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000 FXUS62 KKEY 091943 AFDKEY AREA FORECAST DISCUSSION FOR THE FLORIDA KEYS NATIONAL WEATHER SERVICE KEY WEST FL 345 PM EDT SAT MAY 9 2009 .DISCUSSION... CURRENTLY - THE WEAK WESTERN PERIPHERY OF THE SURFACE ATLANTIC RIDGE EXTENDS ACROSS FLORIDA...AS HAS BEEN THE CASE FOR OVER A WEEK NOW. AS A RESULT MOSTLY LIGHT TO GENTLE EAST TO SOUTHEAST BREEZES HAVE BEEN OBSERVED OVER THE KEYS AND ALONG THE REEF. HEATING OVER SOUTH FLORIDA HAS ALLOWED THE FLOW NEARBY TO LIGHTEN UP SIGNIFICANTLY...WITH LONG KEY REPORTING SOUTH AT 6 KNOTS. WEAK...STABLE...AND DRY LOWER LEVEL FLOW HAS KEPT SKIES MOSTLY CLEAR TODAY...WITH NO PRECIPITATION ECHOES DETECTED IN THE KEYS AREA...AND SO FAR OVER SOUTH FLORIDA. HOWEVER...A FEW SHOWERS AND THUNDERSTORMS HAVE BEEN ABLE TO DEVELOP OVER ANDROS ISLAND. FORECAST - LITTLE CHANGE TO THE FORECAST IN THE SHORT TERM. DIURNAL OSCILLATIONS WILL CONTINUE TO DRIVE THE SURFACE FLOW ACROSS THE KEYS THROUGH THE NEXT SEVERAL DAYS DUE TO THE WEAK RIDGING TO OUR NORTH...AND ZONAL FLOW ALOFT. SATELLITE DERIVED PWAT IMAGERY AND MORE ACTIVITY OVER ANDROS THAN PRIOR DAYS INDICATE THAT A SWATH OF INCREASED LOWER LEVEL MOISTURE IS GRADUALLY SHIFTING WESTWARD TOWARDS OUR AREA. THIS IS CONSISTENT WITH GUIDANCE. WILL INSERT SLIGHT POPS FOR SUNDAY NIGHT. IN THE MEDIUM RANGE...A DYING COLD FRONT IS EXPECTED TO DRAPE ACROSS THE SOUTHEAST AND SAG INTO FLORIDA THE FIRST HALF OF NEXT WEEK. THIS WILL PINCH THE LOWER TROPOSPHERIC RIDGE...ALLOWING FOR A MORE BACKED FLOW. IN ADDITION GUIDANCE HAS BEEN CONSISTENT IN PICKING UP THE PWAT ABOUT .1 TO .2 INCHES. THIS WILL SET UP A MORE FAVORABLE ENVIRONMENT FOR BOTH CLOUD LINES AND MIGRATING SHOWERS AND BOUNDARIES OFF OF SOUTH FLORIDA. WITH THAT BEING SAID...CHANCE OF RAIN STILL APPEAR SLIGHT THROUGH THE MEDIUM INTO LONG TERM. IN THE LONG RANGE...UNCERTAINTY IS STILL A SIGNIFICANT FACTOR...BUT IT APPEARS THAT THE ATLANTIC RIDGE WILL GET A BOOST BY A NEW HIGH ROLLING OFF OF THE CONUS...AS A MORE AMPLIFIED FLOW BUILDS A MID AND UPPER LEVEL RIDGE ACROSS THE EASTERN STATES. IN RESPONSE...SURFACE WINDS SHOULD BECOME MORE EASTERLY AND MODERATE OVER THE SECOND HALF OF THE WEEK. && .MARINE... A WEAKENED RIDGE TO OUR NORTH WILL ALLOW DIURNAL HEATING AND COOLING OVER SOUTH FLORIDA AND CUBA TO ONCE AGAIN DOMINATE THE LOCAL FLOW REGIME. WINDS ARE EXPECTED TO PICK UP OUT OF THE EAST TO SOUTHEAST IN THE EVENINGS AND OVERNIGHT AFTER THE AFTERNOON LULL. THIS GENERAL PATTERN WILL PERSIST THROUGH THE FORECAST PERIOD. TOWARDS THE END OF THE FORECAST...WINDS ARE EXPECTED TO PICK UP FURTHER AS THE RIDGE TO OUR NORTH GETS REINFORCED...THUS TIGHTENING THE LOCAL PRESSURE GRADIENT. FOR NOW WILL HOLD WINDS SHY OF CAUTIONS. && .AVIATION... EXPECT VFR CONDITIONS AT THE KEY WEST AND MARATHON ISLAND TERMINALS THROUGH LATE THIS EVENING AND OVERNIGHT. ONLY A FEW SHALLOW CUMULUS ARE EXPECTED AOA FL025 AT ANY TIME. LIGHT TO GENTLE SOUTHEAST SURFACE BREEZES WILL BACK A LITTLE TOWARDS THE EAST LATE IN THE OVERNIGHT PERIOD. && .PRELIMINARY POINT TEMPS/POPS... KEY WEST 77 85 77 85 / 05 05 05 05 MARATHON 77 87 77 88 / 05 05 05 05 && .KEY WATCHES/WARNINGS/ADVISORIES... FL...NONE. GM...NONE. && $$ 11/04/TF VISIT US ON THE WEB AT WWW.WEATHER.GOV/KEYWEST