Area Forecast Discussion
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000
FXUS62 KKEY 211423
AFDKEY

AREA FORECAST DISCUSSION FOR THE FLORIDA KEYS
NATIONAL WEATHER SERVICE KEY WEST FL
930 AM EST SAT NOV 21 2009

.DISCUSSION...IN THE MIDDLE AND UPPER LEVELS...700-200 MB...LATEST
WATER VAPOR AVAILABLE SATELLITE IMAGERY OVERLAID WITH STREAMLINE
ANALYSIS AS OF 9 AM CONTINUE TO DEPICT A SPLIT FLOW PATTERN ACROSS
THE CONUS. A NEAR 100 KNOT JET AT 250 MB TRAVERSES THE SOUTHERN
PORTION OF NORTH AMERICA AS IT MOVES ACROSS BAJA...NORTHERN
MEXICO...THEN NORTHEASTWARD TO THE CAROLINAS. A DISORGANIZED UPPER
LOW OVER OKLAHOMA DIVES THE NORTHERN STREAM FROM THE SOUTHERN STREAM
OF THE OF THE JET. THE FLORIDA KEYS ARE BENEATH A WIDE BAND OF THE
SOUTHERN JETSTREAM...WITH CIRRUS MOVING OVERHEAD

IN THE LOWER TO MIDDLE LEVELS...SURFACE TO 700 MB...LATEST IR
SATELLITE IMAGERY OVERLAID WITH AVAILABLE SURFACE AND MARINE
OBSERVATIONS DETAIL A 1008 MB LOW OVER THE NORTHWESTERN GULF OF
MEXICO. A WARM FRONT IS ANALYZED EASTWARD TOWARD THE FLORIDA
PENINSULA...WHILE A COLD FRONT SWINGS SOUTH FROM THE SYSTEM TO
CENTRAL MEXICO. AS A RESULT...THE 12Z SOUNDING THIS MORNING
ILLUSTRATES A GENTLE BUT MOISTENING EAST TO SOUTHEAST FLOW FROM THE
SURFACE TO ABOUT 10000 FEET...WITH PWAT(PRECIPITABLE WATER) THAT HAS
RISEN IN 24 HOURS FROM 1.46 INCHES OR ALMOST 1.5 INCHES FROM ONLY
1.08 INCHES YESTERDAY MORNING. ENOUGH ISENTROPIC LIFT IS AVAILABLE
ALONG THE 300K SURFACE...WITH ISOLATED SHOWERS DELIVERING BRIEF
PERIODS OF LIGHT RAIN FALLING FROM CLOUD BASES BETWEEN 4000 AND 5000
FEET.

.CURRENTLY...AS OF 900 AM...SKIES ARE PARTLY CLOUDY OVER THE ISLANDS
AND ADJOINING WATERS. KEY WEST RADAR SCANS SHOW A DWINDLING AREA OF
LIGHT SHOWERS CONFINED TO THE WATERS WITHIN 30 NM OFFSHORE OF THE
FLORIDA REEF BETWEEN SOMBRERO KEY LIGHT AND EAST SAMBO LIGHT.
TEMPERATURES ARE PRESENTLY IN THE MID TO UPPER 70S WITH DEWPOINTS IN
THE LOWER 70S. C-MAN STATIONS ALONG THE REEF ARE REGISTERING
NORTHEAST TO SOUTHEAST WINDS AROUND 10 KNOTS...EXCEPT 10 TO 15 KNOTS
OUT AT PULASKI SHOAL LIGHT.

.SHORT TERM (REST OF TODAY)...IN THE MIDDLE AND UPPER
LEVELS...(700-200 MB)...ALL LARGE SCALE MODELS SLIDE THE LOW
PRESSURE AREA OVER THE SOUTHERN PLAINS EASTWARD AND FILL A FEW
DECAMETERS THROUGH 00Z. JUST A FEW CIRRUS CLOUDS WILL BE TRANSPORTED
OVER THE KEYS THRU THE DAY.

IN THE LOWER TO MID LEVELS...SURFACE TO 700 MB...THE WEAK SURFACE
LOW OVER THE NORTHWEST GULF WILL CONTINUE TO MOVE NORTHEASTWARD TO
JUST OFF THE LOUISIANA COAST BY DAYS END. DRYER AIR IN THE MIDDLE
LEVELS WILL GRADUALLY FILTER ACROSS THE KEYS FROM THE EAST LATER
THIS MORNING...PUTTING AN END TO ANY CHANCE FOR MEASURABLE RAIN
TODAY. TEMPERATURES AND HUMIDITY LEVELS WILL CONTINUE TO BE SLIGHTLY
ABOVE NORMAL...REACHING INTO THE LOWER 80S. WILL JUST DO A LAST
MINUTE UPDATE THIS MORNING TO TAKE OUT TRANSITIONAL WORDING AND
REMOVE SHOWER THREAT OVER THE ISLANDS.

&&

.MARINE...LIGHT TO GENTLE WINDS WILL INCREASE TO GENTLE TO MODERATE
THIS AFTERNOON AND TONIGHT


&&

.AVIATION...THROUGH 22/12Z...PREVAILING VFR CONDITIONS ARE EXPECTED
AT EYW AND MTH. A FEW LIGHT SHOWERS IN THE VICINITY OF EYW THIS
MORNING SHOULD DISSIPATE BY 15Z.


&&

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

$$

PUBLIC/MARINE/GRIDS............FUTTERMAN
AVIATION/NOWCASTS..............KASPER
DATA ACQUISITION/UPPER AIR.....ROSS


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