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Tropical Depression NINE-E


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TROPICAL DEPRESSION NINE-E DISCUSSION NUMBER   6
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL   EP092009
800 PM PDT MON AUG 10 2009

THE CENTER OF THE DEPRESSION REMAINS EXPOSED TO THE WEST OF THE DEEP
CONVECTION...DUE TO WESTERLY SHEAR.  MORE RECENTLY THE CONVECTION
HAS DEVELOPED A LITTLE CLOSER TO THE CENTER AND IS EXHIBITING
SLIGHTLY MORE CURVATURE.  HOWEVER...THE DVORAK DATA T-NUMBERS FROM
BOTH AGENCIES ARE 2.0...WHICH SUPPORT MAINTAINING THE INTENSITY AT
30 KT.  THE DEPRESSION IS CURRENTLY PASSING NEAR THE BASE OF AN
UPPER-LEVEL TROUGH WHICH HAS BEEN RESPONSIBLE FOR THE SHEAR.  THE
GLOBAL MODELS SUGGEST THAT ONCE THE CYCLONE MOVES WEST OF THE
TROUGH AXIS...THE UPPER-LEVEL WINDS SHOULD DECREASE 
AND TURN NORTHEASTERLY.  THIS IS EXPECTED TO RESULT IN A 
RELAXATION OF THE SHEAR IN ABOUT 24-36 HOURS.  AFTER THAT TIME...
THE STATISTICAL GUIDANCE PREDICTS MODEST STRENGTHENING THROUGH 72
HOURS.  ON THE OTHER HAND...THE DYNAMICAL MODELS FORECAST NO
STRENGTHENING AND MANY SHOW DISSIPATION WITHIN A COUPLE OF DAYS. 
THE FUTURE OF DEPRESSION APPEARS TO BE HIGHLY DEPENDANT ON ITS
SURVIVAL DURING THE NEXT DAY OR SO.  GIVEN THIS UNCERTAINTY...THE
OFFICIAL FORECAST WILL FOLLOW THE PREVIOUS ADVISORY AND THE
DYNAMICAL GUIDANCE...WHICH KEEP THE CYCLONE BELOW TROPICAL STORM
STRENGTH.
 
THE DEPRESSION IS MOVING WESTWARD AT ABOUT 10 KT.  THE TRACK
GUIDANCE IS IN GOOD AGREEMENT ON A GENERAL WESTWARD MOTION DURING
THE NEXT 2-3 DAYS...THEREAFTER THE MODELS WHICH WEAKEN THE CYCLONE
TURN IT WEST-SOUTHWESTWARD.  THE OFFICIAL FORECAST ASSUMES THAT THE
CYCLONE WILL REMAIN A SHALLOW SYSTEM AND NOT GAIN MUCH LATITUDE. 
THE NEW NHC TRACK FORECAST IS AN UPDATE OF THE PREVIOUS TRACK AND
REMAINS CLOSE TO THE FORWARD SPEED OF THE MODEL CONSENSUS.
 
FORECAST POSITIONS AND MAX WINDS
 
INITIAL      11/0300Z 15.1N 125.4W    30 KT
 12HR VT     11/1200Z 15.3N 126.9W    30 KT
 24HR VT     12/0000Z 15.5N 128.7W    30 KT
 36HR VT     12/1200Z 15.6N 130.6W    30 KT
 48HR VT     13/0000Z 15.6N 132.5W    30 KT
 72HR VT     14/0000Z 15.6N 136.3W    25 KT
 96HR VT     15/0000Z 15.5N 140.5W    20 KT...REMNANT LOW
120HR VT     16/0000Z...DISSIPATED
 
$$
FORECASTER BROWN
 
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