Area Forecast Discussion
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000
FXUS62 KKEY 230844
AFDKEY

AREA FORECAST DISCUSSION FOR THE FLORIDA KEYS
NATIONAL WEATHER SERVICE KEY WEST FL
444 AM EDT TUE SEP 23 2014

.DISCUSSION...
GEOSTATIONARY SATELLITE INFRARED CHANNEL AND DOPPLER RADAR ANIMATIONS
HAVE REVEALED WIDESPREAD CLOUDINESS...NUMEROUS SHOWERS...AND
SCATTERED THUNDERSTORMS AROUND THE FLORIDA KEYS AND ADJACENT COASTAL
WATERS EARLY THIS MORNING. SEVERAL MULTICELL LINES AND CLUSTERS HAVE
BEEN DEVELOPING...WITH EMBEDDED VIGOROUS CUMULONIMBUS TOWERS
OCCASIONALLY GROWING TO EXCEED 50000 FEET ABOVE GROUND LEVEL.
SATELLITE INFRARED CLOUD TOP TEMPERATURES HAVE DIPPED AS LOW AS -78C
WITH THE MOST INTENSE CONVECTION. PERIODIC GROWTH AND DECAY OF
CONVECTIVE CLUSTERS IN THE VERY MOIST ENVIRONMENT HAS YIELDED VARIOUS
REGIONS OF STRATIFORM RAIN FALLING FROM REMNANT ALTOSTRATUS AND
NIMBOSTRATUS DECKS. THE CONVECTIVE ELEMENTS ARE NOT MOVING FAST AT
ALL...CONSISTENT WITH THE FAIRLY WEAK LAYER MEAN WIND SPEEDS. STORM
MOTIONS HAVE VARIED CONSIDERABLY IN DIRECTION...WITH SPEEDS
GENERALLY LESS THAN 15 KNOTS. DESPITE THE WEAK WIND FIELDS...A DEEP
MOISTURE CONVERGENCE ZONE HAS SET UP ACROSS THE AREA THANKS TO THE
JUXTAPOSITION OF A WEAK FRONTAL TROUGH WITH A WEAK EASTERLY WAVE AND
WIND SURGE. PORTIONS OF THE UPPER AND MIDDLE KEYS RECEIVED RAINFALL
EARLIER. HOWEVER...THE LOWER KEYS HAVE REMAINED DRY OVERNIGHT...AND
REALLY...FOR MUCH OF THE LAST 24 HOURS. THIS PROBABLY IS GOING TO
CHANGE LATER THIS MORNING AS BOTH OUTFLOW BOUNDARIES AND ACTIVE
CONVECTION BEGINS TO CONVERGE ON THE REMAINING FAVORABLE EQUIVALENT
POTENTIAL TEMPERATURE POOL ACROSS THE SERVICE AREA. FOR THE MOMENT...
AIR TEMPERATURES IN THE LOWER KEYS ARE IN THE LOWER 80S...WHILE
TEMPERATURES IN MARATHON ARE RAIN COOLED IN THE UPPER 70S.

FORECASTS -- AT LEAST SOME OF TODAY SHOULD BE CLOUDY...WET...AND
STORMY. WE HAVE INCREASED RAIN CHANCES UP TO 70 PERCENT FOR THE 6AM-
6PM PERIOD. LOCALLY HEAVY RAINFALL IS POSSIBLE DUE TO SLOW CELL
MOVEMENT. CLOUDY SKIES SHOULD PREVAIL AT MOST TIMES IN MOST AREAS.
TONIGHT HAS ABOVE AVERAGE RAIN CHANCES AS WELL. LARGE-SCALE FORCING
FOR ASCENT REMAINS INFLUENTIAL LOCALLY ALBEIT WEAK. BY THURSDAY...A
LARGE ANTICYCLONE WILL BE INTENSIFYING RAPIDLY OVER THE WESTERN NORTH
ATLANTIC BASIN...AND THIS SHOULD KEEP CONDITIONS OCCASIONALLY BREEZY
AND UNSETTLED WEATHERWISE FROM WEDNESDAY THROUGH THURSDAY NIGHT AS
RICH TROPICAL MOISTURE IS WORKED ON BY A CONVERGENT MARITIME TROPICAL
BOUNDARY LAYER. THE ANTICYCLONE WILL WEAKEN GRADUALLY FRIDAY THROUGH
SUNDAY...RESULTING IN MORE CLIMATOLOGICAL VALUES FOR SKY COVER...RAIN
CHANCES...AND TEMPERATURES.
&&

.MARINE...
NO ADVISORIES AND NO HEADLINES. HOWEVER...WINDS AND SEAS WILL BE
HIGHER AND MORE VARIABLE IN AND NEAR NUMEROUS SHOWERS AND SCATTERED
THUNDERSTORMS TODAY...AND A FEW SPECIAL MARINE WARNINGS FOR GALE-
FORCE WIND GUSTS ARE POSSIBLE AROUND THE KEYS TODAY. A LARGE HIGH
WILL INTENSIFY OVER THE EASTERN UNITED STATES AND ADJACENT ATLANTIC
TODAY THROUGH WEDNESDAY...RESULTING IN FRESHENING EAST BREEZES ACROSS
KEYS COASTAL WATERS THIS AFTERNOON THROUGH THURSDAY. THE HIGH WILL
WEAKEN SLOWLY THURSDAY NIGHT THROUGH SATURDAY.
&&

.AVIATION...
SHOWERS AND THUNDERSTORMS WILL PRESS TO THE NORTHWEST FROM THE CAY
SAL BANK...REACHING THE MTH TERMINAL AROUND 12Z. ALTHOUGH CONFIDENCE
IS HIGH FOR BOTH TERMINALS...THE TIMING FOR EYW IS MUCH LESS CERTAIN
GIVEN THE CONVERGING STORMS FROM THE SOUTHWEST...SOUTH...AND
SOUTHEAST. EXPECT CONVECTIVE WIND GUSTS AS HIGHS AS 30 MPH...AND
TEMPORARY IFR CIG/VIS WITHIN LIKELY SHOWERS AND STORMS. PRECIPITATION
MAY LULL AFTER 18Z.
&&

.PRELIMINARY POINT TEMPS/POPS...
KEY WEST  86  79  87  79 / 70 60 50 50
MARATHON  85  79  87  79 / 70 60 50 50
&&

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

$$

PUBLIC/MARINE.........KASPER
AVIATION/NOWCASTS.....CLR

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