Area Forecast Discussion
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FXUS62 KKEY 031832
AFDKEY

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE KEY WEST FL
230 PM EDT FRI JUL 3 2015

.DISCUSSION....DISCUSSION...IN THE MID AND UPPER LEVELS...(700-200
MB)...LATEST AVAILABLE IR IMAGERY OVERLAID WITH MODEL STREAMLINE
ANALYSIS AS OF 200 PM DETAILS A DEVELOPING SHORT WAVE ACROSS THE
UPPER MISSISSIPPI VALLEY EMBEDDED WITHIN LARGE SCALE LOW AMPLITUDE
TROUGHING ENCOMPASSING THE EASTERN TWO THIRDS OF THE CONUS. MID AND
UPPER RIDGING IS CONFINED TO THE SOUTHWESTERN UNITED STATES...WHERE
A RIDGE AXIS REMAINS ORIENTED FROM NEVADA TO SOUTH TEXAS. ACROSS THE
LOWER LATITUDES AND CLOSER TO THE FLORIDA...THERE IS A TROUGH
PRESENT FROM THE SOUTHEAST GULF OF MEXICO AND THE YUCATAN PENINSULA.
TO THE EAST OF THAT EXISTS A REGIONAL SCALE RIDGE OVER THE NORTHERN
BAHAMAS. ISOLATED TO SCATTERED SHOWERS AND STORMS HAVE DEVELOPED
THIS AFTERNOON ACROSS THE NORTHWEST BAHAMAS AND THE UPPER
KEYS AND SURROUNDING WATERS...WHICH ARE BETWEEN THESE TWO
AFOREMENTIONED FEATURES THAT ARE UNDERNEATH RESULTANT WEAK UPPER
DIFFLUENT FLOW.

AT THE SURFACE AND IN THE LOWER TO MID LEVELS...SURFACE TO 700
MB...AS OF 200 PM THIS AFTERNOON...A NEAR 1020 MB SURFACE RIDGE
REMAINS ORIENTED FROM THE WEST CENTRAL ATLANTIC TO ACROSS THE
CENTRAL FLORIDA PENINSULA. LOW LEVEL CONFLUENT FLOW REMAIN IN PLACE
ACROSS THE KEYS SERVICE AREA. THE MORNING SOUNDING WAS
MOIST WITH MODERATE TO GENTLE EAST SOUTHEASTERLIES...AND COLUMNAR
PWAT AT 1.86 INCHES.

.CURRENTLY...AS OF 200 PM...SKIES ARE MOSTLY SUNNY ACROSS THE
ISLANDS...WITH RADAR DETECTING JUST ISOLATED SHOWERS AND
THUNDERSTORMS ACROSS THE ISLANDS AND ADJOINING WATERS ATTM.
TEMPERATURES HAVE REACHED 90 DEGREES OR HIGHER ACROSS ALL OF THE
ISLANDS WITH VERY UNCOMFORTABLE DEWPOINTS IN THE UPPER 70S. C-MAN
STATIONS ARE EAST TO SOUTHEAST NEAR 10 KNOTS ALONG THE REEF AND IN
FLORIDA BAY. A SEEMINGLY SOUND REPORT OF NEAR 15 KNOTS WAS RECEIVED
FROM A VESSEL IN THE OUTER FLORIDA STRAITS.


.SHORT TERM...TONIGHT THROUGH SUNDAY NIGHT...INCLUDING INDEPENDENCE
DAY...THE COMBINATION OF THE MID AND UPPER FEATURES WILL CONTINUE TO
RESULT IN LOWER LEVEL CONFLUENT FLOW UPSTREAM OF THE KEYS THROUGH
THIS EVENING. AT THE MOMENT COVERAGE IS ISOLATED...BUT THINK THAT
GIVEN INSTABILITY EXPECT DEVELOPMENT OF SCATTERED COVERAGE OF
SHOWERS AND THUNDERSTORMS LATE IN THE AFTERNOON AND THIS EVENING.
AFTER THAT...A EXPANSIVE AREA OF VERY DRY AIR ABOVE 850 MB WILL
ENCROACH UPON THE EAST OF THE KEYS FOR THE HOLIDAY WEEKEND AND
EARLY NEXT WEEK. ALTHOUGH STABILITY SHOULD INCREASE...WILL
CONTINUE TO MAINTAIN ISOLATED POPS IN THE GRIDS...UNLESS MODEL
FORECAST CYCLES LOWER PWAT DOWN BELOW 1.25 INCHES. THE PROXIMITY OF
SURFACE RIDGING WILL ONLY ALLOW GENTLE TO MODERATE BREEZES ACROSS
THE WATERS...WITH THE EXCEPTION OF THE FLORIDA STRAITS WHERE
MODERATE TO OCCASIONALLY FRESH BREEZES MAY BE ENCOUNTERED...GIVEN
BROAD LOWER SURFACE PRESSURE ACROSS THE WESTERN CARIBBEAN...TYPICAL
AT THIS TIME OF THE YEAR. GIVEN MOSTLY CLEAR SKIES AND THESE
BREEZES...MAXIMUM AND MINIMUM TEMPERATURES WILL REMAIN A FEW DEGREES
ABOVE SEASONAL VALUES AT THIS TIME OF YEAR...AND CHANCES FOR A
RECORD HERE AND THERE REMAIN GOOD.

EXTENDED...MONDAY THRU FRIDAY...NOT MUCH NOTICEABLE DIFFERENCE
APPEARS IN ALL OF THE AVAILABLE LARGE SCALE MODELS DATA AT THIS
RANGE. ADDITIONAL SAHARAN DUST WILL BE TRANSPORTED UPSTREAM ABOVE
850...AND THIS IS VERY EVIDENT IN THE CIMMS SATELLITE PRESENTATION
WHICH SHOWS THAT PREPONDERANCE OF THIS AIRMASS AL THE WAY UPSTREAM
TO THE AFRICAN CONTINENT. GIVEN THE POSITION OF THE RIDGING...WILL
CONTINUE WITH SAME WINDS AND TEMPERATURE FORECAST ATTM.

&&

.MARINE...GENTLE TO MODERATE BREEZES EXPECTED ACROSS THE WATERS WITH
THE EXCEPTION OF THE FLORIDA STRAITS SATURDAY NIGHT THRU SUNDAY
NIGHT...WHERE ENOUGH OF A GRADIENT WILL GENERATE MODERATE TO FRESH
PERIODS OF WIND VELOCITY. SCEC IS NOT ADVERTISED FOR THOSE 3
PERIODS AS WE HAVE 15 KNOTS AND GUSTY...BUT IT REMAINS A DISTINCT
POSSIBILITY.


&&

.AVIATION...VFR CONDITIONS WILL PREVAIL TONIGHT AT THE ISLAND
TERMINALS. THERE WILL BE ONLY A SLIM CHANCE FOR BRIEF MVFR
CONDITIONS AT THE ISLAND TERMINALS. SURFACE WINDS WILL BE LIGHT OUT
OF THE EAST SOUTHEAST.

&&

.PRELIMINARY POINT TEMPS/POPS...
KEY WEST  81  91  82  90 / 30 20 20 20
MARATHON  81  93  82  91 / 30 20 20 20

&&

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

$$

PUBLIC/MARINE.........FUTTERMAN
AVIATION/NOWCASTS.....11
DATA COLLECTION.......VICKERY

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