104
FXUS62 KKEY 091523
AFDKEY
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE KEY WEST FL
1123 AM EDT WED JUL 9 2025
..NEW DISCUSSION, MARINE, AVIATION
DISCUSSION
ISSUED AT 1100 AM EDT WED JUL 9 2025
SURFACE ANALYSIS DEPICTS AN EXPANSIVE AREA OF SURFACE HIGH
PRESSURE ACROSS THE NORTH ATLANTIC. LOW- AND MID-LEVEL VORTICITY
ANALYSIS PLACES A POSITIVELY TILTED INVERTED TROUGH EXTENDING FROM
THE WESTERN BAHAMAS SOUTHWESTWARD TOWARDS THE WESTERN CARIBBEAN
SOUTH OF CUBA. THE 12Z MORNING SOUNDING AT KEY SUPPORTS THIS
FEATURE, WITH MODESTLY FALLING GEOPOTENTIAL HEIGHTS BETWEEN
900-500 MB. THE SOUNDING ALSO DEPICTED SIGNIFICANT DRY AIR BETWEEN
800-500 MB, ALTHOUGH RECENT SATELLITE-DERIVED MOISTURE
OBSERVATIONS SUGGEST A WELL-DEFINED SLEW OF MOISTURE IS QUICKLY
APPROACHING THE KEYS. ASSOCIATED WITH THE MOISTURE SURGE, KBYX
DOPPLER RADAR HAS BEEN DETECTING SCATTERED SHOWERS WITH ISOLATED,
BRIEFLY STRONGER EMBEDDED THUNDERSTORMS ACROSS THE COASTAL WATERS
MAINLY SOUTH OF THE ISLAND CHAIN. OUTSIDE OF THE UPPER KEYS, MOST
ISLAND COMMUNITIES HAVE REMAINED DRY SO FAR TODAY.
FOR THE BALANCE OF THIS AFTERNOON, SHOWER AND THUNDERSTORM
ACTIVITY SHOULD GRADUALLY WANE OVER THE NEXT COUPLE HOURS ACROSS
THE STRAITS AND THE MIDDLE AND UPPER KEYS. AVAILABLE CONVECTIVE
ALLOWING MODEL (CAM) GUIDANCE, INCLUDING OUR OFTEN REFERENCED HRRR
MODEL, SUPPORTS THIS EVOLUTION. VISIBLE SATELLITE OBSERVATIONS
DEPICT A WELL- DEFINED CIRRUS DECK STREAMING NORTHEASTWARD TOWARDS
THE LOWER KEYS AWAY FROM THE CONVECTION IN THE STRAITS. THIS MAY
LIMIT (OR AT LEAST DELAY) WHAT WOULD NORMALLY BE A FAVORABLE
ENVIRONMENT FOR A LOWER KEYS ISLAND CLOUD LINE EVENT. THE IN-HOUSE
WATERSPOUT INDEX BASED ON THE MORNING KEY SOUNDING WAS WELL ABOVE
CLIMATOLOGY, SUPPORTIVE OF THE POSSIBLE ISLAND CLOUD LINE
FORMATION AND ASSOCIATED WATERSPOUT OUTBREAKS. WEIGHING IN ALL OF
THIS, ELECTED TO PUNT ANY CHANGES TO THE INHERITED ONCE-PER-DAY
FULL FORECAST PACKAGE.
MARINE
ISSUED AT 1100 AM EDT WED JUL 9 2025
NO WATCHES, WARNINGS, OR ADVISORIES ARE CURRENTLY IN EFFECT IN THE
FLORIDA KEYS WATERS. FROM SYNOPSIS, A NORTH ATLANTIC AREA OF
SURFACE HIGH PRESSURE WILL MAINTAIN GENTLE TO MODERATE BREEZES
EASTERLY ACROSS THE FLORIDA KEYS THROUGH THIS AFTERNOON. AN
EASTERLY TROPICAL WAVE WILL CONTINUE TO APPROACH THE KEYS THIS
AFTERNOON AND TONIGHT. IN CONJUNCTION WITH VEERING WINDS, SHOWER
AND THUNDER COVERAGE WILL BECOME ELEVATED TONIGHT, LASTING THROUGH
THE END OF THE WORK WEEK. A RETURN TO NEAR-NORMAL RAIN AND
THUNDER CHANCES IS EXPECTED FOR NEXT WEEKEND.
AVIATION
(15Z TAFS)
ISSUED AT 1100 AM EDT WED JUL 9 2025
WHILE VFR CONDITIONS WILL PREVAIL AT BOTH ISLAND TERMINALS THROUGH
12Z THURSDAY MORNING, A SURGE OF MOISTURE WILL SUPPORT VICINITY
SCATTERED SHOWERS AND ISOLATED THUNDERSTORMS LATE THIS MORNING
THROUGH THE EARLY AFTERNOON AT MTH. THEREAFTER, AN ISLAND CLOUD
LINE MAY FORM IN THE VICINITY OF EYW LATER THIS AFTERNOON,
SUPPORTING ANOTHER ROUND OF NEARBY SHOWERS AND POSSIBLE
THUNDERSTORMS. HAVE INCLUDED WINDOWS OF VCSH IN THE TAFS FOR NOW,
GIVEN THE UNCERTAINTY IN COVERAGE AND EVOLUTION, WITH POSSIBLE
SUB-VFR IMPACTS AT THE TERMINALS TO BE LEFT FOR POSSIBLE LATER TAF
AMENDMENTS THIS AFTERNOON.
PRELIMINARY POINT TEMPS/POPS
KEY WEST 91 82 91 82 / 30 30 50 40
MARATHON 89 81 89 82 / 40 30 50 50
KEY WATCHES/WARNINGS/ADVISORIES
FL...NONE.
GM...NONE.
PUBLIC/MARINE/FIRE...BT
AVIATION/NOWCASTS....BT
DATA ACQUISITION.....BT
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