Tropical Depression EIGHT

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TROPICAL DEPRESSION EIGHT DISCUSSION NUMBER   6
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL   AL082007
500 PM EDT THU SEP 13 2007
 
CONVENTIONAL SATELLITE IMAGERY INDICATES A SMALLER WEAKER LOW
ROTATING ABOUT A MORE DOMINANT...BROAD...CIRCULATION TO THE
SOUTHEAST.  THE INITIAL POSITION WILL BE BASED ON A CENTROID
POSITION OF THE TWO CIRCULATION CENTERS.  THERE ARE NO CHANGES TO
THE DVORAK SATELLITE INTENSITY ESTIMATES FROM THIS MORNING...AND
THE INITIAL INTENSITY REMAINS AS 30 KT.     

THE OFFICIAL FORECAST INTENSITY REMAINS VIRTUALLY UNCHANGED FROM THE
PREVIOUS FORECAST...SUGGESTING A POSSIBILITY OF STRENGTHENING TO A
TROPICAL STORM DURING THE NEXT 12 HOURS.  AFTERWARD...THE INTENSITY
MODELS INDICATE VERY LITTLE STRENGTHENING THROUGH THE 72 HOUR
PERIOD...WITH A WEAKENING THROUGH THE REMAINDER OF THE PERIOD AS
UPPER LEVEL WESTERLIES ARE EXPECTED TO SPREAD FROM THE EASTERN
CARIBBEAN OVER THE ADJACENT ATLANTIC WATERS.
 
INITIAL MOTION IS ESTIMATED AT 290/5...A LITTLE TO THE RIGHT OF THE
PREVIOUS PACKAGE.  THE CYCLONE SHOULD GRADUALLY CONTINUE ON A
GENERAL WEST-NORTHWESTWARD MOTION WITHIN WEAK STEERING FLOW OF A
MID- TROPOSPHERIC RIDGE TO THE NORTH THROUGH THE FORECAST PERIOD. 
THE DYNAMICAL MODELS ARE IN MORE AGREEMENT THAN THIS MORNING...WITH
THE 12Z ECMWF NOW SUGGESTING A MOTION SIMILAR TO THE OTHER MODELS. 
THE NOGAPS...HOWEVER...SHOWS THE MOST VERTICAL DEPTH WHICH APPEARS
TO BE INFLUENCING A DRAMATIC TURN TO THE RIGHT TOWARD A
RETROGRADING UPPER LEVEL TROUGH SITUATED TO THE NORTHEAST OF THE
DEPRESSION.  THE OFFICIAL FORECAST IS SIMILAR TO THE PREVIOUS
FORECAST...WITH A SLIGHT ADJUSTMENT TO THE RIGHT...AND AGREES WITH
A BLEND OF ALL THE AVAILABLE DYNAMICAL GUIDANCE WITH THE EXCEPTION
OF THE NOGAPS. 
 
FORECAST POSITIONS AND MAX WINDS
 
INITIAL      13/2100Z 14.2N  48.4W    30 KT
 12HR VT     14/0600Z 14.5N  49.2W    35 KT
 24HR VT     14/1800Z 15.0N  50.2W    35 KT
 36HR VT     15/0600Z 15.5N  51.4W    35 KT
 48HR VT     15/1800Z 15.9N  52.5W    40 KT
 72HR VT     16/1800Z 17.0N  55.4W    40 KT
 96HR VT     17/1800Z 18.0N  58.0W    35 KT
120HR VT     18/1800Z 19.1N  60.5W    30 KT
 
$$
FORECASTER ROBERTS/BEVEN
 
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