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386
FXUS62 KKEY 240321
AFDKEY

AREA FORECAST DISCUSSION FOR THE FLORIDA KEYS
NATIONAL WEATHER SERVICE KEY WEST FL
1021 PM EST SUN NOV 23 2014

.DISCUSSION...
.CURRENTLY...
SKIES ARE PARTLY CLOUDY WITH MAINLY PASSING ALTO CUMULUS AND CIRRUS
DECKS ABOVE 5000 FEET. RADAR RETURNS HAVE BEEN FEW AND FAR BETWEEN
TONIGHT...BUT HAVE BEEN MOST APPARENT IN THE FORM OF LOW TOPPED
RAPIDLY MOVING SHOWERS MAINLY ACROSS THE NEARSHORE WATERS WHERE LOW
LEVEL CONVERGENCE IS MAXIMIZED DUE TO CLASHING WIND REGIMES. MOST
SHOWERS WERE OF DUBIOUS INTENSITY HOWEVER...AND QUESTIONS REMAIN AS
TO HOW MUCH RAINFALL IS ACTUALLY REACHING THE GROUND IN THESE
SHOWERS. WINDS SLACKENED VERY QUICKLY ACROSS THE KEYS DURING THE
LATE AFTERNOON...AND WITH A FEW EXCEPTIONS...EAST- SOUTHEASTERLY
MARINE WINDS ARE 10 TO 15 KNOTS ACROSS THE STRAITS OF FLORIDA...AND
NEAR 10 KNOTS OR LESS ACROSS THE GULF AND BAYSIDE WATERS. THE EVENING
SOUNDING CAME IN WITH A RAPID REDUCTION IN MID AND UPPER LEVEL
MOISTURE VALUES...AND AN OVERALL DECREASE IN PWAT TO 1.59 INCHES.
LOW LEVEL WINDS SHOWED SIGNIFICANT VEERING...BUT NOT AS MUCH AS MUCH
SPEED SHEER AS WAS INDICATED BY PREVIOUS MODEL OUTPUT SOUNDINGS. LOW
LEVEL MOISTURE REMAINS HIGH...AND INSTABILITY BELOW 850 MB WAS
SURPRISINGLY HIGH. THE LOWEST CAPPING INVERSION IS BASED AT THAT
LEVEL HOWEVER...AND WILL REPRESENT A SIGNIFICANT IMPEDANCE TO
VERTICAL DEVELOPMENT OVERNIGHT.

.SHORT TERM...
SLIGHT MODIFICATIONS WERE REQUIRED FOR THE FIRST PERIOD OF THE PUBLIC
FORECAST THIS EVENING. SKIES WILL REMAIN PARTLY CLOUDY OVERNIGHT WITH
A MID AND UPPER LEVEL PLUME OF MOISTURE STREAMING TOWARDS THE
NORTHEAST ACROSS SOUTH FLORIDA AND THE FLORIDA KEYS. THE VEERING
PROFILE...SIGNIFICANT AMOUNTS OF MOISTURE AND MODEST INSTABILITY ALL
IN THE LOW LEVELS WILL CONTINUE TO COMPETE AGAINST THE SIGNIFICANT LOW
LEVEL CAPPING INVERSION AND AS SUCH FEEL CONFIDENT THAT SHOWERS
SHOULD REMAIN IN THE VERY SLIGHT CATEGORY OVERNIGHT AND EXPLICIT
MENTION OF THESE SHOWERS IN THE ZFP ARE NOT WARRANTED. WINDS ALONG
THE ISLAND CHAIN SHOULD REMAIN GENERALLY LIGHT 5 TO 10 MPH.
TEMPERATURES WILL STRUGGLE TO COMPLETELY DIP INTO THE MID 70S
OVERNIGHT ON ACCOUNT OF RICH DEW POINTS ACROSS THE ISLANDS...BUT A
FEW BREAKS IN THE CLOUDS THAT ARE FORECASTED NEAR DAYBREAK SHOULD
ALLOW AT LEAST SOME MEASURE OF RADIATIONAL COOLING AND EROSION OF
SURFACE DEW POINTS. SEE NO REASON TO CHANGE OVERNIGHT LOW TEMPERATURE
OR ANY OTHER GRIDDED OR TEXT FORECASTS AT THIS TIME.

ONLY OTHER FIRST PERIOD CONCERN IS FOR COASTAL FLOODING AROUND THE
FLORIDA KEYS. NEAR-MAXIMUM LUNAR TIDES AND A GENEROUS RESIDUAL VALUE
OF MAINLY ATMOSPHERIC TIDES WERE OBSERVED TONIGHT AT THE KEY WEST
TIDAL OBSERVING STATION. THESE TWO FACTORS WILL COMBINE TO CREATE
SOME MINOR AMOUNTS OF COASTAL TIDAL FLOODING ACROSS THE KEYS.

&&

.MARINE...
A LATE AFTERNOON UPDATE WAS REQUIRED TO ADJUST FOR RAPIDLY DECREASING
WINDS ACROSS THE KEYS. AFTER THIS UPDATE...A FEW CHANNELS OF HIGHER
WINDS HAVE BEEN OBSERVED ACROSS THE HAWK CHANNEL ZONES... BUT IN
AGGREGATE...EAST -SOUTHEAST WINDS NEAR 15 KNOTS HAVE BEEN OBSERVED
ACROSS THE STRAITS OF FLORIDA. EXPECT LIGHT TO MODERATE WINDS TO
PREVAIL FOR THE NEXT TWO DAYS AND NIGHTS AT THIS TIME BEFORE ANOTHER
FRONT BEGINS TO APPROACH THE ISLANDS FROM THE NORTH AND WEST EARLY ON
WEDNESDAY.

&&

.AVIATION...
EXPECT VFR CONDITIONS AT THE KEY WEST AND MARATHON TERMINALS
OVERNIGHT AND MONDAY. A GENTLE TO MODERATE SOUTHEAST BREEZE TONIGHT
WILL TURN MORE TO THE SOUTH ON MONDAY.

&&

.CLIMATE...
ON THIS DATE IN KEYS WEATHER HISTORY...IN 1944...THE LOW TEMPERATURE
IN KEY WEST DIPPED TO 58 DEGREES. THIS SET THE DAILY LOW TEMPERATURE
RECORD FOR NOVEMBER 23 IN KEY WEST. TEMPERATURE RECORDS FOR KEY WEST
DATE BACK TO 1872.


&&

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

$$

PUBLIC/MARINE.........MSB
AVIATION/NOWCASTS.....04
DATA COLLECTION.......FLING

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