622 
 WTNT44 KNHC 032047
 TCDAT4
 TROPICAL STORM IVAN DISCUSSION NUMBER   5
 NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
 5 PM EDT FRI SEP 03 2004
  
 METEOSAT-8 VISIBLE IMAGERY DEPICTS A WELL-DEFINED CURVED BAND
 WRAPPING ABOUT TWO-THIRDS AROUND THE SYSTEM CENTER.  DVORAK T
 NUMBERS ARE 3.0 FROM BOTH TAFB AND SAB...AND THE INITIAL INTENSITY
 IS 45 KT BASED ON THESE ESTIMATES.  UPPER LEVEL OUTFLOW IS
 WELL-DEFINED AND EXPANDING IN ALL QUADRANTS...INDICATIVE OF WEAK
 VERTICAL SHEAR.  THE ENVIRONMENT APPEARS FAVORABLE FOR GRADUAL
 INTENSIFICATION THROUGHOUT THE FORECAST PERIOD.  THE OFFICIAL
 FORECAST CLOSELY FOLLOWS THE SHIPS GUIDANCE AND BRINGS IVAN TO
 HURRICANE INTENSITY IN 36 HOURS AND TO 100 KNOTS BY 120
 HOURS...WHICH IS LESS AGGRESSIVE THAN THE GFDL.
 
 IVAN IS MOVING A LITTLE MORE SOUTH OF DUE WEST...NOW 255/17.  THE
 TROPICAL STORM IS EMBEDDED WITHIN A DEEP EASTERLY CURRENT SOUTH OF
 A STRONG RIDGE.  THIS RIDGE IS FORECAST TO MOVE OR BUILD WESTWARD
 ALONG WITH IVAN FOR THE NEXT 72 HOURS OR SO...THEREFORE A GENERAL
 WESTWARD AND EVENTUALLY WEST-NORTHWESTWARD MOTION IS EXPECTED FOR
 THE NEXT SEVERAL DAYS.  THE NOGAPS AND GFDN TURN IVAN TO THE
 NORTHWEST WELL EAST OF THE LESSER ANTILLES...BUT THIS SCENARIO
 SEEMS LESS LIKELY GIVEN THE INITIAL MOTION.  THE OFFICIAL FORECAST
 IS IN BEST AGREEMENT WITH THE GFS AND GFDL MODELS...ON THE SOUTHERN
 SIDE OF THE GUIDANCE SUITE.
  
 FORECASTER KNABB/PASCH
  
 FORECAST POSITIONS AND MAX WINDS
  
 INITIAL      03/2100Z  8.9N  34.6W    45 KT
  12HR VT     04/0600Z  8.7N  37.1W    55 KT
  24HR VT     04/1800Z  8.7N  40.3W    60 KT
  36HR VT     05/0600Z  9.0N  43.4W    65 KT
  48HR VT     05/1800Z  9.8N  46.6W    75 KT
  72HR VT     06/1800Z 11.5N  53.0W    90 KT
  96HR VT     07/1800Z 13.0N  59.0W    95 KT
 120HR VT     08/1800Z 15.0N  64.5W   100 KT
  
  
 $$