550 
 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