Area Forecast Discussion
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000
FXUS62 KKEY 060139
AFDKEY

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE KEY WEST FL
939 PM EDT THU MAY 5 2016

.DISCUSSION...IN THE MID AND UPPER LEVELS...700-200 MB...LATEST
AVAILABLE IR IMAGERY AS OF 900 PM...OVERLAID WITH MODEL STREAMLINE
ANALYSIS DEPICT A VERY ROBUST FULL LATITUDINAL LATE SEASON COLD CORE
TROUGH ACROSS THE EASTERN SEABOARD...WITH AN ASSOCIATED MIDDLE LEVEL
COLD CORE LOW PRESSURE SYSTEM OVER THE NORTH CAROLINA MOUNTAINS.
WATER VAPOR DELINEATES VERY DRY AIR IN THE MIDDLE AND UPPER LEVELS IN
THIS DEEP CYCLONIC FLOW OVER EXTREME SOUTH FLORIDA AND THE
KEYS...WITH A 75 TO 100 KNOT UPPER JET AT 250 MB MOVING OVER THE
KEYS.

AT THE SURFACE AND IN THE LOWER TO MIDDLE LEVELS...SURFACE TO 700
MB...LATEST IR IMAGERY OVERLAID WITH LATEST AVAILABLE LAND AND
MARINE SURFACE OBSERVATIONS AND ANALYSIS AS OF 900 PM DETAIL AN
ATTENDANT COLD FRONT SWINGING UNUSUALLY FAR SOUTHWARDS FOR THIS TIME
OF YEAR AND BISECTING THE EASTERN HALF OF CUBA FROM 996 MB LOW
PRESSURE EAST OF THE DELMARVA PENINSULA. LAST EVENINGS 00Z SOUNDING
ILLUSTRATED A VERY DRY AIR MASS IN PLACE WITH A MODERATE TO STRONG
NORTHWEST TO NORTH FLOW JUST OFF OF THE SURFACE UP TO 700 MB AND
BECOMING DUE WESTERLY...WITH TOTAL COLUMNAR PWAT(PRECIPITABLE WATER)
ONLY AT ABOUT .70 INCHES.

.CURRENTLY...SKIES ACROSS THE ISLANDS ARE MOSTLY CLEAR. TEMPERATURES
OVER THE ISLANDS ARE IN THE MIDDLE 70S WITH COMFORTABLE DEWPOINTS
AROUND 60 DEGREES. C-MAN STATIONS ARE RECORDING WEST TO NORTHWEST
WINDS NEAR 20 KNOTS IN FLORIDA BAY AND 15 TO 20 KNOTS AND GUSTY IN
HAWK CHANNEL AND THE EASTERN FLORIDA STRAITS OUT 60 NM FROM OCEAN
REEF TO CRAIG KEY...WHEREAS WINDS IN THE REST OF THE MARINE DISTRICT NOT
DOWNWIND OF THE COOL DRY AIR OFF THE PENINSULA ARE WEST TO NORTHWEST
AT 10 TO 15 KNOTS AND GUSTY.

.SHORT TERM...WITHIN THE UNUSUALLY DEEP NORTH TO SOUTH ORIENTED
TROUGH...A PIECE OF ENERGY IS DIVING SOUTHWARDS ACROSS THE EASTERN
GULF OF MEXICO...RESULTING IN A REINFORCEMENT OF UNSEASONABLY DRY AIR
FOR THIS TIME OF YEAR BY ANOTHER APPROACHING LOWER/LEVEL SURFACE
TROUGH. LATEST AVAILABLE MODEL FORECAST SOUNDINGS DO ILLUSTRATE THAT
AS THIS NEXT TROUGH/WEEK COOL FRONT APPROACHES BY 12Z IN THE
MORNING...SLIGHT MOISTENING IN THE SURFACE TO 700 MB LAYER WILL
RESULT IN PWAT CLIMBING ABOVE 1.00 INCHES AHEAD OF THIS FEATURE
BETWEEN 0600Z AND 1200Z...AND GIVEN THE INSTABILITY ALOFT FROM THE
UPPER IMPULSE...A BROKEN LINE OF FAST MOVING LIGHT SHOWERS SHOULD
MOVE IN ACROSS THE ISLANDS BETWEEN 06Z AND 12Z. THIS IS SHOWN IN THE
MESOSCALE WRF...AND A FEW HUNDRETHS OF AN INCH OF RAINFALL ARE NOT
OUT OF THE QUESTION. NO CHANGES WILL BE MADE.

&&

.MARINE...THE NEXT WEAK TROUGH IS PROGGED TO MOVE ACROSS THE WATERS
TOWARDS SUNRISE...BUT AHEAD OF IT...DENSITY BLOW UPSTREAM OF THE
UPPER FLORIDA KEYS...ARE RESULTING IN FRESH BREEZES OVER FLORIDA
BAY AND THE ADJOINING HAWK CHANNEL AND EASTERN FLORIDA STRAITS.
BEHIND THE TROUGH...WINDS WILL BECOME NORTHWEST TO NORTH AND GENTLE
TO MODERATE ACROSS ALL WATERS TOWARDS MORNING.

&&

.AVIATION...VFR CONDITIONS EXPECTED AT BOTH THE KEY WEST AND MARATHON
ISLAND TERMINALS. A BROKEN LINE OF WEAK FAST MOVING SHOWERS COULD
RESULT IN SHORT LIVED MVFR VISIBILITY...WITH MVFR/VFR CIGS. WINDS
WILL VEER FROM 320 DEGREES AOA 10 KNOTS TO 340-350 DEGREES AOA 12
KNOTS TOWARDS DAYBREAK...THEN BECOMING GUSTY AFTER SUNRISE.


&&

.KEY WATCHES/WARNINGS/ADVISORIES...
FL...NONE.
GM...SMALL CRAFT ADVISORY UNTIL 500 AM EDT FRI MORNING
FOR GMZ031-042-052-072.

&&

$$

PUBLIC/MARINE.........FUTTERMAN
AVIATION/NOWCASTS.....FUTTERMAN
DATA COLLECTION.......CHESSER

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