIONS WILL PREVAIL AT EYW AND MTH FOR THE UPCOMING TAF
PERIOD. SHRA NEAR THE TERMINALS WILL BECOME MORE LIKELY TONIGHT AS
MAJOR HURRICANE ISAIAS MOVES FURTHER NORTH. NEAR SURFACE WINDS
WILL SLACKEN TONIGHT, BUT GUSTS AND ELEVATED CROSSWINDS WILL BE A
CONCERN UNTIL TOMORROW MORNING. CLOUD COVERAGE WILL INCREASE
DURING THE EVENING, BUT MVFR TO IFR CONDITIONS ARE NOT EXPECTED
OUTSIDE OF NEARBY SHRA.
CLIMATE
ON THIS DAY IN 2009, THE DAILY RECORD WARM LOW TEMPERATURE OF 84F
WAS RECORDED IN KEY WEST. TEMPERATURE RECORDS FOR KEY WEST DATE
BACK TO 1872. ON THIS DAY IN 2009, THE DAILY RECORD WARM LOW
TEMPERATURE OF 83F WAS RECORDED IN MARATHON. TEMPERATURE RECORDS
FOR MARATHON DATE BACK TO 1951.
OF NOTE
AT PENNEKAMP STATE PARK: IN 2011, A RAINFALL OF 11.02" WAS RECORDED.
PRELIMINARY POINT TEMPS/POPS
KEY WEST 80 89 80 89 / 50 40 60 30
MARATHON 81 88 82 88 / 60 30 40 20
KEY WATCHES/WARNINGS/ADVISORIES
FL...NONE.
GM...SMALL CRAFT ADVISORY UNTIL 4 PM EDT THIS AFTERNOON FOR
GMZ033-034- 055-075.
PUBLIC/MARINE/FIRE...AJP
AVIATION/NOWCASTS....AJP
DATA ACQUISITION.....AJP
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