Area Forecast Discussion
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000
FXUS62 KKEY 031402
AFDKEY

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE KEY WEST FL
1000 AM EDT SUN MAY 3 2015

.DISCUSSION...IN THE MID AND UPPER LEVELS...(700-200 MB)...LATEST
AVAILABLE IR IMAGERY AS OF 900 AM OVERLAID WITH MODEL STREAMLINE
ANALYSIS CONTINUES TO DEPICT MAINLY ZONAL MID AND UPPER FLOW ACROSS
THE WESTERN AND CENTRAL CONUS WITH BROADLY CYCLONIC FLOW ACROSS THE
EASTERN UNITED STATES AS WELL AS THE GULF OF
MEXICO...BAHAMAS...EXTENDING INTO THE NORTHWESTERN CARIBBEAN SEA.
THE SOUTHERN BRANCH OF THE JET CONTAINS THE HIGHEST MAGNITUDE OF MID
AND UPPER WINDS...WITH 75 TO 100 KNOTS AT 250 MB MIGRATING FROM
MEXICO AND CENTRAL AMERICA BUT DECELERATING TO NEAR 50 KNOTS ACROSS
CUBA...SOUTH FLORIDA AND THE KEYS. AT 500 MB....A SIMILAR
DECELERATION IS OBSERVED SYMPTOMATIC IN THE DEVELOPMENT OF A MIDDLE
LEVEL TROUGH/LOW PRESSURE SYSTEM OVER THE CENTRAL GULF.

AT THE SURFACE AND IN THE LOWER TO MIDDLE LEVELS...SURFACE TO 700
MB...AS OF 900 AM...THE CENTER OF A 1022-1025 YET STRENGTHENING
SURFACE ANTICYCLONE IS POSITIONED JUST EAST OF SAVANNAH...BUT A WEAK
SURFACE TROUGH EXISTS TO THE WEST OF THE KEYS WITH ADDITIONAL
SURFACE/LOWER LEVEL TROUGHINESS SOUTH OF CENTRAL CUBA. AS A
RESULT...THE 12Z SOUNDING ILLUSTRATED A FAIRLY DRY LOWER TO MID
TROPOSPHERE...WITH FRESH TO STRONG NORTHEAST TO EASTERLIES FROM OFF
THE SURFACE TO 850 MB AND COLUMNAR PWAT AT 1.14 INCHES...WITH DRY
AIR AND GENTLE YET CHAOTIC WIND DIRECTIONS ABOVE THAT UP TO ABOUT
400 MB.

.CURRENTLY...AS OF 900 AM...TEMPERATURES HAVE RISEN INTO THE MIDDLE
AND UPPER 70S WITH DEWPOINTS IN THE LOWER TO MID 60S ACROSS THE
ISLANDS. RADAR ONLY DETECTS SHOWERS NOW OVER THE GULF WEST OF THE
FLORIDA STRAITS...BUT NO ECHOES IN THE ENTIRE SERVICE AREA ATTM. C-
MAN STATIONS ACROSS THE FLORIDA REEF...AROUND SMITH SHOAL
LIGHT...AND FLORIDA BAY ARE RECORDING WINDS NEAR 20 KNOTS AND GUSTY
EXCEPT 20 TO 25 KNOTS OUT AT PULASKI SHOAL LIGHT.

.SHORT TERM...LARGE SCALE MODELS CAN BE FICKLE IN THEIR
DEPICTION...RESOLUTION...AND DEVELOPMENT OF COLD CORE MIDDLE AND
UPPER LEVEL LOW PRESSURE SYSTEMS UPSTREAM OF THE KEYS AT OUR
LATITUDE. AS SUCH...THE BOUNDARY LEVEL MOISTURE HAS BEEN SLOW TO
ADVECT ACROSS THE KEYS AND SURROUNDING WATERS LAST NIGHT AND
TODAY...NEVERTHELESS...THE COMBINATION OF STRONG SURFACE RIDGING
EAST OF THE SOUTHEASTERN UNITED STATES AND TROUGHING TO THE SOUTH
AND WEST WILL CONTINUE TO MAINTAIN THE FRESH TO STRONG BREEZES
ACROSS THE ISLANDS AND SURROUNDING WATERS FOR THE BALANCE OF TODAY
AND INTO THE EVENING HOURS. HAVE ALREADY PERFORMED AN UPDATE EARLIER
TO REDUCE SHOWER THREAT TO ONLY A SLIGHT CHANCE AND REMOVE
THUNDER...EXCEPT IN THE FLORIDA STRAITS. NO OTHER CHANGES ATTM.

&&

.MARINE...A SMALL CRAFT ADVISORY WILL REMAIN IN PLACE THROUGH TODAY
THROUGH TONIGHT...CONTINUING INTO MONDAY...WITH PORTIONS OF THE
WATERS STILL UNDER AN ADVISORY ON MONDAY NIGHT.

&&

.AVIATION...UNTIL 00Z/4TH...VFR CONDITIONS WILL PREVAIL AT THE KEY
WEST AND MARATHON TERMINALS. MOSTLY EAST WINDS OF 10 TO 15 KNOTS
WITH GUSTS OF 20 TO OCCASIONALLY 25 KNOTS CAN BE EXPECTED AT THE
ISLAND AIRPORTS.

&&

.KEY WATCHES/WARNINGS/ADVISORIES...
FL...NONE.
GM...SMALL CRAFT ADVISORY TODAY AND TONIGHT
FOR GMZ031>035-042>044-052>055-072>075

&&

$$

PUBLIC/MARINE.........FUTTERMAN
AVIATION/NOWCASTS.....APA
DATA COLLECTION.......VICKERY

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