431
FXUS62 KKEY 290831
AFDKEY
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE KEY WEST FL
431 AM EDT WED JUL 29 2026
..NEW DISCUSSION, MARINE, AVIATION
KEY MESSAGES
- A REVERSE CLOUD LINE IS POSSIBLE TODAY DUE TO SOUTHWESTERLY FLOW.
THIS FLOW WILL TEND TO FAVOR WATERSPOUT DEVELOPMENT. BOATERS
ARE ENCOURAGED TO KEEP AN EYE ON THE SKY IF VENTURING OUT.
- SMALL CRAFT SHOULD EXERCISE CAUTION OFFSHORE OF THE UPPER KEYS
DUE TO A BRIEF FRESHENING OF WINDS AGAIN THIS AFTERNOON. BREEZES
WILL GRADUALLY SLACKEN OVERNIGHT.
- HEAT INDICES MAY APPROACH 105 TO 110 DEGREES EACH AFTERNOON FOR
SOME FLORIDA KEYS ISLAND COMMUNITIES, ESPECIALLY IN THE UPPER
KEYS.
DISCUSSION
ISSUED AT 431 AM EDT WED JUL 29 2026
CIMSS PRODUCTS SHOWS THE KEYS CONTINUE TO REMAIN IN BETWEEN TWO
RIDGES. ONE RIDGE CONTINUES TO DOMINATE THE NORTH ATLANTIC WHILE
THE OTHER ONE REMAINS OVER THE SOUTH-CENTRAL UNITED STATES. MEAN
LAYER TROUGHING REMAINS IN PLACE ALONG THE EASTERN SEABOARD
EXTENDING SOUTHWARD TO JUST EAST OF FLORIDA. AT THE SURFACE, A LOW
PRESSURE SYSTEM CONTINUES TO DEVELOP OFF THE DEL-MAR-VA COASTLINE
ALONG WITH HIGH PRESSURE OVER THE WESTERN NORTH ATLANTIC. THE
KEYS REMAIN ON WESTERN FRINGE OF THE HIGH PRESSURE CENTERED OVER
THE WESTERN NORTH ATLANTIC WITH A SURFACE TROUGH OVER FLORIDA.
MARINE OBSERVATION PLATFORMS SURROUNDING THE ISLAND CHAIN ARE
RECORDING SOUTHWEST TO WEST BREEZES NEAR 10 KNOTS. KBYX RADAR HAS
BEEN QUIET MOST OF THE NIGHT WITH A FEW ISOLATED SHOWERS, MOSTLY
OVER FLORIDA BAY, DEVELOPING OVER THE LAST HOUR OR TWO. GOES 19
NIGHTTIME MICROPHYSICS IMAGERY SHOWS PARTLY CLOUDY SKIES
THROUGHOUT THE KEYS WITH A MIXTURE OF LOW AND HIGH LEVEL CLOUDS.
TEMPERATURES ALONG THE ISLAND CHAIN ARE IN THE LOWER TO MID 80S
AND DEW POINTS ARE IN THE MID 70S.
FORECAST
THE FORECAST FOR THE NEXT WEEK OR MORE IS EXPECTED TO REMAIN
FAIRLY BENIGN. HIGH PRESSURE WILL OCCASIONALLY NUDGE INTO THE
REGION INFLUENCING THE BREEZES ACROSS THE AREA. OTHERWISE, A COL
REGION IS EXPECTED TO BE THE DOMINANT FEATURE, ESPECIALLY FOR LATE
WEEK INTO THE WEEKEND. A COL REGION IS USUALLY AN AREA OF
QUIESCENT WEATHER CONDITIONS IN BETWEEN THE LARGER SCALE SYNOPTIC
WEATHER SYSTEMS. THEREFORE, WHILE SOUTHWEST TO WEST BREEZES ARE
EXPECTED TODAY, BRIEFLY BECOMING MODERATE TO FRESH THIS AFTERNOON
IN THE UPPER KEYS, A PERIOD OF LIGHT AND VARIABLE BREEZES IS
POSSIBLE LATE WEEK AND INTO THE WEEKEND. MUCH DRIER AIR HAS
INFILTRATED THE KEYS WHEN COMPARED TO 24 HOURS AGO. A REVERSE
CLOUD LINE IS POSSIBLE TODAY AND AGAIN ON THURSDAY AS
SOUTHWESTERLY FLOW REMAINS ACROSS THE KEYS. IT REMAINS TO BE SEEN
JUST HOW MUCH MOISTURE IS PRESENT TO DETERMINE HOW VIGOROUS ANY
CLOUD LINE BECOMES. IF A MATURE CLOUD LINE CAN DEVELOP,
WATERSPOUTS WILL BE POSSIBLE. HOWEVER, THERE IS THE CHANCE THAT IT
ENDS UP BEING TOO DRY TODAY AND TOMORROW FOR THE CLOUD LINE TO
REALLY GET GOING. WE WILL SEE WHAT HAPPENS. A SLIGHT CHANCE OF
SHOWERS AND THUNDERSTORMS IS IN PLACE FOR TODAY AND THURSDAY AS A
RESULT. OUTSIDE OF ANY RAIN CHANCES, THE MAIN STORY WILL BE THE
HEAT. DAYTIME HIGHS ARE EXPECTED TO BE NEAR 90 DEGREES WITH SOME
LOWER 90 DEGREE READINGS WITH DEW POINTS IN THE MID TO UPPER 70S.
THIS WILL PUSH THE HEAT INDEX VALUES TO 105 TO 110 DEGREES AT
TIMES, ESPECIALLY FOR SOME UPPER KEYS COMMUNITIES. OVERNIGHT LOWS
ALSO WON'T PROVIDE MUCH RELIEF IN THE LOWER TO PERHAPS MID 80S.
MARINE
ISSUED AT 431 AM EDT WED JUL 29 2026
SMALL CRAFT SHOULD EXERCISE CAUTION FOR BRIEFLY INCREASING WINDS
ONCE AGAIN ACROSS THE NEARSHORE WATERS ADJACENT TO THE UPPER KEYS
AS WELL AS THE EASTERN STRAITS OF FLORIDA. OTHERWISE, THERE ARE NO
WATCHES, WARNINGS, OR ADVISORIES IN EFFECT ACROSS THE FLORIDA KEYS
COASTAL WATERS. FROM SYNOPSIS, TROUGHING COMBINED WITH THE
WESTERN PERIPHERY OF AN ATLANTIC SURFACE RIDGE WILL MAINTAIN
SOUTHWEST TO WEST BREEZES ACROSS THE KEYS TODAY. LIGHT TO GENTLE
BREEZES WILL FRESHEN TO MODERATE TO FRESH BREEZES THIS AFTERNOON,
ESPECIALLY ACROSS THE ADJACENT NEARSHORE AND OFFSHORE WATERS TO
THE UPPER KEYS. ALSO, A REVERSE CLOUD LINE IS POSSIBLE TODAY WHICH
MAY RESULT IN WATERSPOUT FORMATION. BREEZES GRADUALLY SLACKEN
OVERNIGHT THROUGH THURSDAY NIGHT AS WEAK NEBULOUS FLOW TAKES OVER.
A COL REGION SETS UP FOR LATE WEEK INTO THE WEEKEND RESULTING IN
A POTENTIAL PERIOD OF VARIABLE BREEZES.
AVIATION
(06Z TAFS)
ISSUED AT 431 AM EDT WED JUL 29 2026
VFR CONDITIONS ARE EXPECTED TO PERSIST AT BOTH EYW AND MTH
TERMINALS THROUGH THE TAF PERIOD. NEAR SURFACE WINDS WILL REMAIN
MOSTLY SOUTHWEST TO WEST THROUGH THE PERIOD. MUCH DRIER AIR HAS
MOVED OVER THE KEYS COMPARED TO 18-24 HOURS AGO. HOWEVER, JUST
ENOUGH MOISTURE MAY BE PRESENT TO INFLUENCE A CLOUD LINE TODAY.
THIS WILL BE A REVERSE CLOUD LINE SINCE THE FLOW IS SOUTHWESTERLY.
DUE TO THIS A SLIGHT CHANCE OF SHOWER OR A THUNDERSTORM IS
POSSIBLE. HOWEVER, GIVEN THE UNCERTAINTY IN TIMING AND PLACEMENT
AND IF THIS EVEN DEVELOPS, VCSH WAS NOT INCLUDED IN THE TAF.
CLIMATE
ON THIS DAY IN 2009, THE DAILY RECORD WARM LOW TEMPERATURE OF 86F
WAS RECORDED IN KEY WEST. TEMPERATURE RECORDS FOR KEY WEST DATE
BACK TO 1872.
ON THIS DAY IN 2023, THE DAILY RECORD WARM LOW TEMPERATURE OF 84F
WAS RECORDED IN MARATHON. TEMPERATURE RECORDS FOR MARATHON DATE
BACK TO 1951.
PRELIMINARY POINT TEMPS/POPS
KEY WEST 90 83 91 83 / 10 0 10 0
MARATHON 90 83 91 83 / 10 0 10 0
KEY WATCHES/WARNINGS/ADVISORIES
FL...NONE.
GM...NONE.
PUBLIC/MARINE/FIRE...MJV
AVIATION/NOWCASTS....MJV
DATA ACQUISITION.....MJV
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