866 
 WTNT44 KNHC 061450
 TCDAT4
 HURRICANE IVAN DISCUSSION NUMBER  17
 NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
 11 AM EDT MON SEP 06 2004
 
 A SMALL EYE IS EVIDENT ON THE VISIBLE IMAGERY.  THERE IS A SMALL CDO
 AND SOMEWHAT RAGGED-LOOKING BANDING FEATURES.  ESTIMATES OF THE
 DATA T-NUMBER RANGE FROM 4.5 TO 5.5 SO THERE IS CONSIDERABLE
 UNCERTAINTY IN THE CURRENT INTENSITY.  SINCE THE HURRICANE APPEARED
 TO BE SO INTENSE LAST NIGHT...WE ARE HOLDING THE WIND SPEED AT 110
 KT IN GENERAL AGREEMENT WITH DVORAK RULES.  AN AIR FORCE HURRICANE
 HUNTER AIRCRAFT IS SCHEDULED TO INVESTIGATE IVAN AROUND 18Z AND
 THIS SHOULD PROVIDE A MUCH BETTER ESTIMATE OF THE STRENGTH OF THIS
 HURRICANE.  THE SHIPS GUIDANCE SHOWS SOME SLIGHT WESTERLY SHEAR IN
 THE ENVIRONMENT OF IVAN...PROBABLY DUE TO A WEAK UPPER-LEVEL LOW
 OVER THE EAST-CENTRAL CARIBBEAN.  HOWEVER THAT MODEL ALSO SHOWS
 INTENSIFICATION OF IVAN.  SINCE THE SHEAR IS NOT EXPECTED TO BECOME
 VERY HIGH...THE OFFICIAL FORECAST ALSO INDICATES INTENSIFICATION. 
 THE INTENSITY PREDICTION AT DAYS 4 AND 5 HAS THE ADDED UNCERTAINTY
 OF HOW IVAN WILL INTERACT WITH THE LAND MASSES OF HISPANIOLA AND
 EASTERN CUBA.
 
 INITIAL MOTION ESTIMATE IS SLIGHTLY NORTH OF DUE WEST...280/19. 
 THERE HAS BEEN LITTLE CHANGE TO THE TRACK FORECAST PHILOSPHY. IVAN
 IS EMBEDDED IN A WELL-DEFINED EASTERLY STEERING CURRENT AND SHOULD
 REMAIN SO OVER THE NEXT FEW DAYS.  LATE IN THE FORECAST
 PERIOD...THE MOTION OF THE HURRICANE WILL DEPEND ON THE STRENGTH
 AND POSITIONS OF A RIDGE OVER THE EXTREME SOUTHWEST ATLANTIC AND A
 TROUGH OVER THE EAST-CENTRAL UNITED STATES.  IT IS STILL TO EARLY
 TO CONFIDENTLY PREDICT WHETHER IVAN WILL BE SOUTH OF...OVER...OR
 NORTH OF CUBA AROUND 5 DAYS.  THE CURRENT NHC TRACK FORECAST IS
 VERY CLOSE TO THE LATEST DYNAMICAL MODEL CONSENSUS.  IT SHOULD BE
 NOTED THAT THE LATEST FSU SUPERENSEMBLE RUN IS TO THE SOUTH OF THE
 OFFICIAL TRACK BEYOND 3 DAYS.
 
 HURRICANE WARNINGS HAVE BEEN ISSUED FOR SEVERAL OF THE WINDWARD
 ISLANDS.
  
 FORECASTER PASCH
  
 FORECAST POSITIONS AND MAX WINDS
  
 INITIAL      06/1500Z 11.2N  53.4W   110 KT
  12HR VT     07/0000Z 11.8N  56.1W   115 KT
  24HR VT     07/1200Z 12.7N  59.5W   115 KT
  36HR VT     08/0000Z 13.7N  62.7W   120 KT
  48HR VT     08/1200Z 15.0N  65.5W   125 KT
  72HR VT     09/1200Z 17.5N  71.0W   125 KT
  96HR VT     10/1200Z 20.5N  75.0W    75 KT...INLAND
 120HR VT     11/1200Z 23.5N  78.5W    90 KT...OVER WATER
  
 $$