793 
 WTNT41 KNHC 300833
 TCDAT1
 HURRICANE FRANCES DISCUSSION NUMBER  22
 NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
 5 AM EDT MON AUG 30 2004
  
 THE LATEST DATA FROM AN AIR FORCE RESERVE HURRICANE HUNTER
 MONITORING FRANCES INDICATES THAT THE CENTRAL PRESSURE HAS RISEN TO
 958 MB AND THAT THE MAXIMUM 700 MB FLIGHT-LEVEL WINDS ARE 99 KT. 
 THIS WOULD SUPPORT AN INTENSITY 90 KT.  HOWEVER...THE LAST FEW
 SATELLITE IMAGES SHOW A BETTER ORGANIZED CYCLONE...AND SATELLITE
 INTENSITY ESTIMATES ARE 115 KT FROM TAFB AND 102 KT FROM SAB.  THE
 INITIAL INTENSITY IS REDUCED TO 105 KT...AND FOR THE MOMENT THIS
 MAY BE GENEROUS.  THE AIRCRAFT DATA ALSO INDICATES TWO WELL-DEFINED
 OUTER WIND MAXIMA.
 
 THE INITIAL MOTION IS 275/9.  FRANCES REMAINS ON THE SOUTH SIDE OF A
 SUBTROPICAL RIDGE AND SHOULD CONTINUE TO DO SO FOR ABOUT 72 HR. 
 BEYOND THAT TIME...MOST LARGE-SCALE MODELS AGREE THAT THE RIDGE
 SHOULD WEAKEN.  THIS PATTERN SHOULD MOVE FRANCES BASICALLY WESTWARD
 TO WEST-NORTHWESTWARD FOR 48-72 HR...FOLLOWED BY A GRADUAL
 NORTHWESTWARD TURN.  THE SYNOPTIC SURVEILLANCE MISSION FLOWN
 EARLIER TONIGHT SEEMS TO HAVE HELPED THE MODELS COME INTO BETTER
 AGREEMENT...AS THE GFS AND UKMET HAVE SHIFTED SOMEWHAT TO THE RIGHT
 OF THEIR PREVIOUS TRACKS.  THE OFFICIAL FORECAST IS A LITTLE SOUTH
 OF THE PREVIOUS TRACK FOR THE FIRST 36-48 HR AND ALONG THE SOUTHERN
 EDGE OF THE GUIDANCE...AS THE RIDGE TO THE NORTH MAY NOT ALLOW AS
 MUCH NORTHWARD MOTION EARLY ON AS INDICATED BY THE MODELS.  AFTER
 72 HR...THE TRACK IS DOWN THE CENTER OF THE MAIN DYNAMICAL MODEL
 GUIDANCE.  IT SHOULD BE NOTED THAT THE CANADIAN MODEL STILL CALLS
 FOR A MORE WESTERLY TRACK TOWARD THE FLORIDA KEYS OR SOUTH FLORIDA.
  
 FRANCES MAY HAVE BEEN SUFFERING SOME SOUTHERLY SHEAR WHICH HAS
 RESULTED IN THE OBSERVED WEAKENING.  THE SHIPS MODEL FORECASTS THE
 SHEAR TO WEAKEN DURING THE NEXT 36-48 HR...AND BOTH SHIPS AND THE
 GFDL FORECAST STRENGTHENING DURING THAT TIME.  THE INTENSITY
 FORECAST FOLLOWS SUIT...AND IT WOULD NOT BE A BIG SURPRISE IF
 FRANCES GOT STRONGER THAN THE 115 KT OFFICIAL FORECAST OR THE 121
 KT GFDL FORECAST.  THE SHIPS MODEL SHOWS INCREASING SHEAR AT 72 HR
 AND FORECASTS WEAKENING.  WHILE THIS IS POSSIBLE...THE INTENSITY
 FORECAST WILL NOT FOLLOW THIS UNTIL THERE IS A CLEARER SIGNAL.  ONE
 FLY IN THE INTENSITY FORECAST OINTMENT IS THE PRESENCE OF THE OUTER
 WIND MAXIMA...WHICH SUGGESTS CONCENTRIC EYEWALL CYCLES COULD OCCUR
 AND THROW OFF THE INTENSITY FORECAST.
  
 FORECASTER BEVEN
  
 FORECAST POSITIONS AND MAX WINDS
  
 INITIAL      30/0900Z 19.0N  57.3W   105 KT
  12HR VT     30/1800Z 19.1N  59.2W   105 KT
  24HR VT     31/0600Z 19.6N  62.0W   110 KT
  36HR VT     31/1800Z 20.2N  64.7W   115 KT
  48HR VT     01/0600Z 21.0N  67.4W   115 KT
  72HR VT     02/0600Z 22.5N  71.5W   115 KT
  96HR VT     03/0600Z 24.5N  75.0W   115 KT
 120HR VT     04/0600Z 27.0N  77.5W   115 KT
  
  
 $$