Area Forecast Discussion
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000
FXUS62 KKEY 260318
AFDKEY

AREA FORECAST DISCUSSION FOR THE FLORIDA KEYS
NATIONAL WEATHER SERVICE KEY WEST FL
1018 PM EST TUE NOV 25 2014

.DISCUSSION...
.CURRENTLY...
SKIES ARE QUICKLY CLOUDING UP ACROSS THE KEYS...AS KBYX RADAR IS ALSO
SHOWING A BLOSSOMING OF SCATTERED MODERATE TO HEAVY SHOWER ACTIVITY
ACROSS THE KEYS AND NEARSHORE WATERS. SOUTHEAST WINDS HAVE GRADUALLY
DECREASED TO 5 TO 10 KNOT ACROSS THE KEYS IN THE PAST FEW
HOURS...AND ARE EVER SO SLIGHTLY ARE BEGINNING TO TURN SOUTHERLY IN
THEIR CLOCKING MOTION AHEAD OF OUR NEXT FRONT. ALL MODELS SUGGEST THE
PRESENCE OF A DEVELOPING LOW PRESSURE CENTER OVER THE EASTERN GULF
OF MEXICO AT THIS TIME. DATA IS SPARSE IN THAT AREA HOWEVER...AND THE
SATELLITE APPEARANCE OF THIS LOW IS DUBIOUS AT BEST. CURRENT WIND
FIELDS PRESUMABLY ARE OBSCURED BY SHOWER OUTFLOWS...AND MSLP SENSORS
IN THE AREA ARE ERRATIC BUT THE APPEARANCE IS MORE INDICATIVE OF A
SLOWLY DEVELOPING LOW OR PRE-FRONTAL TROUGH. A PRE-FRONTAL BAND OF
SHOWERS AND THUNDERSTORMS IS MOSTLY TRAINING TO THE NORTHEAST ACROSS
THE PORT CHARLOTTE AND SARASOTA COASTLINE...AND EXTENDS SOUTHWEST
INTO THE SOUTHERN GULF OF MEXICO. WARM SECTOR FLOW IS STILL KEEPING
THE KEYS SEASONALLY WARM NEAR 80...AND MOIST WITH DEWPOINTS AROUND
THE MID 70S. EVENING SOUNDING SHOWED AN OVERALL PWAT VALUE OF 2.03
INCHES...WITH MOST MOISTURE FOUND BELOW 600 MB... AND SIGNIFICANT
VEERING IN THE LOWEST LAYERS...GIVING RAPIDLY TO UNIDIRECTIONAL FLOW
ABOVE 950 MB OUT OF THE SOUTHWEST.

.SHORT TERM...
THE MOTION OF THIS QUICKLY-DEVELOPING LOW SHOULD SEE IT RAPIDLY
TRANSIT CENTRAL FLORIDA...AND EJECTED OFF THE JACKSONVILLE
COASTLINE OF THE WESTERN ATLANTIC BY 06-09Z. REGARDLESS OF THE
INTENSITY OF THIS SURFACE LOW OR ITS MOTION...THERE IS VERY LITTLE
DOUBT THAT A ROBUST COLD FRONT WILL BUILD IN BEHIND IT...THEN WILL
PUSH SOUTH ACROSS THE EASTERN GULF. THIS FRONT IS SET TO TRANSIT
DOWN THE WEST COAST OF FLORIDA AND APPROACH THE KEYS BY MID MORNING
WEDNESDAY. MOISTURE...AND INSTABILITY WITH SOME MODEST ISOTROPIC
LIFTING ARE ALL EXPECTED TO BE PRESENT AHEAD OF THIS FRONT OVERNIGHT.
DURING ITS PASSAGE ACROSS THE KEYS...MAINLY BETWEEN 14Z AND
16Z...EXPECT THAT ITS RAPID MOTION WILL INSPIRE SOME SHOWER AND
THUNDERSTORM ACTIVITY TO FORM ALONG ITS LEADING EDGE. TOTAL COVERAGE
WILL BE BE ENTIRELY DEPENDENT UPON THE INTEGRITY OF LOW LEVEL
CONVERGENCE AND CONFLUENCE FIELDS HOWEVER. A CASE CAN BE MADE FOR BOTH
LIKELY SHOWERS WITH THE FRONTAL PASSAGE TOMORROW...BUT WILL HOLD OFF
ON UPDATING THE FORECAST PENDING FURTHER CLARITY OVERNIGHT. AS IT
STANDS...ONLY MINOR MODIFICATIONS WERE REQUIRED FOR THE OVERNIGHT
PUBLIC FORECAST AND GRIDS...WITH NO CHANGES REQUIRED FOR PERIODS
THEREAFTER.

&&

.MARINE...
WINDS OVERNIGHT WILL BE 5 TO 15 KNOTS ACROSS THE KEYS...WITH THE
EARLIEST WIND INCREASES EXPECTED OUT OF THE SOUTHWEST OVER THE GULF
WATERS AFTER 9Z. THIS FRONTAL PASSAGE IS EXPECTED TO BE DIFFERENT
THAN THE PREVIOUS FRONTS THIS SEASON...WITH A RAPID SHIFT AND
INCREASE IN WINDS EXPECTED ACROSS THE ISLAND CHAIN MAINLY BETWEEN 11
AND 16Z. SEAS SHOULD RESPOND IN-KIND TO THE WINDS...BUILDING RAPIDLY
TO AROUND 10 FEET IN THE DEEPEST PARTS OF THE SOUTHEASTERN GULF BY
15Z...WITH THESE SWELLS SPREADING ACROSS THE STRAITS BY LATE
AFTERNOON. A PROLONGED PERIOD FRESH TO STRONG WINDS WILL BUILD IN
BEHIND THIS FRONT...BRINGING SCA CONDITIONS TO THE COASTAL WATERS
THROUGH AT LEAST THURSDAY.

&&

.AVIATION...
VFR CONDITIONS WILL PREVAIL AT BOTH THE KEY WEST AND MARATHON
TERMINALS OVERNIGHT WITH SOUTHEAST WINDS FROM 5 TO 10
KNOTS...BECOMING SOUTHWESTERLY TOWARDS DAYBREAK. A COLD FRONT WILL PUSH
THROUGH THE KEYS WEDNESDAY MORNING AFTER DAYBREAK. THIS WILL RESULT
IN WINDS SHIFTING TO NORTHWEST AND INCREASING TO AROUND 25 KNOTS AND
GUSTY. TEMPORARY MVFR CEILINGS WILL BE LIKELY PERSIST FOR SEVERAL
HOURS AFTER THE FRONT PUSHES THROUGH. THIS IS REFLECTED IN THE
TERMINAL FORECASTS WITH TEMPO GROUPS AT BOTH TERMINALS. THE MVFR
CONDITIONS SHOULD ABATE LATE MORNING INTO THE EARLY AFTERNOON WITH
VFR CEILINGS AROUND FL050 PREVAILING THROUGH THE REMAINDER OF
WEDNESDAY.

&&

.KEY WATCHES/WARNINGS/ADVISORIES...
FL...NONE.
GM...NONE.
&&

$$

PUBLIC/MARINE.........MSB
AVIATION/NOWCASTS.....DEVANAS
DATA COLLECTION.......FLING

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