207
FXUS62 KKEY 120849
AFDKEY
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE KEY WEST FL
449 AM EDT WED MAR 12 2025
..NEW DISCUSSION, MARINE, AVIATION
DISCUSSION
ISSUED AT 445 AM EDT WED MAR 12 2025
THE 00Z EVENING SOUNDING AT KEY SAMPLED AN EXTREMELY DRY AND
STABLE AIR MASS ENGULFING THE FLORIDA KEYS. FEATURES OF INTEREST
FROM THIS SAMPLE INCLUDE LESS THAN 10% RELATIVE HUMIDITY ABOVE THE
925 MB ISOBARIC SURFACE ALL THE WAY TO THE TROPOPAUSE, AND AN
IMPRESSIVE 3.5C THERMAL INVERSION IN THE 940-870 MB LAYER JUST
ABOVE THE SURFACE. IT SHOULD COME AS NO SURPRISE THAT KBYX RADAR
IS VOID OF ANY SHOWER ACTIVITY ACROSS THE ENTIRE FORECAST AREA,
AND NIGHTTIME DERIVED SATELLITE IMAGERY IS STRUGGLING TO DETECT
EVEN ISOLATED CLOUD COVER. AS ADVERTISED IN THE KEY LATE EVENING
DISCUSSION, THERE HAS BEEN A SUBTLE NOCTURNAL WIND SURGE IN THE
NORTHERLY FLOW, BUT MAGNITUDES HAVE NOT BEEN ANYTHING TO WRITE
HOME ABOUT.
A RATHER ROUTINE FORECAST IS IN STORE THROUGH THE WEEKEND. ALOFT,
THE FLORIDA KEYS WILL REMAIN UNDER THE INFLUENCE OF LARGE-SCALE
RIDGING, WHICH WILL ONLY GROW IN STRENGTH THROUGH THE WEEKEND.
MEANWHILE, AT THE SURFACE, HIGH PRESSURE CURRENTLY SITUATED IN
THE CENTRAL GULF WILL SLIDE EASTWARD INTO THE WEST-CENTRAL NORTH
ATLANTIC. THIS HIGH WILL MERGE WITH A STRONGER SECONDARY HIGH
DIVING SOUTHWARD FROM EASTERN CANADA THIS WEEKEND. AT THE SAME
TIME, A STRENGTHENING AREA OF LOW PRESSURE WILL PROGRESS
NORTHEASTWARD FROM THE ROCKIES TO THE UPPER MIDWEST. THE
INTERACTION OF THESE FEATURES WILL PROMOTE A BOUT OF ELEVATED
GRADIENT WIND ACROSS THE KEYS BEGINNING FRIDAY NIGHT, LASTING
THROUGH SUNDAY MORNING. FORECAST SOUNDINGS REMAIN BONE-DRY THROUGH
AT LEAST SATURDAY, BEFORE SUBTLE INCREASED BOUNDARY LAYER MOISTURE
COUPLED WITH THE INCREASED FLOW MAY PROMOTE ISOLATED SHOWER
ACTIVITY FOR SATURDAY NIGHT AND SUNDAY.
ALTHOUGH THE STRONG LOW WILL STEER WELL NORTH OF THE FLORIDA
PENINSULA, GLOBAL ENSEMBLE MEAN AND MEMBERS SUPPORT AN ASSOCIATED
COLD FRONT PUSHING THROUGH THE KEYS SOMETIME ON MONDAY. AS IS
OFTEN THE CASE THIS TIME OF YEAR, THERE REMAINS QUITE A BIT
UNCERTAINTY FOR THE EVOLUTION OF THIS FRONTAL PASSAGE, INCLUDING
STRENGTH AND TIMING. REGARDLESS, IN THIS SCENARIO, AT LEAST A
BROKEN LINE OF SHOWERS (SIMILAR TO WHAT WE SAW ON MONDAY
AFTERNOON AND EVENING) IS A PRETTY GOOD BET AS THE FRONT PUSHES
THROUGH ON MONDAY, SUPPORTIVE OF AROUND 20% MEASURABLE RAIN
CHANCES THIS FAR OUT FOR THE KEYS.
TEMPERATURES FOR THE NEXT SEVEN DAYS WILL MODERATE FROM NEAR-
NORMAL VALUES FOR TODAY THROUGH FRIDAY, TO ABOVE NORMAL OVER THE
WEEKEND WHILE THE FLORIDA KEYS REMAIN SITUATED IN THE PRE-FRONTAL
WARM SECTOR, THEN BACK TO NEAR NORMAL IN THE WAKE OF THE FRONT
FOR EARLY NEXT WEEK.
MARINE
ISSUED AT 445 AM EDT WED MAR 12 2025
NO WATCHES, WARNINGS, OR ADVISORIES ARE CURRENTLY IN EFFECT FOR
THE FLORIDA KEYS COASTAL WATERS. FROM SYNOPSIS, HIGH PRESSURE
CENTERED OVER THE CENTRAL GULF WILL SLIDE EASTWARD THROUGH THE
REST OF THE WORK WEEK. LIGHT TO GENTLE BREEZES WILL RESPOND,
VEERING FROM THE NORTH TO NORTHEAST THIS MORNING TO THE SOUTHEAST
BY THURSDAY. A SECOND, STRONGER HIGH WILL BUILD IN THE WESTERN
NORTH ATLANTIC AND INTERACT WITH A DEVELOPING AREA OF LOW PRESSURE
IN THE CENTRAL UNITED STATES, SUPPORTING FRESHENING SOUTHEASTERLY
BREEZES FOR FRIDAY NIGHT THROUGH EARLY SUNDAY. AS THE FRONT
APPROACHES THE KEYS MARINE ZONES LATE SUNDAY, BREEZES WILL ONCE
AGAIN BRIEFLY SLACKEN.
AVIATION
(06Z TAFS)
ISSUED AT 445 AM EDT WED MAR 12 2025
VFR CONDITIONS WILL PERSIST AT EYW AND MTH THROUGH THE TAF PERIOD,
WITH MINIMAL CLOUDS AND NIL RAIN CHANCES. WINDS WILL REMAIN AROUND 5
KNOTS THROUGH THE PERIOD, STARTING FROM THE NORTH AND GRADUALLY
VEERING TO THE NORTHEAST BY SUNRISE BEFORE BECOMING VARIABLE IN THE
EARLY AFTERNOON.
CLIMATE
ON THIS DAY IN 2018, THE DAILY RECORD RAINFALL OF 1.49" WAS OBSERVED
AT KEY WEST, WITH THE DAILY RECORD ALSO SET AT MARATHON WITH 0.93".
RAINFALL RECORDS FOR KEY WEST DATE BACK TO 1871, AND FOR MARATHON TO
1950.
PRELIMINARY POINT TEMPS/POPS
KEY WEST 76 70 80 72 / 0 0 10 10
MARATHON 76 70 79 72 / 0 0 10 10
KEY WATCHES/WARNINGS/ADVISORIES
FL...NONE.
GM...NONE.
PUBLIC/MARINE/FIRE...BT
AVIATION/NOWCASTS....MC
DATA ACQUISITION.....MC
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