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TROPICAL DEPRESSION FOUR DISCUSSION NUMBER   6
NATIONAL WEATHER SERVICE MIAMI FL
4 AM EST FRI AUG 20 1999
 
AS IS THE CASE WITH NIGHT TIME IR THE CENTER OF THE TROPICAL
DEPRESSION IS DIFFICULT TO DETERMINE.  TAFB...SAB AND AIR FORCE
GLOBAL HAVE COME IN WITH POSITIONS A LITTLE SOUTH OF THE PREVIOUS
ONES.  HOWEVER...ALL OF THEIR POSITIONS ARE RELATIVELY CLOSE SO A
WEIGHTED MEAN WILL BE USED FOR THE INITIAL POSITION.
   
THE INITIAL MOTION ESTIMATE IS NOW 265/9.  MOST MODEL GUIDANCE
CONTINUES TO MOVE SYSTEM TOWARD THE WEST-NORTHWEST.  HOWEVER...GFDL
AND NOGAPS HAVE A MORE WESTERLY COMPONENT ALTHOUGH WITH SOMEWHAT
DIFFERENT SPEEDS.  OFFICIAL TRACK FORECAST IS STRONGLY WEIGHTED BY
THESE TWO MODELS AND SLIGHTLY SOUTH OF THE PREVIOUS FORECAST.

THE INTENSITY FORECAST REMAINS THE SAME AS THE PREVIOUS PACKAGE
BECAUSE OF EXPECTED SHEAR DURING THE FORECAST PERIOD.
 
JARVINEN
 
FORECAST POSITIONS AND MAX WINDS
 
INITIAL     20/0900Z 13.6N  24.7W    30 KTS
12HR VT     20/1800Z 13.5N  26.1W    30 KTS
24HR VT     21/0600Z 13.6N  28.2W    30 KTS
36HR VT     21/1800Z 13.8N  30.7W    35 KTS
48HR VT     22/0600Z 14.0N  33.0W    40 KTS
72HR VT     23/0600Z 14.5N  38.0W    50 KTS
 
 
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