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Tropical Storm IVAN (Text)

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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
 
 
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