704 
 WTNT44 KNHC 050837
 TCDAT4
 HURRICANE IVAN DISCUSSION NUMBER  11
 NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
 5 AM EDT SUN SEP 05 2004
  
 INFRARED SATELLITE IMAGERY AND A 0450Z TRMM OVERPASS SHOW THAT IVAN
 HAS DEVELOPED SUFFICIENT ORGANIZED CONVECTION AROUND THE WARM SPOT
 SEEN EARLIER TO NOW CALL IT AN EYE.  SATELLITE INTENSITY ESTIMATES
 ARE 77 KT FROM AFWA AND 65 KT FROM TAFB AND SAB.  THUS...IVAN IS
 UPGRADED TO A 65 KT HURRICANE.
 
 THE INITIAL MOTION IS NOW 280/18...AND THE SHORT-TERM MOTION MAY BE
 EVEN FASTER.  IVAN IS ON THE SOUTH SIDE OF A STRONG SUBTROPICAL
 RIDGE...AND THIS SHOULD LIKELY CONTINUE FOR THE NEXT 3-4 DAYS. 
 THIS PATTERN SHOULD ALLOW A GENERALLY WEST-NORTHWESTWARD MOTION FOR
 THE NEXT 3-4 DAYS...A SCENARIO SUPPORTED BY WELL-CLUSTERED TRACK
 GUIDANCE.  THE GUIDANCE REMAINS FAIRLY WELL-CLUSTERED AROUND A
 WEST-NORTHWEST MOTION ON DAY 5...BUT BY THAT TIME THERE ARE
 SIGNIFICANT DISAGREEMENTS ON THE SYNOPTIC PATTERNS OVER THE WESTERN
 ATLANTIC RANGING FROM THE NOGAPS SOLID-LOOKING RIDGE TO THE GFS
 BROAD POST-FRANCES TROUGH.  THE 120 HR POINT WILL CONTINUE A
 WEST-NORTHWEST MOTION...BUT THE CONFIDENCE IN THIS POINT HAS
 DECREASED.  THE NEW FORECAST TRACK IS NUDGED A LITTLE TO THE SOUTH
 OF THE PREVIOUS PACKAGE BASED MAINLY ON THE INITIAL POSITION.
  
 LARGE-SCALE GUIDANCE PREDICTS LIGHT VERTICAL SHEAR FOR THE NEXT 3-4
 DAYS...SO THERE IS NO OBVIOUS REASON WHY IVAN SHOULD NOT INTENSIFY
 FURTHER.  THE INTENSITY FORECAST FOLLOWS THIS PHILOSOPHY...AND IT
 IS POSSIBLE THERE COULD BE RAPID STRENGTHENING.  WITH THE FORECAST
 TRACK TAKING THE STORM OVER HISPANIOLA BETWEEN 96-120 HR...THE
 FORECAST INTENSITY IS CONSIDERABLY REDUCED.  THERE IS ALSO SOME
 UNCERTAINTY OF WHETHER THE SHEAR WILL REMAIN FAVORABLE AFTER
 96 HR...AS THE GFS IN PARTICULAR SHOWS THE UPPER-LEVEL WINDS
 BECOMING LESS FAVORABLE.
  
 AS NOTED EARLIER...BECAUSE OF THE TYPICAL TRACK FORECAST ERRORS AT
 4-5 DAYS...THE CENTER COULD EASILY PASS SOUTH...OR NORTH...OF THE
 ISLAND OF HISPANIOLA.
  
 FORECASTER BEVEN
  
 FORECAST POSITIONS AND MAX WINDS
  
 INITIAL      05/0900Z  9.7N  44.3W    65 KT
  12HR VT     05/1800Z 10.3N  47.1W    70 KT
  24HR VT     06/0600Z 11.3N  50.6W    75 KT
  36HR VT     06/1800Z 12.2N  54.1W    80 KT
  48HR VT     07/0600Z 13.1N  57.5W    85 KT
  72HR VT     08/0600Z 14.5N  63.5W    95 KT
  96HR VT     09/0600Z 17.0N  69.0W   105 KT
 120HR VT     10/0600Z 20.5N  73.5W    70 KT
  
  
 $$