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Hurricane FRANCES (Text)

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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
 
 
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