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NOAA NOAA United States Department of Commerce

Tropical Depression ELEVEN-E


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TROPICAL DEPRESSION ELEVEN-E DISCUSSION NUMBER   3
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
8 PM PDT WED SEP 03 2003
 
TROPICAL DEPRESSION ELEVEN-E HAS A LARGE CIRCULATION ELONGATED
NORTHWEST-SOUTHEAST WITH ABUNDANT CONVECTION IN A SOMEWHAT CURVED
BAND SOUTHWEST OF THE CENTER.  THE CENTER IS VERY DIFFICULT TO
LOCATE EVEN WITH VISIBLE IMAGERY...AND ALL THREE SATELLITE FIXES
ARE EAST OF THE PREVIOUS POSITION NEAR A BURST OF CONVECTION.  THIS
SUGGESTS THE CENTER COULD BE RE-FORMING.  GIVEN THE UNCERTAINTY...
THE INITIAL POSITION IS BASED PARTLY ON THE FIXES AND PARTLY ON
CONTINUITY FROM THE PREVIOUS ADVISORY.  SATELLITE INTENSITY
ESTIMATES ARE 30 KT FROM TAFB AND AFWA...AND 25 KT FROM SAB. THE
INITIAL INTENSITY REMAINS 30 KT. 

THE INITIAL MOTION IS A HIGHLY UNCERTAIN 295/6.  WATER VAPOR IMAGERY
AND MODEL ANALYSES INDICATE THAT THE CYCLONE IS SOUTH OF A MID/
UPPER-LEVEL RIDGE.  THE MODELS INDICATE THIS RIDGE SHOULD REMAIN IN
PLACE FOR 72 HR OR SO...THEN WEAKEN SOMEWHAT AS A STRONG WESTERLY
TROUGH MOVES TOWARD THE U. S. WEST COAST.  THIS SHOULD ALLOW THE
CYCLONE TO MOVE WEST-NORTHWESTWARD TO WESTWARD AT A FAIRLY SLOW
FORWARD SPEED.  THE TRACK FORECAST CALLS FOR A WEST-NORTHWESTWARD
MOTION THROUGH 48-72 HR...FOLLOWED BY A GRADUAL WESTWARD TURN AS
THE SYSTEM WEAKENS AND LOW-LEVEL STEERING BECOME PREDOMINANT. 
MODEL GUIDANCE GENERALLY AGREES WITH THIS SCENARIO...ALTHOUGH THE
BAM MODELS AND LBAR LIKELY TAKE THE SYSTEM TOO FAR NORTH INTO THE
LOW-LEVEL RIDGE AS THE CYCLONE WEAKENS.  THE FORECAST TRACK IS IN
BEST AGREEMENT WITH THE GFS...NOGAPS...AND NHC91.

THE DEPRESSION IS OVER SEA SURFACE TEMPERATURES OF 28C-29C...BUT THE
FORECAST TRACK TAKES THE CYCLONE OVER TEMPERATURES OF LESS THAN 24C
AFTER 72 HR.  THIS INDICATES A NARROW WINDOW FOR STRENGTHENING. 
SINCE THE CONVECTION IS STRONG AND THE SHEAR IS LIGHT TO
MODERATE...THE SYSTEM IS FORECAST TO REACH TROPICAL STORM STRENGTH
IN 12 HR OR LESS AND PEAK IN 36-48 HR.  GRADUAL WEAKENING SHOULD
OCCUR THEREAFTER.
 
FORECASTER BEVEN
 
FORECAST POSITIONS AND MAX WINDS
 
INITIAL      04/0300Z 19.6N 112.8W    30 KT
 12HR VT     04/1200Z 20.0N 113.6W    35 KT
 24HR VT     05/0000Z 20.6N 115.2W    40 KT
 36HR VT     05/1200Z 21.1N 117.1W    45 KT
 48HR VT     06/0000Z 21.5N 119.0W    45 KT
 72HR VT     07/0000Z 22.0N 122.5W    35 KT
 96HR VT     08/0000Z 22.5N 126.0W    25 KT...DISSIPATING
120HR VT     09/0000Z 22.5N 129.5W    20 KT...REMNANT LOW
 
 
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