199
FXUS62 KKEY 121546
AFDKEY
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE KEY WEST FL
1146 AM EDT FRI SEP 12 2025
..NEW DISCUSSION, MARINE, AVIATION
DISCUSSION
ISSUED AT 1145 AM EDT FRI SEP 12 2025
A MOIST AND UNSTABLE ENVIRONMENT IS PRESENT ACROSS THE FLORIDA
KEYS THIS MORNING WITH ONGOING AND DEVELOPING SHOWERS AND
THUNDERSTORMS. BEFORE SUNRISE, KBYX DETECTED A GROWING CLUSTER OF
SHOWERS AND EMBEDDED THUNDERSTORMS IN THE DEEP GULF WATERS. A
NEBULOUS FLOW KEPT THE COMPLEX RELATIVELY CONTAINED TO THE AREA
FOR A FEW HOURS, BUT IT EVENTUALLY SCRAPPED OVER THE WESTERN EDGE
OF THE LOWER KEYS BRINGING GUSTY WINDS AND LIGHTNING STRIKES.
USUALLY THAT WOULD BE IT FOR THE MORNING ACTIVITY AS THIS CLUSTER
DIMINISHES, BUT MORE CONVECTION IS BUBBLING UP BOTH ALONG THE
OUTFLOW BOUNDARIES IN THE STRAITS OF FLORIDA AND BACK IN THE DEEP
GULF WATERS. NEEDLESS TO SAY, THE ATMOSPHERE IS QUITE ENERGIZED AT
THE MOMENT WITH PRECIPITATION FORMING DESPITE LIGHT GENERALLY
NORTHERLY BREEZES (OCCASIONALLY VARIABLE) ACROSS OUR REEF
OBSERVATION STATIONS OUTSIDE OF CONVECTION. EXTRA CLOUD COVER
ALOFT HAS TEMPERATURES A TOUCH COOLER THAN YESTERDAY AT THIS TIME
AS THEY REPORT BACK IN THE MID 80S.
THIS MORNING'S ACTIVE MODE LOOKS TO BE A HARBINGER OF WEATHER TO
COME IN THE SHORT TERM FORECAST. OUR 12Z KKEY BALLOON SOUNDING
OBSERVED YET ANOTHER PW ABOVE THE 90TH PERCENTILE ALONG WITH A
RESPECTABLE ML CAPE VALUE ~1750 J/KG. CIMSS MIMIC PW SHOWS A SHARP
GRADIENT OF VALUES ACROSS CENTRAL FLORIDA NOTATING THE APPROXIMATE
LOCATION OF A STALLED FRONTAL BOUNDARY. TO ITS SOUTH, VALUES
GREATER THAN 2 INCHES ARE PLENTIFUL INCLUDING ACROSS OUR AREA.
MEANWHILE, UPPER LEVEL TROUGHING IS MEANDERING EAST THROUGH THE
GULF SLOTTING SOUTH FLORIDA INTO AN AREA FAVORABLE FOR CONVECTIVE
DEVELOPMENT. THUS WE EXPECT REPEAT OF STORMS ON SOUTH FLORIDA
EJECTING BOUNDARIES INTO OUR WATERS TO SPARK ANOTHER ROUND OF
STORMS LATER TODAY. THEN TOMORROW, WE LOOK TO REPEAT THE PROCESS
OVER WITH NOCTURNAL PRECIPITATION IN THE MORNING HOURS AND LIKELY
MORE INDUCED FROM MAINLAND OUTFLOW BOUNDARIES. THE ONLY LIMITING
FACTOR IS THE LIGHTER WINDFIELD FOUND SOUTH OF THE FRONT, ALTHOUGH
THIS MORNING HAS ALREADY PROVED THAT DOES NOT SEEM TO BE MUCH OF
AN ISSUE. WILL CONTINUE TO HOLD 70 POPS OVER THE NEXT FEW PERIODS
WITH NO CHANGES TO THE FORECAST REQUIRED AT THIS TIME.
MARINE
ISSUED AT 1145 AM EDT FRI SEP 12 2025
NO WATCHES, WARNINGS, OR ADVISORIES ARE CURRENTLY IN EFFECT FOR
THE COASTAL WATERS OF THE FLORIDA KEYS. FROM SYNOPSIS, A WEAK
SURFACE TROUGH STRUNG ACROSS SOUTH FLORIDA AND THE KEYS WILL SHIFT
SOUTHWARDS INTO THE STRAITS OVER THE NEXT COUPLE OF DAYS AS HIGH
PRESSURE EXPANDS SOUTHWARD OUT OF THE SOUTHEASTERN UNITED STATES.
THE WET PATTERN WILL CONTINUE WITH RAIN CHANCES LIKELY TRENDING
HIGHER DUE TO THE MIGRATING TROUGH. CONFIDENCE IS VERY LOW WITH
RESPECT TO THE WIND FORECAST. THE TROUGH IS EXPECTED TO STALL NOT
TOO FAR OFF TO THE SOUTH AND THE FRESHER BREEZES ASSOCIATED WITH
THE RIDGE FURTHER NORTH SHOULD REMAIN JUST OUT OF OUR AREA THROUGH
THE WEEKEND. AS A RESULT, WINDS IN THE NEAR TERM WILL BE LIGHT,
OFTEN VARIABLE. HOWEVER, SHOWERS AND THUNDERSTORMS WILL DELIVER
LOCALIZED HIGHER WINDS AND SEAS. GENTLE TO MODERATE NORTHEAST TO
EASTERLY BREEZES ARE EXPECTED TO BUILD IN AS THE HIGH FINALLY IS
ABLE TO SPREAD DOWN INTO OUR AREA. WITH THAT SAID, UNCERTAINTY
REMAINS CONSIDERABLE.
AVIATION
(15Z TAFS)
ISSUED AT 1145 AM EDT FRI SEP 12 2025
VFR CONDITIONS ARE EXPECTED TO PREVAIL FOR THE NEXT FEW HOURS OR
SO BEFORE ADDITIONAL SHOWERS AND THUNDERSTORMS PULSE UP IN THE
VICINITY OF THE ISLAND CHAIN. EXACT TIMING CONTINUES TO BE
UNCERTAIN, SO A GENERAL VCSH CONTINUES IN THE TAFS FOR NOW. SUB-
VFR CONDITIONS WILL BE ADDRESSED VIA AMENDMENTS, POTENTIALLY
FREQUENT, AS NECESSARY DURING THIS PERIOD. STORMS SHOULD THEN AGAIN
WANE BY LATE THIS AFTERNOON OR EVENING THROUGH THE REMAINDER OF THE
TAF PERIOD, BEFORE ADDITIONAL STORM DEVELOPMENT ONCE AGAIN OCCURS.
CLIMATE
IN 2020, THE DAILY RECORD RAINFALL OF 9.37" WAS RECORDED AT KEY WEST
INTERNATIONAL AIRPORT. THIS HIGH DAILY RAINFALL VALUE WAS ATTRIBUTED
TO TROPICAL STORM SALLY PASSING BY TO THE NORTH OF THE KEYS EARLIER
IN THE DAY, AND THEN CUBAN THUNDERSTORM OUTFLOW SURGING NORTHWARD
ACROSS THE STRAITS OF FLORIDA THAT EVENING. DURING THE LATE EVENING
HOURS, A THUNDERSTORM OVER THE LOWER KEYS PRODUCED 3.98" OF RAINFALL
AT KEY WEST INTERNATIONAL AIRPORT IN ONE HOUR. THIS LED TO NUMEROUS
REPORTS OF FLOODED STREETS AND STALLED CARS IN KEY WEST, WITH
FLOODING LASTING SEVERAL HOURS. THIS IS THE WETTEST DAY EVER
RECORDED DURING THE MONTH OF SEPTEMBER, TOPPLING 1919'S RECORD OF
7.47" ON SEPTEMBER 10TH, BY ALMOST 2 WHOLE INCHES.
PRELIMINARY POINT TEMPS/POPS
KEY WEST 89 77 89 78 / 70 60 70 60
MARATHON 89 77 87 78 / 70 70 70 60
KEY WATCHES/WARNINGS/ADVISORIES
FL...NONE.
GM...NONE.
PUBLIC/MARINE/FIRE...JAM
AVIATION/NOWCASTS....JAM
DATA ACQUISITION.....JAM
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