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622
FXUS62 KKEY 211755
AFDKEY

AREA FORECAST DISCUSSION FOR THE FLORIDA KEYS
NATIONAL WEATHER SERVICE KEY WEST FL
155 PM EDT SUN SEP 21 2014

.DISCUSSION...
.CURRENTLY...
FROM VISIBLE SATELLITE INTERROGATION WE FIND A DECAYING TROUGH ACROSS
SOUTH FLORIDA AND THE KEYS. AN UPPER LOW OVER THE MID ATLANTIC COAST
IS BEING EJECTED TO THE NORTHEAST AHEAD OF A LONG WAVE TROUGH DIPPING
THROUGH THE GREAT LAKES AND OHIO RIVER VALLEY. THE KBYX RADAR IS
SHOWING SOME RETURNS OF STRATOFORM AND VERY LIGHT RAIN OR SPRINKLES
ALONG THE TROUGH. WINDS MAINLY SOUTH AROUND 5 KNOTS ACROSS THE ISLAND
CHAIN AND SURROUNDING WATERS.

.FORECAST...
AS MENTIONED ABOVE THE MID ATLANTIC UPPER LOW LIFTS OUT AND THE LARGE
TROUGH MOVES EAST OF THE GREAT LAKES MOVES TO THE EAST. THE
SUBTROPICAL RIDGE WILL TAKE DOMINANCE OF THE KEYS AREA THROUGH
MONDAY. AS THE LARGE SCALE TROUGH HEADS OFF TO THE EAST AN IMMENSE
ROBUST RIDGE WILL MOVE OVER THE EASTERN UNITED STATES. THE KEYS WILL
BE IN THE SOUTHERN PERIPHERY OF THIS ROBUST RIDGE WHICH WILL INCREASE
WINDS OUT OF THE EAST. ADDITIONALLY...A WEAK TROPICAL WAVE WILL SLIDE
ACROSS THE CARIBBEAN FEEDING MOISTURE INTO THE ENVIRONMENT...AND
INCREASING THE PRESSURE GRADIENT OVER THE AREA. LATE MONDAY NIGHT
THROUGH TUESDAY NIGHT HAVE HIGH END CHANCE OF SHOWERS AND
THUNDERSTORMS FOR THE ISLAND CHAIN...AND NUMEROUS SHOWERS AND
SCATTERED THUNDERSTORMS OVER THE COASTAL WATERS. ALSO WITH THE FOCUS
OF THE GRADIENT AROUND THE RIDGE AND WITH THE WAVE PASSING TO THE
SOUTH WILL LIKELY HAVE TO ADOPT A CAUTIONARY STATEMENT FOR TUESDAY
THROUGH WEDNESDAY FOR AT LEAST A PORTION OF THE KEYS WATERS. THE
RIDGE WILL BREAK DOWN ON THURSDAY RELAXING WINDS WHILE THE
SUBTROPICAL RIDGE NOSES BACK ACROSS SOUTH FLORIDA AND THE KEYS.
DURING THIS TIME WITH AND THROUGH SATURDAY WILL GRADUALLY DROP BACK
INTO A MORE SEASONAL WEATHER PATTERN WITH LOW END CHANCE POPS.

&&

.MARINE...
THE SUBTROPICAL RIDGE WILL GRADUALLY BUILD OVER THE KEYS AREA AND THE
FLORIDA PENINSULA THROUGH MONDAY NIGHT. A ROBUST RIDGE WILL BUILD
OVER THE SOUTHEASTERN STATES AND COMBINE WITH A WESTWARD MOVING WAVE
CROSSING CUBA AND THE CARIBBEAN TUESDAY...RESULTING IN A WIND SURGE
AND SCATTERED SHOWERS AND THUNDERSTORMS. A CAUTIONARY STATEMENT MAY
BE REQUIRED TUESDAY NIGHT AND EARLY WEDNESDAY.

&&

.AVIATION...
VFR CONDITIONS ARE EXPECTED AT THE KEY WEST AND MARATHON TERMINALS
THROUGH THE OVERNIGHT PERIOD. POCKETS OF LIGHT RAIN OR ISOLATED TO
SCATTERED SHOWERS SHOULD FAVOR THE AREAS NORTH OF THE ISLAND CHAIN
LATER THIS AFTERNOON INTO EARLY EVENING. THE LATEST TAFS DID NOT
ADVERTISE SUB-VFR CONDITIONS FOR THE ENTIRE FORECAST PERIOD...WITH
LIGHT AND VARIABLE WINDS EXPECTED.

&&

.CLIMATE...
ON THIS DATE IN KEYS WEATHER HISTORY...1948...A HURRICANE INTENSIFIED
AS IT MOVED NORTH NORTHEAST OFF WESTERN CUBA CROSSING OVER BOCA CHICA
AS A CATEGORY THREE HURRICANE. THE SUSTAINED WIND AT BOCA CHICA WAS
MEASURED AT 122 MPH...WITH A PEAK WIND OF 140 MPH BEFORE THE
ANEMOMETER BLEW AWAY. IN KEY WEST THE MINIMUM PRESSURE WAS 28.45
INCHES OF MERCURY...963 MB...A PEAK WIND OF 84 MPH...WITH A 5 TO 6
FOOT STORM SURGE ABOVE MEAN SEA LEVEL. THE RADIUS OF THE EYE OF THE
STORM WAS ONLY 10 MILES. KEY WEST MEASURED 4.53 INCHES OF RAINFALL
WHICH SET THE DAILY RECORD RAINFALL IN KEY WEST ON SEPTEMBER 21ST.

&&

.PRELIMINARY POINT TEMPS/POPS...
KEY WEST  79  88  79  87 / 40 30 50 50
MARATHON  80  87  79  86 / 40 30 50 50

&&

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

$$

PUBLIC/MARINE.........BWC
AVIATION/NOWCASTS.....11
DATA COLLECTION.......FLING

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