TROPICAL STORM FAY FORECAST/ADVISORY NUMBER 12
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL AL062008
1500 UTC MON AUG 18 2008
AT 11 AM EDT...1500 UTC...A HURRICANE WARNING IS IN EFFECT FOR THE
SOUTHWESTERN COAST OF FLORIDA FROM FLAMINGO TO ANNA MARIA ISLAND.
A HURRICANE WARNING MEANS THAT HURRICANE CONDITIONS ARE EXPECTED
WITHIN THE WARNING AREA WITHIN THE NEXT 24 HOURS. PREPARATIONS TO
PROTECT LIFE AND PROPERTY SHOULD BE RUSHED TO COMPLETION.
AT 11 AM EDT...THE TROPICAL STORM WARNING ALONG THE FLORIDA EAST
COAST IS EXTENDED NORTHWARD TO COCOA BEACH. A TROPICAL STORM
WARNING IS IN EFFECT ALONG THE FLORIDA EAST COAST FROM COCOA BEACH
SOUTHWARD...AND ALONG THE FLORIDA WEST COAST EAST OF FLAMINGO...
INCLUDING LAKE OKEECHOBEE.
A TROPICAL STORM WARNING AND A HURRICANE WATCH ARE IN EFFECT FOR THE
FLORIDA KEYS FROM OCEAN REEF TO KEY WEST...INCLUDING THE DRY
TORTUGAS AND FLORIDA BAY. A HURRICANE WATCH REMAINS IN EFFECT FOR
THE FLORIDA MAINLAND EAST OF FLAMINGO TO CARD SOUND BRIDGE...AND
ALONG THE FLORIDA WEST COAST NORTH OF ANNA MARIA TO TARPON SPRINGS.
AT 11 AM EDT...1500 UTC...A TROPICAL STORM WATCH IS IN EFFECT ALONG
THE FLORIDA EAST COAST NORTH OF COCOA BEACH TO FERNANDINA BEACH.
A TROPICAL STORM WATCH IS IN EFFECT FOR THE NORTHWESTERN BAHAMAS.
AT 11 AM EDT...1500 UTC...THE GOVERNMENT OF CUBA HAS DISCONTINUED
ALL WARNINGS AND WATCHES FOR CUBA.
INTERESTS ELSEWHERE IN THE FLORIDA PENINSULA AND THE EASTERN GULF OF
MEXICO SHOULD MONITOR THE PROGRESS OF FAY.
TROPICAL STORM CENTER LOCATED NEAR 23.6N 81.5W AT 18/1500Z
POSITION ACCURATE WITHIN 30 NM
PRESENT MOVEMENT TOWARD THE NORTH-NORTHWEST OR 335 DEGREES AT 11 KT
ESTIMATED MINIMUM CENTRAL PRESSURE 1003 MB
MAX SUSTAINED WINDS 50 KT WITH GUSTS TO 60 KT.
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TROPICAL STORM FAY DISCUSSION NUMBER 12
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL AL062008
1100 AM EDT MON AUG 18 2008
THE CENTER OF FAY HAS MOVED INTO THE FLORIDA STRAITS. SATELLITE
IMAGERY AND RADAR DATA SHOW STRONG CONVECTIVE BANDING OVER THE
EASTERN SIDE OF THE STORM...BUT LITTLE ACTIVITY IN THE WESTERN
SEMICIRCLE. THIS ASYMMETRY IS LIKELY DUE TO WESTERLY VERTICAL
SHEAR AND DRY AIR ENTRAINMENT. AN AIR FORCE RESERVE HURRICANE
HUNTER AIRCRAFT MEASURED 850 MB FLIGHT-LEVEL WINDS OF 61 KT...WITH
RELIABLE-LOOKING SFMR WINDS OF 45-50 KT. BASED ON THIS AND
SIMILAR DOPPLER RADAR WINDS...THE INITIAL INTENSITY IS INCREASED TO
50 KT. THE LATEST MINIMUM PRESSURE REPORTED BY THE HURRICANE
HUNTER IS 1003 MB.
FAY HAS BEEN MOVING IN FITS AND STARTS FOR THE PAST COUPLE OF
DAYS...WITH THE CENTER MOVING FASTER TOWARD THE NORTH-NORTHWEST
DURING THE PAST 6 HR. THE INITIAL MOTION IS 335/11. FAY IS
ENTERING A BREAK IN THE SUBTROPICAL RIDGE OVER THE EASTERN GULF OF
MEXICO AND FLORIDA CAUSED BY A MID/UPPER-LEVEL TROUGH MOVING
THROUGH THE SOUTHEASTERN UNITED STATES. BEYOND 36-48 HR...THE
TROUGH IS FORECAST TO LIFT OUT...WITH A MID/UPPER-LEVEL RIDGE
BUILDING OVER THE EASTERN UNITED STATES AHEAD OF A SECOND TROUGH
OVER THE WESTERN GULF COAST STATES. MOST OF THE TRACK GUIDANCE
RESPONDS TO THIS EVOLUTION BY FORECASTING FAY TO MOVE GENERALLY
NORTHWARD NEAR OR OVER THE FLORIDA PENINSULA AND INTO THE EASTERN
UNITED STATES. HOWEVER...THE GFS AND ECMWF BOTH FORECAST FAY TO
TURN NORTHEASTWARD INTO THE ATLANTIC AND STALL BY 120 HR...WHILE
THE NOGAPS CONTINUES TO CALL FOR A MORE WESTERLY MOTION TOWARD THE
FLORIDA PANHANDLE. THE HYDROMETEOROLOGICAL PREDICTION CENTER NOTED
THAT THE GFS AND ECMWF ENSEMBLES ARE NOT IN GOOD AGREEMENT WITH THE
OPERATIONAL RUNS...SO THESE OUTLIERS ARE IGNORED FOR THE MOMENT.
THE NEW FORECAST TRACK WILL FOLLOW THE NORTHWARD SCENARIO...LYING
JUST A LITTLE TO THE EAST OF THE CONSENSUS MODELS AND THE CENTER OF
THE GUIDANCE ENVELOPE. THE TRACK BRINGS THE CENTER OVER THE
SOUTHWESTERN COAST OF FLORIDA IN A LITTLE OVER 24 HR.
FAY IS IN A MODERATE SOUTHWESTERLY VERTICAL SHEAR ENVIRONMENT...AND
THE UPPER-LEVEL WINDS WILL LIKELY REMAIN LESS THAN IDEAL FOR THE
NEXT 24-48 HR. THIS...COMBINED WITH THE DRY AIR AND THE CURRENT
STRUCTURE...WILL LIKELY PREVENT RAPID INTENSIFICATION. HOWEVER...
THE GUIDANCE SHOWS GRADUAL STRENGTHENING...WITH THE GFDL AND HWRF
MODELS MAKING FAY A HURRICANE BEFORE LANDFALL. THUS...THE
INTENSITY FORECAST WILL FOLLOW SUIT. AFTER LANDFALL...FAY SHOULD
SLOWLY WEAKEN AND BECOME A REMNANT LOW BY 120 HR. THIS INTENSITY
FORECAST IS LOW CONFIDENCE...AND THERE IS A DISTINCT CHANCE FAY
MIGHT NOT REACH HURRICANE STRENGTH BEFORE LANDFALL...ESPECIALLY IF
IT MOVES TO THE RIGHT OF THE FORECAST TRACK.
IT SHOULD BE NOTED THAT...SIMILAR TO CHARLEY IN 2004...SMALL
DEVIATIONS FROM THE FORECAST TRACK COULD MAKE LARGE DIFFERENCES IN
WHEN AND WHERE THE CENTER OF FAY MAKES LANDFALL.
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