000 WTNT41 KNHC 190255 TCDAT1 TROPICAL STORM FAY DISCUSSION NUMBER 14 NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL AL062008 1100 PM EDT MON AUG 18 2008 FAY'S ORGANIZATION HAS WAXED AND WANED THIS EVENING. THE STORM BECAME QUITE DISORGANIZED IN APPEARANCE ON WSR-88D RADAR OBSERVATIONS FROM KEY WEST AND MIAMI EARLIER THIS EVENING...AND THEN SHOWED INCREASED SPIRAL BANDING BUT NO CLOSED EYEWALL STRUCTURE. AIR FORCE HURRICANE HUNTER OBSERVATIONS SHOWED A FALL IN CENTRAL PRESSURE BUT NO INCREASE IN FLIGHT-LEVEL WINDS YET. THE TROPICAL CYCLONE IS EMBEDDED IN A DIFFLUENT UPPER-LEVEL FLOW ENVIRONMENT ON THE EAST SIDE OF A SHORT WAVE TROUGH OR CYCLONIC SHEAR AXIS AND THIS ENVIRONMENT IS ALSO IMPARTING MODEST SOUTHWESTERLY SHEAR OVER FAY. NONETHELESS...THERE IS STILL A CHANCE FOR FAY TO STRENGTHEN INTO A HURRICANE PRIOR TO CROSSING THE COAST TUESDAY MORNING. OUR FORECAST FOR FAY'S WEAKENING OVER THE PENINSULA MORE OR LESS FOLLOWS THE DECAY SHIPS MODEL. AIRCRAFT AND RADAR FIXES YIELD AN INITIAL MOTION NEAR 360/8. FAY IS MOVING BETWEEN A MID-LEVEL ANTICYCLONE TO ITS EAST AND A MID- TO UPPER-LEVEL TROUGH TO ITS WEST AND NORTHWEST. SOME OF THE DYNAMICAL TRACK GUIDANCE...SUCH AS THE GFDL...HWRF...AND U.K. MET OFFICE MODELS...HAVE SHIFTED A LITTLE TO THE EAST FOR FAY'S TREK ACROSS THE FLORIDA PENINSULA...SO THE OFFICIAL FORECAST WAS ALSO ADJUSTED SLIGHTLY TO THE RIGHT. AFTER 1-2 DAYS...GLOBAL MODELS INDICATE THAT THE STEERING PATTERN WILL BREAK DOWN AS A MID-TROPOSPHERIC RIDGE BUILDS OVER THE EASTERN U.S. AND BLOCKS THE FORWARD PROGRESS OF THE TROPICAL CYCLONE. THERE IS GREAT DIVERSITY IN THE OBJECTIVE TRACK FORECASTS FOR THE LATTER HALF OF THE PERIOD...AND THEREFORE LARGER THAN USUAL UNCERTAINTY AS TO WHERE FAY WILL EVENTUALLY GO. THE OFFICIAL TRACK FORECAST IS ROUGHLY IN THE MIDDLE OF THE HIGHLY SPREAD MODEL TRACKS. THE FORECAST OF FAY'S INTENSITY IN THE 72-120 HOUR TIME FRAME IS OF COURSE HIGHLY DEPENDENT ON HOW MUCH THE SYSTEM MOVES OVER WATER. SHOULD FAY REMAIN VERY NEAR OR OVER LAND...IT WOULD PROBABLY WEAKEN TO DISSIPATION SOONER THAN SHOWN HERE. FORECAST POSITIONS AND MAX WINDS INITIAL 19/0300Z 25.3N 81.9W 50 KT 12HR VT 19/1200Z 26.6N 81.7W 55 KT...INLAND 24HR VT 20/0000Z 28.1N 81.3W 40 KT...INLAND 36HR VT 20/1200Z 29.2N 81.0W 30 KT...INLAND 48HR VT 21/0000Z 30.3N 81.0W 40 KT 72HR VT 22/0000Z 31.0N 81.5W 45 KT...INLAND 96HR VT 23/0000Z 32.0N 82.5W 30 KT...INLAND 120HR VT 24/0000Z 32.0N 84.0W 20 KT...REMNANT LOW $$ FORECASTER PASCH/PASCH