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000
FXUS62 KKEY 030210
AFDKEY

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE KEY WEST FL
1010 PM EDT WED SEP 2 2015

.DISCUSSION...
AN UPPER-LEVEL COMPOSITE ANALYSIS THIS EVENING REVEALS A DEEP LAYER
MEAN ANTICYCLONE CENTERED RIGHT OVER THE SOUTHERN FLORIDA PENINSULA.
THE FLORIDA KEYS REMAIN JUST SOUTH OF THE ANTICYCLONE CENTER WITHIN
DEEP...BUT WEAK EASTERLY FLOW. IN FACT...THE SURFACE-TO-10000-FEET
LAYER MEAN FLOW WAS 070/05KT...PER DATA COLLECTED FROM THE KEY WEST
EVENING RADIOSONDE BALLOON. INCIDENTALLY...SOME OF THE LOWER-
TROPOSPHERIC THERMODYNAMIC DATA MAY NOT BE REPRESENTATIVE OF THE
AMBIENT ATMOSPHERIC ENVIRONMENT...ESPECIALLY IN THE LAYER 4000-7000
FEET ABOVE GROUND. THE BALLOON SEEMS TO HAVE PENETRATED A CUMULUS
CLOUD AT THESE ALTITUDES. IN ANY CASE...THE ATMOSPHERE REMAINS VERY
MOIST IN THE LOW LEVELS...WITH MODERATE CONDITIONAL INSTABILITY AND
LITTLE CONVECTIVE INHIBITION. THE LIMITING FACTORS FOR DEVELOPMENT OF
DEEP...MOIST CONVECTION ARE DRY AIR ENTRAINMENT AND LACK OF SURFACE-
BASED LIFT. HOWEVER...ISOLATED SHOWERS AND EVEN A FEW THUNDERSTORMS
HAVE FORMED DURING THE LAST SEVERAL HOURS WHERE SURFACE FORCING WAS
PRESENT. EVEN NOW...ISOLATED SHOWERS OF MODERATE TO HEAVY RAIN ARE
DRIFTING WESTWARD OVER PORTIONS OF THE SERVICE AREA.

CURRENTLY...AIR TEMPERATURES IN MOST KEYS ISLAND COMMUNITIES ARE IN
THE MID 80S...WITH DEWPOINT TEMPERATURES IN THE MID TO UPPER 70S.
HEAT INDICES AT THIS HOUR REMAIN IN THE MID 90S.

OVERNIGHT FORECASTS ARE ON TRACK. EXPECT PARTLY CLOUDY SKIES AND A
SLIGHT CHANCE OF SLOW-MOVING SHOWERS OR THUNDERSTORMS...LOW
TEMPERATURES IN THE LOWER 80S...AND LIGHT EAST WINDS. THE DIGITAL
FORECAST DATABASE HAS BEEN UPDATED...AND DERIVED PRODUCTS WILL BE
FORTHCOMING SHORTLY.
&&

.MARINE...
NO ADVISORIES AND NO HEADLINES. A WEAK HIGH PRESSURE CELL OVER THE
FLORIDA PENINSULA WILL DRIFT SOUTHWARD OVERNIGHT AND THURSDAY. THIS
HIGH PRESSURE CELL WILL BE NEAR THE FLORIDA KEYS FRIDAY AND SATURDAY.
GENERALLY LIGHT TO GENTLE BREEZES WILL PREVAIL OVERNIGHT THROUGH
MONDAY.
&&

.AVIATION...
THROUGH 03/24Z...PREVAILING VFR CONDITIONS ARE EXPECTED AT BOTH EYW
AND MTH. SCATTERED SHOWERS WITH MODERATE TO HEAVY PRECIPITATION AND
ISOLATED THUNDERSTORMS WITH HEAVY TO EXTREME PRECIPITATION WILL MOVE
ACROSS THE FLORIDA KEYS AND ADJACENT COASTAL WATERS FROM 070/06KT
THROUGH 03/12Z. HOWEVER...IFR/MVFR EVENT PROBABILITIES REMAIN TOO
LOW FOR INCLUSION IN TAFS. CELL MOTIONS WILL BECOME SLOWER AND MORE
VARIABLE/ERRATIC AFTER 03/12Z.
&&

.CLIMATE...
SEPTEMBER 2...ON THIS DATE IN FLORIDA KEYS WEATHER HISTORY...IN
1935...THE EYE OF THE LABOR DAY HURRICANE MOVED NORTHWEST ACROSS LONG
KEY AND LOWER MATECUMBE KEY IN THE EVENING... ACCOMPANIED BY A STORM
TIDE 15-20 FT ABOVE MEAN LOW WATER AND AN EYE LULL OF 55 MINUTES ON
LONG KEY. ENGINEERING STUDIES INDICATED GUSTS OF 150 TO 200 MPH FROM
LOWER MATECUMBE KEY TO ISLAMORADA. OVER 400 PEOPLE WERE KILLED...MANY
OF WHOM WERE WORLD WAR I VETERANS WORKING ON THE OVERSEAS
RAILROAD...WHICH WAS DESTROYED. IT WAS THE STRONGEST HURRICANE EVER
TO MAKE LANDFALL IN THE UNITED STATES. (SEE
HTTP://EN.WIKIPEDIA.ORG/WIKI/LABOR_DAY_HURRICANE FOR MORE
INFO./DETAILS.)
&&

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

$$

PUBLIC/MARINE.........KASPER
AVIATION/NOWCASTS.....KASPER
DATA COLLECTION.......FLING
MEDIA.................BS

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