Area Forecast Discussion
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000
FXUS62 KKEY 301827
AFDKEY

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE KEY WEST FL
227 PM EDT SUN AUG 30 2015

.DISCUSSION...
ANALYSIS OF SATELLITE AND RADAR DATA OVER THE LAST FEW HOURS
SUGGESTS THAT THE OVERALL VIGOR AND COVERAGE OF DEEP CUMULUS
CONVECTION HAS DECREASED SLIGHTLY ACROSS THE FLORIDA KEYS AND
ADJACENT COASTAL WATERS. THE LOCAL ATMOSPHERE LIKELY HAS STABILIZED
SOMEWHAT OWING TO WIDESPREAD RAIN AND ASSOCIATED COOLER AND
NEGATIVELY BUOYANT AIR AT LOW LEVELS. NEVERTHELESS...A LARGE CLUSTER
OF STRONG THUNDERSTORMS IS ONGOING OVER THE LOWER STRAITS OF FLORIDA
BETWEEN 20 AND 60 NAUTICAL MILES SOUTH-SOUTHWEST OF KEY WEST...WHILE
NEWLY DEVELOPING STORMS ALSO ARE PRESENT OVER PORTIONS OF CUBA AND
ITS ADJACENT WATERS. LOWER-TROPOSPHERIC MOISTURE CONVERGENCE SEEMS TO
HAVE WANED SLIGHTLY SINCE ITS PEAK EARLIER TODAY. HOWEVER...A VERY
MOIST AND CONFLUENT LOW-LEVEL PERSISTS...AND IT LIKELY WILL NOT TAKE
LONG FOR THE ATMOSPHERE TO DESTABILIZE GIVEN THE WARM SEA SURFACE
TEMPERATURES AND FRESH TO STRONG SOUTHERLY BREEZES.

CURRENTLY...MOST OF THE LOWER AND MIDDLE KEYS ARE RAIN-FREE...WHILE
IT IS RAINING LIGHTLY OR MODERATELY IN THE UPPER KEYS. SEE OUR MOST
RECENT PUBLIC INFORMATION STATEMENT...MIAPNSKEY...FOR THE LATEST
RAINFALL REPORTS ACROSS THE FLORIDA KEYS. AMOUNTS DURING THE LAST 24
HOURS RANGED FROM UNDER A HALF INCH IN MID-TOWN KEY WEST TO NEARLY
THREE INCHES IN PORTIONS OF KEY LARGO...WITH 100 PERCENT COVERAGE OF
MEASURABLE RAINFALL ACROSS THE KEYS. AIR TEMPERATURES HAVE RECOVERED
TO THE MID 80S IN THE LOWER AND MIDDLE KEYS...WITH DEWPOINT
TEMPERATURES IN THE MID 70S. WINDS HAVE GONE DUE SOUTH...BLOWING
STEADY FROM 15-20 MPH...WITH LOCALLY HIGHER GUSTS.

FORECASTS -- THE LOCAL WEATHER PATTERN OVER THE NEXT SEVERAL DAYS
WILL BE GOVERNED PRIMARILY BY A DEEP LAYER MEAN ANTICYCLONE CENTERED
OVER THE WESTERN SUBTROPICAL ATLANTIC BETWEEN BERMUDA AND THE
BAHAMAS. THIS SYSTEM WILL HOLD SWAY THROUGH AT LEAST EARLY
WEDNESDAY...BEFORE SLOWLY BREAKING DOWN DUE TO INCURSIONS OF CYCLONIC
VORTICITY FROM THE MIDLATITUDES. THE WEAKENING LOW-LEVEL
TROUGH AND CYCLONIC VORTICITY CENTER FROM THE REMNANTS OF ERIKA
GRADUALLY WILL MIGRATE NORTHWARD AND ELONGATE ALONG THE WESTERN
FLANK OF THE ATLANTIC SUBTROPICAL ANTICYCLONE FROM TONIGHT THROUGH
TUESDAY NIGHT. THEREFORE...RAIN AND THUNDERSTORM CHANCES WILL DROP
RAPIDLY FROM EAST TO WEST STARTING LATER TONIGHT. BY MONDAY
NIGHT...RAIN CHANCES MAY ACTUALLY DROP A BIT BELOW CLIMATOLOGY FOR A
FEW PERIODS WHILE THE SUBTROPICAL ANTICYCLONE BRINGS SOME SUBSIDENCE
AND DRIER AIR. HOWEVER...THIS PHASE WILL BE SHORT-LIVED...AND WE
RETURN 12-HOUR MEASURABLE RAIN CHANCES BACK TO PEAK EARLY SEPTEMBER
CLIMATOLOGCIAL VALUES OF 40 PERCENT.

BREEZY SOUTH WINDS OF 15 TO 20 MPH WILL SUBSIDE LATER THIS EVENING
THROUGH MONDAY...TURNING SOUTHEAST...THEN EAST CLOSER TO 10 MPH FOR
THE REST OF THE WEEK.
&&

.MARINE...
A SMALL CRAFT ADVISORY WILL REMAIN IN EFFECT FOR FLORIDA KEYS
COASTAL WATERS THIS EVENING. A TROUGH OF LOW PRESSURE OVER THE
EXTREME SOUTHEASTERN GULF OF MEXICO WILL LIFT NORTHWARD TONIGHT AND
MONDAY...WHILE A WEAK ATLANTIC HIGH PRESSURE RIDGE BUILDS BACK IN
ACROSS SOUTHERN FLORIDA...BRINGING LIGHTER BREEZES. AN AREA OF WEAK
HIGH PRESSURE THEN WILL REMAIN OVER OR NEAR THE FLORIDA PENINSULA
TUESDAY THROUGH THURSDAY. &&

.AVIATION...
COVERAGE OF SHOWERS AND THUNDERSTORMS HAVE DIMINISHED ACROSS THE
FLORIDA KEYS AND SIGNIFICANT IMPACTS ARE NOT EXPECTED THROUGH THE
AFTERNOON HOURS FOR NEITHER OF THE TERMINALS. HOWEVER...MVFR CIGS
WILL CONTINUE FOR MARATHON AS AN AREA OF STRATIFORM RAIN DRIFTS
NORTHWEST DURING THE NEXT FEW HOURS. WINDS WILL RELAX A BIT LATER
TONIGHT. FOR NOW...THEY WILL BE FROM THE SOUTH AT 10 TO 15 KNOTS WITH
GUSTS UP TO 25 KNOTS.
&&

.CLIMATE...
ON THIS DATE IN KEYS WEATHER HISTORY...IN 1891...THE DAILY RECORD
RAINFALL OF 3.76" WAS RECORDED. PRECIPITATION RECORDS FOR KEY WEST
DATE BACK TO 1871.
&&

.PRELIMINARY POINT TEMPS/POPS...
KEY WEST  78  88  82  90 / 70 50 30 30
MARATHON  78  89  82  92 / 70 50 30 30
&&

.KEY WATCHES/WARNINGS/ADVISORIES...
FL...NONE.
GM...SMALL CRAFT ADVISORY IN EFFECT FOR GMZ031-GMZ032-GMZ033-
     GMZ034-GMZ035-GMZ042-GMZ043-GMZ044-GMZ052-GMZ053-GMZ054-
     GMZ055-GMZ072-GMZ073-GMZ074-GMZ075.
&&

$$

PUBLIC/MARINE.........KASPER
AVIATION/NOWCASTS.....KN
DATA COLLECTION.......FLING
COORDINATOR...........RIZZO

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