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| #209790 (Received by flhurricane at: 5:00 AM 23.Aug.2008) TCDAT1 TROPICAL STORM FAY DISCUSSION NUMBER 31 NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL AL062008 500 AM EDT SAT AUG 23 2008 RADAR AND SURFACE DATA INDICATE THAT THE CENTER OF FAY MADE LANDFALL ABOUT 0600 UTC JUST SOUTHWEST OF CARRABELLE FLORIDA. THE LATEST IMAGERY FROM THE WSR-88D IN TALLAHASSEE SHOWS A DECREASE IN CONVECTION NEAR THE CENTER...AND AN INCREASE ON CONVECTION BANDING AWAY FROM THE CENTER IN THE EASTERN SEMICIRCLE. THERE ARE NO RECENT OBSERVATIONS OF SUSTAINED TROPICAL-STORM FORCE WINDS FROM EITHER LAND OR MARINE STATIONS...SO THE INTENSITY IS A LITTLE UNCERTAIN. BASED MAINLY ON DOPPLER WIND VELOCITIES...THE INITIAL INTENSITY IS DECREASED TO 40 KT. IT SHOULD BE NOTED THAT DOPPLER WINDS OF NEAR 65 KT HAVE BEEN OBSERVED OVER LAND TO THE NORTH OF THE CENTER...BUT SURFACE OBSERVATIONS SUGGEST THESE WINDS ARE NOT MIXING DOWN TO THE SURFACE AT THIS TIME. THE INITIAL MOTION IS A SOMEWHAT ERRATIC 275/6...AS THE CENTER OCCASIONALLY SURGES AHEAD FOLLOWED BY PERIODS OF LITTLE MOVEMENT. FAY REMAINS SOUTH OF A LOW/MID-LEVEL RIDGE OVER THE EASTERN UNITED STATES. THE LARGE-SCALE MODELS SUGGEST THIS RIDGE SHOULD WEAKEN AFTER 24-48 HR AS A DEEP-LAYER TROUGH MOVES THROUGH THE NORTHERN UNITED STATES. AT THE SAME TIME...A LOW/MID-LEVEL RIDGE IS FORECAST TO DEVELOP NEAR OR OVER THE FLORIDA PENINSULA. THIS EVOLUTION SHOULD STEER FAY WESTWARD FOR 48-72 HR...THEN STEER THE CYCLONE SLOWLY NORTHEASTWARD. WHILE THE TRACK GUIDANCE GENERALLY AGREES WITH THIS SCENARIO...AFTER 48 HR THERE IS A CONSIDERABLE SPREAD IN THE SPEED OF THE NORTHEAST MOVEMENT. THE GFS AND ECMWF ARE THE FASTEST WITH THIS MOTION...WHILE THE HWRF...WHICH FORECASTS FAY TO MAKE A LOOP OVER SOUTHEASTERN LOUISIANA...IS THE SLOWEST. THE NEW FORECAST TRACK IS AN UPDATE OF THE PREVIOUS TRACK THROUGH 72 HR...THEN CALLS FOR A MOTION SLIGHTLY FASTER AND TO THE RIGHT OF THE PREVIOUS FORECAST. THE LATTER PART OF THE FORECAST IS ON THE LEFT SIDE OF THE GUIDANCE ENVELOPE AND SLOWER THAN THE MODEL CONSENSUS. FAY WILL REMAIN IN A GENERALLY FAVORABLE UPPER-LEVEL WIND ENVIRONMENT FOR THE NEXT 48-72 HR...SO THE INTENSITY WILL BE CONTROLLED MAINLY BY HOW MUCH LAND THE STORM ENCOUNTERS. ON THE FORECAST TRACK...ENOUGH OF THE CIRCULATION WILL BE OVER WATER FOR THE NEXT 72 HR TO MAINTAIN FAY AS A TROPICAL STORM...AND THIS IS REFLECTED IN THE INTENSITY FORECAST. THERE IS A CHANCE THE STORM COULD BE STRONGER THAN FORECAST IF IT GOES SOUTH OF THE FORECAST TRACK. AFTER 72 HR...FAY SHOULD BE FAR ENOUGH INLAND AND IN ENOUGH VERTICAL WIND SHEAR TO CAUSE IT TO DECAY TO A REMNANT LOW. REGARDLESS OF ITS EXACT TRACK...FAY WILL BE MOVING RATHER SLOWLY DURING THE NEXT SEVERAL DAYS...POSING A SIGNIFICANT HEAVY RAINFALL AND FLOOD HAZARD TO A VERY LARGE AREA. FORECAST POSITIONS AND MAX WINDS INITIAL 23/0900Z 29.9N 84.9W 40 KT...INLAND 12HR VT 23/1800Z 30.0N 86.0W 40 KT...OVER WATER 24HR VT 24/0600Z 30.3N 87.5W 40 KT...INLAND 36HR VT 24/1800Z 30.5N 89.1W 40 KT...INLAND 48HR VT 25/0600Z 30.5N 90.4W 35 KT...INLAND 72HR VT 26/0600Z 30.5N 91.0W 30 KT...INLAND 96HR VT 27/0600Z 32.1N 90.5W 25 KT...INLAND 120HR VT 28/0600Z 33.5N 89.5W 20 KT...INLAND REMNANT LOW $$ FORECASTER BEVEN |
