AFDEYW

FLORIDA KEYS AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE KEY WEST FL
315 AM EDT TUE OCT 3 2006

.DISCUSSION...
A FRESH AND DEEP NORTHEAST FLOW PUSHING ACROSS VERY WARM ATLANTIC 
WATERS (MID 80S) IS GENERATING SCATTERED SHOWERS ACROSS THE FLORIDA 
STRAITS...WITH A FEW SHOWERS PASSING ACROSS UPPER KEYS COMMUNITIES. 
ELSEWHERE...ISOLATED SHOWERS ARE PENETRATING INTO THE FLORIDA 
BAY...WITH NO ACTIVITY IN THE GULF WATERS. LATEST SURFACE ANALYSIS 
DEPICTS AN ELONGATED AREA OF HIGH PRESSURE (1025 MB) CENTERED OVER 
EASTERN NORTH CAROLINA...WITH A BROAD TROUGH REACHING FROM THE 
WESTERN ATLANTIC ACROSS THE EXTREME SOUTHEAST BAHAMAS. THE PRESSURE 
DIFFERENCE BETWEEN THESE TWO FEATURES IS RESULTING IN NORTHEAST 
WINDS OF AROUND 20 KNOTS WITH GUSTS NEAR 30 KNOTS AT THE C-MAN 
STATION PLATFORMS. 

.FORECAST...(TODAY THROUGH THURSDAY)
A BROAD MID AND UPPER LEVEL TROUGH EXTENDING FROM JUST OFFSHORE OF 
THE MID ATLANTIC COAST...SOUTHWARD INTO THE BAHAMAS WILL SUPPORT A 
BROAD SURFACE TROUGH TO LINGER OVER THE NEXT SEVERAL DAYS. 
MEANWHILE...A SURFACE ANTICYCLONE OVER THE MID ATLANTIC COAST AND 
WESTERN ATLANTIC TODAY...WILL GRADUALLY WEAKEN AND SHIFT EASTWARD AS 
A COLD FRONT DROPS SOUTHEASTWARD INTO THE MID ATLANTIC COAST BY LATE 
THURSDAY. THE PRESSURE DIFFERENCE BETWEEN THESE FORMER TWO SYSTEMS 
WILL RESULT IN FRESH NORTHEAST WINDS THROUGH AT LEAST WEDNESDAY. IN 
ADDITION...WITH A DEEP NORTHEAST TO EAST FLOW...GFS FORECAST 
SOUNDINGS MAINTAIN PWAT VALUES OF AROUND 1.50 INCHES. GIVEN AMPLE 
MOISTURE AND CONDITIONAL INSTABILITY...LOW CHANCE POPS WILL BE KEPT 
THROUGH WEDNESDAY NIGHT. FOR THURSDAY...A MINOR MID AND UPPER LEVEL 
DISTURBANCE DROPPING DOWN THE FLORIDA PENINSULA MAY PROVIDE WEAK 
UPWARD VERTICAL MOTION TO ENHANCE MESOSCALE BOUNDARIES. HENCE...40 
PERCENT POPS WILL BE MAINTAINED. 

EXTENDED(THURSDAY NIGHT THROUGH MONDAY)
THE AFOREMENTIONED BROAD SURFACE TROUGH WILL LINGER NEAR THE WESTERN 
BAHAMAS...AS ANOTHER AREA OF HIGH PRESSURE REMAINS OVER THE EASTERN 
UNITED STATES. DESPITE NO DISCERNIBLE SUBSIDENCE OR LARGE SCALE 
ASCENT APPARENT...PLENTY OF LOW LEVEL MOISTURE WITHIN AN EASTERLY 
FLOW SHOULD GENERATE DIURNAL CLOUD LINES ALONG WITH SOME NOCTURNAL 
SHOWERS TO PUSH ACROSS THE ISLAND CHAIN. THEREFORE...SCATTERED POPS 
ALONG WITH NEAR NORMAL TEMPERATURES WILL BE MAINTAINED THROUGH THE 
PERIOD.

&&

.MARINE...
ALTHOUGH THERE WILL BE OCCASIONAL...BRIEF AND SUBTLE WIND LULLS 
ON KEYS WATERS...MOSTLY NORTHEAST WINDS OF NEAR 20 KNOTS WILL 
PERSIST THROUGH AT LEAST WEDNESDAY NIGHT. HENCE...A SMALL CRAFT 
ADVISORY IS EXPECTED TO REMAIN IN EFFECT THROUGH AT LEAST THE MIDDLE 
OF THIS WEEK. THEREAFTER...WINDS SHOULD BECOME MODERATE FOR THE 
LATTER PART OF THIS WEEK...WITH ANOTHER SLIGHT INCREASE IN NORTHEAST 
WINDS THIS WEEKEND.   

&&

.AVIATION...
VFR CONDITIONS WILL PREVAIL AT KEYW AND KMTH THROUGH AT LEAST THE 
NEXT 24 HOURS. SHORT-LIVED (30 MINUTES OR LESS) MVFR CONDITIONS ARE 
POSSIBLE AT KEYW AND KMTH EARLY THIS MORNING AND LATE TUESDAY NIGHT. 
DUE TO THE SHORT-LIVED NATURE OF POSSIBLE MVFR CONDITIONS...ONLY VFR 
CONDITIONS WILL BE ADVERTISED IN THE KEYW AND KMTH TAFS. CROSSWINDS 
AT KEYW AND KMTH WILL BE NEAR 10 KNOTS TODAY AND TONIGHT. 

LESS THAN 25% OF THE KMIA-KEYW FLIGHT ROUTE WILL BE AFFECTED BY MVFR 
CONDITIONS TODAY. CIRCUMNAVIGABLE IFR CONDITIONS EXPECTED ALONG THE 
KMIA-KEYW FLIGHT ROUTE TODAY. HEAVIER SHOWERS ALONG THE KMIA-KEYW 
FLIGHT ROUTE WILL PRODUCE WIND GUSTS NEAR 30 KNOTS TODAY. 

&&

.PRELIMINARY POINT TEMPS/POPS...
KEY WEST   88 80 88 80 / 30 30 30 30
MARATHON   89 81 88 80 / 30 30 30 30

&&

.KEY WATCHES/WARNINGS/ADVISORIES...SCA FOR ALL KEYS WATERS.

$$

APA
BS