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000
FXUS62 KKEY 062012
AFDKEY

AREA FORECAST DISCUSSION FOR THE FLORIDA KEYS
NATIONAL WEATHER SERVICE KEY WEST FL
310 PM EST FRI DEC 6 2013

.DISCUSSION...IN THE MID AND UPPER LEVELS...(700-200 MB)...LATEST
AVAILABLE IR IMAGERY OVERLAID WITH MODEL STREAMLINE ANALYSIS AS OF
200 PM DEPICT THE CENTER OF A DEEP FULL LATITUDINAL POLAR TROUGH
CENTERED NEAR WESTERN NORTH DAKOTA...WITH AN APPROXIMATE 100-150
KNOT SOUTHERN STREAM OF THE JET AT 250 MB MOVING ALONG THE BASE OF
THIS MASSIVE POLAR GYRE FROM NORTHERN OLD MEXICO NORTHEASTWARD INTO
SOUTHERN QUEBEC. CLOSER TO THE KEYS...THE CENTER OF A DEEP AND WARM
ANTICYCLONE IS POSITIONED OVER WESTERN CUBA.

AT THE SURFACE AND IN THE LOWER LEVELS...SURFACE TO 700 MB...LATEST
AVAILABLE IR IMAGERY OVERLAID WITH SURFACE LAND AND MARINE
OBSERVATIONS AS WELL AS ANALYSIS AS OF 200 PM...CONTINUE TO DETAIL
THE CENTER OF THE ARCTIC 1048 MB SURFACE ANTICYCLONE OVER SOUTHERN
ALBERTA. OF COURSE...AN ARCTIC COLD FRONT IS WELL OUT AHEAD THE
FEATURE...EXTENDING FROM NOVA SCOTIA SOUTH SOUTHWESTWARD TO THE
WESTERN GULF OF MEXICO. YET CLOSER TO THE KEYS...THE WESTERN
PERIPHERY OF A RELATIVELY WEAKER 1020 MB WESTERN ATLANTIC SURFACE
RIDGE AXIS CURRENTLY POKES WESTWARD TO ACROSS THE SOUTH CENTRAL
FLORIDA PENINSULA FROM THE WEST CENTRAL ATLANTIC.

.CURRENTLY...AS OF 200 PM...DRIER AIR HAS MIXED DOWN THIS AFTERNOON
FROM THE MID LEVELS...ERODING THE REMNANT AM BOUNDARY IN THE WESTERN
FLORIDA STRAITS...WITH VISIBLE SATELLITE IMAGERY DETECTING SOME
CUMULUS OVER THE STRAITS...AND MOSTLY SUNNY SKIES ELSEWHERE.
TEMPERATURES OVER THE ISLANDS HAVE REACHED THE LOWER 80S WITH
DEWPOINTS AROUND 70 DEGREES. AVAILABLE C-MAN STATIONS ALONG THE REEF
HAVE COME DOWN TO NEAR 15 KNOTS AND GUSTY...BUT ARE LIKELY STILL 15
TO 20 KNOTS WELL OFFSHORE OF THE REEF.

.SHORT TERM...TONIGHT THROUGH MONDAY NIGHT...GIVEN THE COMBINATION
OF A DEEP AND WARM MIDDLE AND UPPER LEVEL ANTICYCLONE REMAINING IN
CLOSE PROXIMITY TO THE FLORIDA KEYS...WITH THE POSITION OF A SURFACE
LOW LEVEL RIDGE ACROSS THE FLORIDA PENINSULA...EXPECT TO CONTINUE
WITH CHAMBER OF COMMERCE WEATHER ACROSS THE FLORIDA KEYS...WITH
TEMPERATURES REACHING THE LOWER 80S THROUGH THE PERIOD...AND
OVERNIGHT LOWS ONLY FALLING INTO THE LOWER TO MIDDLE 70S. THIS
PATTERN IS MORE SYMPTOMATIC OF EARLY FALL THAN LATE FALL...AS STRONG
TROUGHING REMAINS NORTHWEST OF SOUTH FLORIDA AND THE KEYS...WITH
RIDGING TO THE IMMEDIATE NORTH OF THE KEYS...AND WEAKER LOWER
PRESSURE ACROSS THE CARIBBEAN SEA. THIS WILL MAINTAIN MODERATE TO
FRESH EAST TO EAST SOUTHEAST BREEZES ACROSS THE ISLANDS WITH ONLY
SLIGHT CHANCES FOR SHOWERS...MAINLY VERY LATE AT NIGHT/EARLY
MORNING...AS THERE WILL BE AMPLE MOISTURE FROM THE SURFACE TO ABOUT
850 MB...WITH DRIER AIR ALWAYS MIXING OUT SHOWER ACTIVITY BY LATE
MORNING/EARLY AFTERNOON...GIVEN THE INSOLATION FROM A LOWER SUN
ANGLE AT THIS TIME OF YEAR. SO THIS WILL JUSTIFY DIME POPS IN THE
GRIDS THRU THE PERIOD.

.EXTENDED...TUESDAY THRU FRIDAY...THE DEEPEST MID-LEVEL RIDGING
WILL GRADUALLY SLIDE MUCH FARTHER SOUTHEASTWARD AWAY FROM SOUTH
FLORIDA AND THE KEYS...WITH SLIGHTLY LOWER (500 MB) MID LEVEL
HEIGHTS EXPECTED ACROSS THE KEYS BY TUESDAY AND TUESDAY NIGHT...AND
THE MEAN AXIS OF THE DEEPER LONGWAVE TROUGHING OVER THE CONUS WILL
SLIDE TOWARDS THE EASTERN SEABOARD. THIS WILL ALLOW FOR THE SURFACE
CENTER OF A 1035-1040 MB PLUS ARCTIC ANTICYCLONE TO REACH THE OHIO
VALLEY TUESDAY NIGHT AND REMAIN THERE THROUGH ABOUT WEDNESDAY
NIGHT...BEFORE SLIDING TO THE MID ATLANTIC STATES THURSDAY AND
FRIDAY. SO WE WOULD EXPECT FRESHENING BREEZES WITH HIGH AND LOW
TEMPERATURES TO DROPPING PERHAPS 2 TO 4 DEGREES. ALSO GIVEN THE
STRONG LOWER LEVEL CONVERGENCE...EXPECT SLIGHTLY BETTER COVERAGES OF
LATE NIGHT/EARLY MORNING SHOWERS...(GIVEN A MOISTENING SURFACE TO
700 MB)...SO WILL MAINTAIN 20% FOR SHOWERS FOR DAY 6 AND 7...WITH NO
CLEAR SIGNS OF FROPA AS OF YET IN THE LATEST MODEL DATA THRU DAY 7.

&&

.MARINE...SMALL CRAFT WILL LIKELY NEED TO EXERCISE CAUTION ACROSS
HAWK CHANNEL AND THE ATLANTIC WATERS OUT 60 NM FROM THE FLORIDA REEF
TONIGHT THROUGH SATURDAY NIGHT...AND ACROSS ALL WATERS IN THE MARINE
DISTRICT SUNDAY THROUGH MONDAY. CAUTIONARY HEADLINES WILL CONTINUE
IN PLACE ACROSS HAWK CHANNEL AND THE ATLANTIC WATERS OUT 60 NM FROM
THE FLORIDA REEF AGAIN MONDAY NIGHT AND TUESDAY. THERE IS STILL A
GOOD POSSIBILITY THAT A SMALL CRAFT ADVISORY MAY BE REQUIRED ACROSS
THE FLORIDA STRAITS THROUGHOUT THIS PERIOD...BUT CONFIDENCE IS TOO
LOW TO ADVERTISE BASED ON PRESENT MODEL GUIDANCE...BUT ADVISORIES
MAY BE POSTED AT ANY TIME THRU THIS PERIOD.

THEREAFTER...WINDS AND SEAS MAY LET DOWN BELOW HEADLINE OR ADVISORY
CRITERIA BRIEFLY DURING TUESDAY NIGHT...BEFORE FRESH NORTHEAST
BREEZES RETURN AGAIN WEDNESDAY AND WEDNESDAY NIGHT...WITH SMALL
CRAFT ADVISORIES LOOKING MORE LIKELY ACROSS HAWK CHANNEL AND THE
FLORIDA STRAITS...AND CAUTIONARY HEADLINES REMAINING IN PLACE
ACROSS THE REST OF THE WATERS IN THE MARINE DISTRICT.

&&

.AVIATION...
VFR CONDITIONS WILL PREVAIL AT EYW AND MTH THIS AFTERNOON AND
TONIGHT. BRIEF...MVFR CONDITIONS ARE CONCEIVABLE AT EYW AND MTH
SATURDAY MORNING. THIS POSSIBILITY IS NOT GREAT ENOUGH TO PLACE IN
THE TERMINAL FORECASTS AT THIS TIME. SUSTAINED EAST TO SOUTHEAST
WINDS NEAR 20 KNOTS FROM JUST OFF THE SURFACE TO ABOUT 5000 FEET
WILL DECREASE TO NEAR 15 KNOTS THIS EVENING.

&&

.CLIMATE...
ON THIS DATE IN KEYS WEATHER HISTORY...IN 1876...THE HIGH
TEMPERATURE IN KEY WEST WAS ONLY 61 DEGREES. THIS SET THE DAILY
RECORD FOR COOLEST MAXIMUM TEMPERATURE MEASURED IN KEY WEST ON
DECEMBER 6TH...A RECORD WHICH STILL STANDS 137 YEARS LATER.
TEMPERATURE RECORDS AT KEY WEST DATE BACK TO 1872.

&&
.PRELIMINARY POINT TEMPS/POPS...
KEY WEST  73  83  73  84  75 / 10  10  10  10  10
MARATHON  73  84  73  83  75 / 10  10  10  10  10
&&

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

$$

PUBLIC/MARINE/GRIDS..........FUTTERMAN
AVIATION/NOWCASTS/CLIMATE....BS
UPPER AIR/DATA ACQUISITION...PARKE

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