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HURRICANE IVAN DISCUSSION NUMBER  16
NATIONAL WEATHER SERVICE MIAMI FL
5 AM EDT THU SEP 24 1998
 
THE DVORAK INTENSITY CLASSIFICATION FROM TAFB HAS INCREASED TO 4.5. 
SYSTEM HAS NOT BEGUN TO RECURVE YET SO THIS SUGGESTS THAT THERE MAY
BE TIME FOR SOME ADDITIONAL STRENGTHENING.  INITIAL INTENSITY IS SET
AT 70 KTS.  THE INTENSITY FORECAST GRADUALLY WEAKENS THE SYSTEM
BEFORE IT BECOMES EXTRA-TROPICAL AT 48 HOURS AS IT ENCOUNTERS 23/24C
SST/S.
 
THE INITIAL MOTION ESTIMATE IS 335/10 KNOTS. IVAN REMAINS INVOLVED
WITH AN UPPER-LEVEL TROUGH/LOW.  MOST OF THE TRACK MODEL GUIDANCE
IS IN FAIRLY CLOSE AGREEMENT SHOWING A GRADUAL TURN TOWARD THE
NORTH BY 24 HOURS...AND A BEND TOWARD THE NORTHEAST BY 48 HOURS.
 
FURTHER ANALYSIS OF THE LATE 18Z SHIP REPORT AND EARLIER REPORTS
FROM THE SAME SHIP...ID PJOX...REPORTING AN EAST WIND OF 75 KNOTS
LOCATED ABOUT 70 NM NORTHEAST OF IVAN AT THE TIME SUGGEST THAT THE
OBS ARE DOUBLE WHAT THEY SHOULD BE.  THUS 75 KT WIND IS REALLY 37
KTS. THIS FITS WITH COMPACT WIND FIELD AS ESTIMATED BY VISIBLE AND
SSM/I DATA.  THIS OB IS USED TO SET 34KT WIND RADIUS IN NE QUAD.   
 
JARVINEN
 
FORECAST POSITIONS AND MAX WINDS
 
INITIAL     24/0900Z 31.6N  41.6W    70 KTS
12HR VT     24/1800Z 32.9N  42.0W    70 KTS
24HR VT     25/0600Z 35.5N  41.2W    70 KTS
36HR VT     25/1800Z 37.7N  37.9W    65 KTS
48HR VT     26/0600Z 39.2N  33.0W    50 KTS...EXTRATROPICAL
72HR VT     27/0600Z 39.7N  19.3W    45 KTS...EXTRATROPICAL
 
 
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