Area Forecast Discussion
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000
FXUS62 KKEY 040237
AFDKEY

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE KEY WEST FL
1037 PM EDT THU SEP 3 2015

.DISCUSSION...
AN UPPER-LEVEL COMPOSITE ANALYSIS THIS EVENING REVEALS A DEEP LAYER
MEAN ANTICYCLONE CENTERED NEARLY DIRECTLY OVERHEAD. THE CENTER
POSITION HAD MOVED JUST A LITTLE SOUTH FROM YESTERDAY AT THIS TIME.
NOT SURPRISINGLY...THE MEAN SEA LEVEL PRESSURE PATTERN LOCALLY IS
QUITE WEAK WITH LIGHT AND VARIABLE BREEZES PREVAILING. LOWER-
TROPOSPHERIC FLOW IS LIGHT OUT OF THE NORTHEAST ON AVERAGE. DATA FROM
THE KEY WEST EVENING RADIOSONDE BALLOON INDICATED A MODERATELY
UNSTABLE ATMOSPHERE WITH MODERATE CONVECTIVE INHIBITION AS WELL. IN
ADDITION...SOME DRY POCKETS WERE EVIDENT AT BOTH AT LOWER- AND MID-
TROPOSPHERIC ALTITUDES. SO...LIMITING FACTORS FOR DEEP...MOIST
CONVECTION ARE SIMILAR TO LAST NIGHT -- LACK OF SURFACE FORCING AND
DRY AIR ENTRAINMENT. STILL...ISOLATED SHOWERS AND EVEN A FEW
THUNDERSTORMS HAVE BEEN ABLE TO DEVELOP...MAINLY ALONG BOUNDARIES
ASSOCIATED WITH EITHER DIFFERENTIAL HEATING OR CONVECTIVE OUTFLOW.

CURRENTLY...AIR TEMPERATURES IN MOST KEYS ISLAND COMMUNITIES ARE NEAR
86F...WITH DEWPOINT TEMPERATURES IN THE MID 70S. HEAT INDICES REMAIN
IN THE MID 90S. WINDS ARE NEAR CALM OR LIGHT AND VARIABLE.

OVERNIGHT FORECASTS ARE ON TRACK...WITH NO UPDATES NECESSARY.
&&

.MARINE...
NO ADVISORIES AND NO HEADLINES. A HIGH PRESSURE AREA OVER THE
FLORIDA KEYS WILL WEAKEN OVERNIGHT...WHILE A TROUGH EXTENDS ACROSS
THE FLORIDA PENINSULA ON FRIDAY. A WEAK PRESSURE GRADIENT WILL HELP
MAINTAIN LIGHT TO GENTLE BREEZES ACROSS FLORIDA KEYS COASTAL WATERS
FROM SATURDAY THROUGH TUESDAY.
&&

.AVIATION...
OVERNIGHT...VFR CONDITIONS WILL PREVAIL AT BOTH THE KEY WEST AND
MARATHON INTERNATIONAL AIRPORT TERMINALS. SURFACE WINDS AT BOTH
TERMINALS WILL BE LIGHT AND VARIABLE.
&&

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

$$

PUBLIC/MARINE.........KASPER
AVIATION/NOWCASTS.....FUTTERMAN
DATA COLLECTION.......FLING

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