Tropical Depression SIX-E

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TROPICAL DEPRESSION SIX-E SPECIAL DISCUSSION NUMBER   1
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL   EP062008
1000 PM PDT FRI JUL 11 2008

CONVENTIONAL SATELLITE IMAGERY AND A NUMBER OF MICROWAVE OVERPASSES
SUGGEST THAT THE AREA OF LOW PRESSURE SITUATED A FEW HUNDRED MILES
SOUTH OF THE GULF OF TEHUANTEPEC HAS ACQUIRED SUFFICIENT ORGANIZED
CONVECTION TO BE CLASSIFIED AS A TROPICAL DEPRESSION.  A 0015Z
QUIKSCAT PASS INDICATED 30 KT WINDS WITHING THE DEVELOPING SPIRAL
BAND OVER THE EASTERN PORTION OF THE SYSTEM.  ADDITIONALLY...DVORAK
T-NUMBERS FROM TAFB AND SAB ARE 35 AND 30 KT RESPECTIVELY.  THE
INITIAL INTENSITY IS SET AT 30 KT FOR THIS ADVISORY.  DYNAMICAL
MODELS AND THE SHIPS SHOW THE EASTERLY SHEAR DECREASING AS THE
CYCLONE TRAVERSES OVER WARM WATERS DURING THE NEXT 3 OF DAYS.
THROUGH THE REMAINING PORTION OF THE FORECAST...THE SYSTEM IS
EXPECTED TO MOVE OVER COOLER WATERS.  THEREFORE...THE INTENSITY
FORECAST CALLS FOR GRADUAL STRENGTHENING THROUGH THE 72 HOUR
PERIOD...THEN HOLDING AT 60 KT THROUGH DAY 5.

INITIAL MOTION IS ESTIMATED AT 300/14...WITHIN THE LOW TO MID LAYER
FLOW SOUTH OF A RIDGE EXTENDING FROM THE GULF OF MEXICO WESTWARD
OVER WESTERN MEXICO.  LARGE-SCALE AND HURRICANE MODELS SUGGEST THAT
THE RIDGE WILL BUILD FURTHER WEST OVER BAJA CALIFORNIA AS AN UPPER
TROUGH OVER THE AREA WEAKENS AND DRIFTS NORTHWEST.  THIS SYNOPTIC
STEERING PATTERN SHOULD CAUSE THE DEPRESSION TO MOVE IN A GENERAL
WEST-NORTHWESTWARD MOTION THROUGH THE ENTIRE FORECAST. THE FORECAST
TRACK IS BASED ON A BLEND OF THE AVAILABLE DYNAMICAL MODELS AND THE
GFS BAMM MID-LAYER MEAN TRAJECTORY MODEL.       


FORECAST POSITIONS AND MAX WINDS
 
INITIAL      12/0500Z 12.3N  96.3W    30 KT
 12HR VT     12/1200Z 13.1N  97.7W    35 KT
 24HR VT     13/0000Z 14.0N 100.1W    40 KT
 36HR VT     13/1200Z 14.8N 102.4W    45 KT
 48HR VT     14/0000Z 15.6N 104.6W    50 KT
 72HR VT     15/0000Z 17.0N 108.5W    60 KT
 96HR VT     16/0000Z 18.0N 112.0W    60 KT
120HR VT     17/0000Z 18.5N 116.0W    60 KT
 
$$
FORECASTER ROBERTS/KNABB
 
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