Area Forecast Discussion
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FXUS62 KKEY 271447
AFDKEY

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE KEY WEST FL
945 AM EST FRI FEB 27 2015

.DISCUSSION...IN THE MID AND UPPER LEVELS...(700-200 MB)LATEST
AVAILABLE IR IMAGERY OVERLAID WITH MODEL STREAMLINE ANALYSIS AS OF
900 AM DETAILS A LARGELY CYCLONIC MID AND UPPER FLOW PATTERN IN
PLACE ACROSS THE ENTIRE CONUS...WITH 75 TO 100 KNOT SOUTHWESTERLIES
AT 250 MB RIDING ACROSS FLORIDA AND THE KEYS FROM CENTRAL MEXICO.
THERE ARE SOME MIDDLE LEVEL IMPULSES...WEAK PVA AT 500 MB...WITHIN
THE CYCLONIC FLOW ACROSS THE SOUTHEASTERN GULF OF MEXICO.

AT THE SURFACE AND IN THE LOWER TO MIDDLE LEVELS...SURFACE TO 700
MB...LATEST IR IMAGERY OVERLAID WITH AVAILABLE MARINE AND LAND
SURFACE OBSERVATIONS AND ANALYSIS DETAIL A 1040 MB CENTER OF A LATE
WINTER ARCTIC AIRMASS CENTERED OVER NORTHERN MISSOURI. LOCALLY...A
SURFACE FRONT HAS COME TO A HALT IN THE FLORIDA STRAITS SOUTHEAST OF
THE KEYS. THE 12Z MORNING SOUNDING INDICATED THE LOWER TO MID
TROPOSPHERE WAS SOMEWHAT MOIST WITH PWAT AT 1.37 INCHES AND THE
SURFACE FRONT IS VERY SHALLOW OVER THE KEYS WITH GENTLE TO MODERATE
NORTH TO NORTHWESTERLIES FROM THE SURFACE TO TO ONLY ABOUT 975
MB...WITH WINDS BECOMING SOUTH TO SOUTHWEST AND FRESHENING FROM 2500
FEET TO 600 MB.

.CURRENTLY...SKIES HAVE BECOME MOSTLY CLOUDY ACROSS ALL OF THE
ISLANDS THROUGH THE MID MORNING HOURS ACROSS THE ISLANDS AND
ADJOINING WATERS WITH THE LEADING EDGE OF THE WESTWARD MOVING
CLOUDINESS NOW MOVING INTO THE UPPER KEYS...EXCEPT SKIES ARE STILL
MOSTLY SUNNY ACROSS THE OFFSHORE CENTRAL AND EASTERN FLORIDA STRAITS
OFF OF THE UPPER AND MIDDLE KEYS. KEY WEST RADAR DETECTS SOME LIGHT
RAIN ACROSS THE OUTERMOST OFFSHORE GULF WATERS AND AROUND TORTUGAS
NATIONAL PARK. TEMPERATURES ACROSS THE ISLANDS ARE AROUND 70 DEGREES
WITH DEWPOINTS IN THE MID TO UPPER 60S.

.FORECASTS...FOR TONIGHT AND THIS EVENING...THE CENTER OF 1040 MB
ARCTIC HIGH PRESSURE OVER THE CENTRAL PLAINS WILL BEGIN TO BLEED
EASTWARD TOWARDS THE OHIO VALLEY BY DAYS END. LOCALLY THE SURFACE
FRONTAL BOUNDARY WILL REMAIN JUST TO THE SOUTHEAST OF THE
KEYS...CLOSEST TO THE UPPER KEYS. THIS WILL ALLOW FOR STRONGER
SURFACE WINDS ACROSS THE WATERS WEST OF THE SEVEN MILE BRIDGE OUT
BEYOND THE TORTUGAS...BUT THE UPPER AND MIDDLE KEYS ARE CLOSER TO
THE SURFACE FRONT...SO WINDS WILL TAKE TIME TO INCREASE ACROSS THE
FLORIDA BAY AND THE ATLANTIC WATERS OFF OF THE UPPER KEYS. THIS IS
ALREADY INDICATED IN THE GRIDS. ALSO BOTH LATEST AVAILABLE FORECAST
SOUNDINGS FOR THE ECMWF AND THE GFS CONTINUE TO INDICATE MOISTENING
IN THE SURFACE TO 500 MB OVER THE KEYS THRU THE DAY IN AN ANAFRONTAL
ENVIRONMENT ALONG THE KEYS. THEREFORE WILL CONTINUE TO HOLD ONTO A
LOWER CHANCE FOR LIGHT RAIN THROUGHOUT THE REST OF THE DAY ACROSS
THE KEYS.

&&

.MARINE...THIS AFTERNOON AND THIS EVENING...SMALL CRAFT SHOULD
EXERCISE CAUTION FOR THE EXTREME SOUTHEASTERN GULF OF
MEXICO...INCLUDING DRY TORTUGAS AND REBECCA SHOAL CHANNEL...HAWK
CHANNEL FROM THE WEST END OF THE SEVEN MILE BRIDGE THROUGH HALFMOON
SHOAL...AND THE LOWER STRAITS OF FLORIDA SOUTH OF THE DRY TORTUGAS.
A STATIONARY FRONT WILL REMAIN JUST SOUTHEAST OF THE FLORIDA KEYS
TODAY. SMALL CRAFT WILL LIKELY NEED TO EXERCISE CAUTION ACROSS ALL
WATERS THIS EVENING AS THE SURFACE HIGH BUILDS ACROSS THE ENTIRE
MARINE DISTRICT...AS A STRONG HIGH PRESSURE SYSTEM BUILDS NORTHWEST
TO NORTH OF THE FLORIDA KEYS TONIGHT

&&

.AVIATION...
MVFR CONDITIONS WITH BRIEF IFR CONDITIONS ARE POSSIBLE AT THE KEY
WEST AND MARATHON TERMINALS THROUGH LATE MORNING. VFR CEILINGS ARE
EXPECTED TO PERSIST THROUGH THE BULK OF THE AFTERNOON AT BOTH
LOCATIONS. NORTH TO NORTHEAST WINDS WILL BE AT OR AROUND 10 KNOTS AT
MARATHON...AND 10 TO 15 KNOTS AT KEY WEST WITH BRIEFLY HIGHER GUSTS.

&&

.CLIMATE... ON THIS DATE IN KEYS WEATHER HISTORY...IN 1878...2.90
INCHES OF RAIN WAS RECORDED IN KEY WEST. THIS IS A LONG-STANDING
RAINFALL RECORD FOR FEBRUARY 27 IN KEY WEST. RAINFALL RECORDS FOR
KEY WEST DATE BACK TO 1871.

&&

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

$$

PUBLIC/MARINE/GRIDS............FUTTERMAN
AVIATION/NOWCASTS/CLIMATE......04
DATA ACQUISITION/UPPER AIR.....CHESSER


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