FXUS62 KEYW 020910
AFDEYW

FLORIDA KEYS AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE KEY WEST FL
409 AM EST WED APR 2 2003

.OBSERVATIONS/TRENDS...
AIR TEMPERATURES AT BOTH ISLAND AND REEF SITES HAVE BEEN HOLDING 
STEADY IN THE UPPER 60S. DEWPOINTS HAVE CREPT INTO THE MID 50S. 
MODERATE TO FRESH NORTHEAST TO EAST BREEZES CONTINUE ACROSS THE 
COASTAL WATERS THIS MORNING...WITH GUSTS STILL OVER 20KT MOST 
PLACES. KBYX WSR-88D CLEAR-AIR BASE REFLECTIVITY LOOPS OVER THE PAST 
SEVERAL HOURS CLEARLY DELINEATE THE ZONE BETWEEN THE MORE DISTURBED 
SEA SURFACE INTERFACE JUST BEYOND THE REEF AND THE RELATIVELY CALMER 
WATERS INSIDE THE REEF. DIDO FOR THE GULF FLATS/OPEN GULF INTERFACE 
TRANSITION ZONE NORTH OF THE LOWER KEYS. THE RADAR ALSO DETECTS A 
FEW SPRINKLES FALLING OUT OF THE THICK MARINE STRATOCUMULUS WITHIN 
DEEPENING EASTERLY FLOW.

AN UPPER-LEVEL COMPOSITE ANALYSIS REVEALS A DEEP-LAYERED RIDGE 
EXTENDING FROM THE WESTERN CARIBBEAN NORTH OVER THE GULF OF MEXICO 
AND CENTRAL U.S. THE RIDGE IS SUPPORTING A SPRAWLING LOWER- 
TROPOSPHERIC ANTICYCLONE CENTERED THIS MORNING ACROSS THE NORTHEAST 
GULF OF MEXICO. THE ANTICYCLONE COMPRISES A RAPIDLY-MODIFYING 
CONTINENTAL POLAR AIR MASS. THE FLORIDA KEYS LAY WELL SOUTH OF THE 
MAIN EAST-WEST RIDGE AXIS...HENCE THE CONTINUED BREEZY 
CONDITIONS.    

.SHORT-RANGE FORECASTS...TODAY THROUGH THURSDAY NIGHT...
THIS PERIOD WILL BE CHARACTERIZED BY RAPID AIR MASS MODIFICATION AS 
MODERATE TO FRESH EASTERLY BREEZES CONTINUE TO ASSIST IN THE 
TRANSPORT OF SENSIBLE HEAT AND WATER VAPOR FROM OCEANIC BOUNDARY 
LAYER TO ATMOSPHERIC BOUNDARY LAYER. AIR TEMPERATURES SHOULD CLIMB 
INTO THE UPPER 70S TODAY...AND NEAR 80F ON THURSDAY...WITH LOWS NEAR 
70F TONIGHT...AND IN THE LOWER 70S THURSDAY NIGHT. TRENDS IN 
INFRARED SATELLITE IMAGERY SUGGEST MOSTLY CLOUDY CONDITIONS FOR AT 
LEAST THE FIRST HALF OF THE DAY THANKS TO THE THICK STRATOCUMULUS 
CURRENTLY NOTED ACROSS THE ENTIRE REGION BETWEEN THE KEYS AND THE 
BAHAMAS. ON THURSDAY...NUMERICAL MODELS SUGGEST A PERIOD OF THICK 
CIRRUS ASSOCIATED WITH AN EASTWARD-MOVING SOUTHERN STREAM UPPER- 
TROPOSPHERIC SHORT WAVE TROUGH. 

.MEDIUM-RANGE FORECASTS...FRIDAY THROUGH TUESDAY...
THE LARGE WESTERN ATLANTIC ANTICYCLONE WILL CONTINUE TO SLOWLY 
WEAKEN...AND WIND SPEEDS SHOULD GRADUALLY COME DOWN. ISOLATED 
SHOWERS WILL BE MAINTAINED AS THE BOUNDARY LAYER CONTINUES TO 
MOISTEN IN EASTERLY FLOW. BY SATURDAY OR SUNDAY...THE ONCE-CHILLY CP 
AIR MASS WILL HAVE ALMOST COMPLETELY MODIFIED...AND DEWPOINTS WILL 
ONCE AGAIN BE ABOVE 70F...WITH AIR TEMPERATURES SLIGHTLY ABOVE 
NORMAL.

.PRELIMINARY POINT FORECAST NUMBERS FOR FIVE PERIODS...
KEY WEST  77/71/81/72/83  0/0/10/10/10
MARATHON  79/72/83/73/85  0/0/10/10/10

.EYW...SCA ATLANTIC WATERS.

K. KASPER