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HURRICANE IVAN DISCUSSION NUMBER  20
NATIONAL WEATHER SERVICE MIAMI FL
5 AM EDT FRI SEP 25 1998
 
DVORAK SATELLITE CLASSIFICATIONS ARE 4.5 AND 4.0 FROM TAFB AND SAB
RESPECTIVELY.  THE INITIAL INTENSITY WILL BE MAINTAINED AT 70 KNOTS.
 
THE GRADUAL TURN TO THE NORTH FORECAST FOR THE LAST SEVERAL
PACKAGES HAS BEGUN WITH THE INITIAL MOTION ESTIMATE OF 040/14
KNOTS.  THE FORECAST TRACK HAS IVAN BENDING NORTHEAST WITHIN
24 HOURS THEN ACCELERATING TO THE EAST BY 36 HOURS. MOST OF
THE 06Z TRACK GUIDANCE IS CLUSTERED ON THIS SOLUTION.  THE SYSTEM
IS FORECAST TO GRADUALLY WEAKEN AND BECOME EXTRA-TROPICAL AS IT
HEADS EASTWARD ENCOUNTERING PROGRESSIVELY COOLER SSTS...24 DEG C
BY 36 HOURS...AND INCREASING NORTHWESTERLY VERTICAL WIND SHEAR.
 
THE SYSTEM COULD BRING TROPICAL STORM FORCE WINDS TO THE WESTERN
AZORES ON SATURDAY.
 
JARVINEN
 
FORECAST POSITIONS AND MAX WINDS
 
INITIAL     25/0900Z 35.7N  41.9W    70 KTS
12HR VT     25/1800Z 37.3N  40.2W    65 KTS
24HR VT     26/0600Z 38.6N  36.6W    60 KTS
36HR VT     26/1800Z 39.0N  31.6W    55 KTS...EXTRATROPICAL
48HR VT     27/0600Z 39.0N  25.3W    50 KTS...EXTRATROPICAL
72HR VT     28/0600Z 39.3N   9.0W    45 KTS...EXTRATROPICAL
 
 
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