237
FXUS62 KKEY 040255
AFDKEY

AREA FORECAST DISCUSSION FOR THE FLORIDA KEYS
NATIONAL WEATHER SERVICE KEY WEST FL
955 PM EST SUN MAR 3 2013

.DISCUSSION...
.CURRENTLY...NIGHTTIME SATELLITE VIEWS SHOW LITTLE CHANGE IN LOCALIZED
CLOUD COVER FROM THE AFTERNOON TIME PERIOD WHEN VISIBLE SATELLITE
IMAGERY SHOWED MOSTLY CLOUDY CONDITIONS DUE TO WIDESPREAD CUMULUS
DEVELOPMENT. KBYX RADAR SHOWS A MOSTLY CLEAR SCAN...SAVE A FEW LIGHT
SPRINKLES THAT ARE MIGRATING TO THE SOUTH ACROSS THE FLORIDA
STRAITS. WINDS HAVE BEEN OSCILLATING THROUGH THE COURSE OF THE LATE
AFTERNOON AND EVENING WITH THE RHYTHM OF PASSING OPEN CELL CUMULUS
FEATURES...AND HAVE RECENTLY SURGED TO NEAR 20 KNOTS AT THE AREA
CMAN STATIONS. TEMPERATURES ARE HOVERING AROUND 60 DEGREES ALONG THE
ISLAND CHAIN...THOUGH A FEW AREAS ARE ALREADY SEEING THE UPPER 50S IN
THE UPPER KEYS WHERE WINDS HAVE SLACKENED A BIT OVER LAND. EVENING
SOUNDING CAME IN WITH A SIGNIFICANTLY DRY PROFILE ABOVE 850 MB...AND
A PWAT VALUE FOR THE COLUMN OF ONLY 0.54 INCHES (53 PERCENT OF OUR
NORMAL VALUE).

.SHORT TERM...NIGHTTIME FORECASTS SEEM WELL ON TRACK FOR THE PUBLIC
ZONES. THE ONLY UPDATE THIS EVENING WILL BE TO REMOVE TRANSITIONAL
WORDING OF SHOWERS...AS THERE IS LITTLE INDICATION THAT SHOWERS
SHOULD REDEVELOP DUE TO A SUBSTANTIALLY CAPPED AND DRY PROFILE...IN
THE NOCTURNAL ENVIRONMENT. ONLY SIGNIFICANT QUESTION MARK IN THE
FORECAST IS IN THE LOW TEMPERATURES FOR TONIGHT. WILL MAINTAIN THE
SPLIT ZONES ON ACCOUNT OF THE TEMP GRADIENT BETWEEN THE MIDDLE AND
UPPER KEYS...DUE TO COOLER CONTINENTAL DRAINAGE OFF THE MAINLAND.
DIPS INTO THE NEAR 50 OR MID 50S RANGE WILL STILL TAKE SOME DOING
TONIGHT... BUT WITH A FORECASTED DECREASE IN THE WINDS NEAR
DAYBREAK...THINK THAT THESE NUMBERS ARE CERTAINLY PLAUSIBLE. IF WINDS
GROSSLY DECOUPLE...WHICH IS POSSIBLE...EVEN LOWER NUMBERS ARE YET A
POSSIBILITY...MAINLY IN THE UPPER KEYS. NO SIGNIFICANT CHANGES ON
ACCOUNT OF THE UNCERTAINTY.

&&

.MARINE...
UPDATE TO THE MARINE FORECAST LARGELY MAINTAINS THE FABRIC OF THE
PREVIOUS FORECAST WITH THE EXCEPTION OF A SMALL CRAFT ADVISORY BEING
HOISTED FOR FLORIDA BAY. THE WINDS AT THE NORTH FLORIDA BAY AND
LONG KEY STATIONS RECENTLY INCREASED TO NEAR 20 KNOTS AND
GUSTY...AND MOLASSES REEF LIGHT IS FORECASTED TO TREND UPWARDS
THROUGH THE OVERNIGHT HOURS TONIGHT. AS WAS MENTIONED BEFORE...WINDS
HAVE BEEN GUSTY IN THE VICINITY OF OPEN-CELL CUMULUS BANDS... WHICH
MAY HAVE INTRODUCED SLIGHTLY HIGHER LOCALIZED SEAS ACROSS THE
REGION... BUT SIGNIFICANT CHANGES IN THE PREVAILING SEA HEIGHT SHOULD
BE MINIMAL WITH THE SHORT DURATION OF THESE WINDS. NONE THE LESS...
WILL KEEP SEA HEIGHTS SOLIDLY WITHIN THE SMALL CRAFT CRITERIA RANGE
OVER THE DEEP WATERS OF THE GULF AND FLORIDA STRAITS. VERY FEW
CHANGES BEYOND THE SHORT TERM FORECASTS...AS GRIDS AND TEXT FORECASTS
SEEM WELL ON TRACK WITH THE LATEST MODEL RUNS.

&&

.AVIATION...
VFR CEILINGS ARE EXPECTED FOR A SHORT WHILE LONGER IN THE
KEYS...ESPECIALLY AT KEYW. OVERALL CLOUD COVERAGE WILL DIMINISH
THROUGH THE OVERNIGHT PERIOD AT BOTH KEYW AND KMTH. SURFACE BREEZES
WILL AVERAGE NEAR 320 DEGREES BETWEEN 10 AND 15 KNOTS THROUGH MUCH
OF THE OVERNIGHT PERIOD...THEN MODERATE WHILE TURNING MORE TO THE
NORTH/NORTHEAST MONDAY MORNING.

&&

.CLIMATE...
ON THIS DATE IN KEYS WEATHER HISTORY...IN 1986...THE LOW TEMPERATURE
AT KEY WEST INTERNATIONAL AIRPORT WAS 47 DEGREES. THIS SET THE DAILY
RECORD FOR MINIMUM TEMPERATURE MEASURED IN KEY WEST ON MARCH 3RD.
IN ADDITION...THIS LOW TEMPERATURE OF 47 DEGREES IS THE MINIMUM
TEMPERATURE EVER MEASURED IN KEY WEST DURING THE MONTH OF MARCH.
TEMPERATURE RECORDS AT KEY WEST DATE BACK TO 1872.

&&

.KEY WATCHES/WARNINGS/ADVISORIES...
FL...NONE.
GM...SMALL CRAFT ADVISORY UNTIL 5 AM EST MONDAY FOR GMZ032>034-042>044-
     052>055-072>075.

&&

$$

PUBLIC/MARINE.........MSB
AVIATION/NOWCASTS.....04

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