Area Forecast Discussion
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000
FXUS62 KKEY 220206
AFDKEY

AREA FORECAST DISCUSSION FOR THE FLORIDA KEYS
NATIONAL WEATHER SERVICE KEY WEST FL
1006 PM EDT TUE OCT 21 2014

.DISCUSSION...
BOTH SATELLITE AND SURFACE OBSERVATIONS THIS EVENING INDICATE
OVERCAST SKIES ACROSS MOST OF THE FLORIDA KEYS AND ADJACENT COASTAL
WATERS. MULTIPLE LAYERS IN THE ATMOSPHERE ARE POPULATED WITH NUMEROUS
CLOUD VARIETIES...INCLUDING PRECIPITATING ALTOSTRATUS AND A FEW
CUMULONIMBUS TOWERS OVER OVER THE STRAITS OF FLORIDA. AFTER A CLOUDY
AND RAINY DAY...MANY ISLAND COMMUNITIES ARE NOW RAIN-FREE. HOWEVER...
IT REMAINS DAMP AND MUGGY WITH BOTH AIR AND DEWPOINT TEMPERATURES IN
THE MID 70S. THE KEY WEST EVENING RAWINSONDE OBSERVATION INDICATED A
NEARLY SATURATED LAYER BETWEEN ABOUT 10000-25000 FEET ELEVATION...
WITH DRIER AIR BELOW. A MODERATELY UNSTABLE THERMODYNAMIC STRATIFICATION
WAS ANALYZED. HOWEVER...SIGNIFICANT CONVECTIVE INHIBITION ENERGY WAS
PRESENT AS A RESULT OF A RAIN-COOLED BOUNDARY LAYER. CONVECTIVE
INHIBITION ENERGY LIKELY IS MUCH LESS OVER THE WARMER WATERS
SURROUNDING THE KEYS WHERE AIR TEMPERATURES ARE HOVERING NEAR 80F.

LARGE-SCALE FORCING AT BOTH LOW AND HIGH ALTITUDES ASSOCIATED WITH
ISENTROPIC LIFT AND JET STREAM CIRCULATION...RESPECTIVELY...APPEARS
TO FAVOR CONTINUED DEEP ASCENT OVER THE SERVICE AREA OVERNIGHT. THIS
WILL LEAD TO FURTHER DESTABILIZATION OF TROPOSPHERIC COLUMNS AND
LOWERING OF CONVECTIVE INHIBITION IN AN ATMOSPHERE ALREADY NEAR
SATURATION. THE RESULT WILL BE THE LIKELY INCREASE IN RAIN...
SHOWER...AND THUNDERSTORM AREAS TOWARD DAYBREAK. OUR PRESENT
FORECASTS INDICATE A HIGH PROBABILITY OF MEASURABLE RAIN
OVERNIGHT...AND WE SEE NO REASON TO DEVIATE FROM THIS PROGNOSIS. THE
DIGITAL FORECAST DATABASE AND DERIVED TEXT AND GRAPHICS HAVE ALL BEEN
UPDATED...AND ARE AVAILABLE VIA THE USUAL CHANNELS.
&&

.MARINE...
THE COMBINATION OF A CONTINENTAL HIGH PRESSURE SYSTEM CENTERED OVER
THE EASTERN UNITED STATES AND A TROPICAL LOW PRESSURE AREA CENTERED
NEAR THE YUCATAN WILL MAINTAIN A RICH VEIN OF TROPICAL MOISTURE INTO
THE FLORIDA KEYS OVERNIGHT THROUGH FRIDAY. A NEARLY STATIONARY
FRONTAL ZONE JUST NORTH OF THE FLORIDA KEYS WILL PROVIDE THE FOCUS
FOR SEVERAL EPISODES OF HEAVY RAIN OVER SOUTHERN FLORIDA DURING THE
NEXT FEW DAYS. THE FRONTAL ZONE WILL MERGE WITH THE TROPICAL LOW
PRESSURE AREA IN THE VICINITY OF THE FLORIDA KEYS FRIDAY THROUGH
SUNDAY...RESULTING IN FRESHENING NORTHEAST TO EAST BREEZES ACROSS
ALL FLORIDA KEYS COASTAL WATERS.
&&

.AVIATION...
THROUGH 22/24Z...RAIN OR SHOWERS WILL BE PRESENT IN MORE
OBSERVATIONS THAN NOT. REDUCTIONS TO MVFR OR IFR WILL ONLY OCCUR
WITH THE MORE VIGOROUS SHOWERS OR THUNDERSTORMS...HOWEVER...WHICH
WILL BE DIFFICULT TO TIME. THE ONLY FEATURE OF NOTE ON RADAR AT THIS
TIME IS AN EXPANDING OUTFLOW BOUNDARY ACROSS THE STRAITS OF FLORIDA
WHICH IS SET TO IMPACT EYW BETWEEN 03Z AND 06Z. IMPACTS AT MTH FROM
THIS FEATURE ARE DOUBTFUL.
&&

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

$$

PUBLIC/MARINE.........KASPER
AVIATION/NOWCASTS.....MSB
DATA COLLECTION.......VICKERY

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