Tropical Depression FIFTEEN-E

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TROPICAL DEPRESSION FIFTEEN-E DISCUSSION NUMBER   3
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
2 AM PDT TUE OCT 12 2004
 
INFRARED SATELLITE IMAGERY AND RADAR DISPLAYS FROM ACAPULCO MEXICO
SUGGEST THAT CONVECTION ASSOCIATED WITH TROPICAL DEPRESSION 15-E
CURRENTLY COVERS ONLY A SMALL AREA NEAR AND NORTHWEST OF THE
CENTER.  THIS IS SUPPORTED BY A 0438Z AMSU OVERPASS...WHICH SHOWED
THE CENTER EXPOSED SOUTHEAST OF THE CONVECTION.  SATELLITE
INTENSITY ESTIMATES ARE 35 KT FROM TAFB AND SAB...AND 30 KT FROM
AFWA.  SINCE THE OVERALL COVERAGE AND INTENSITY OF THE CONVECTION
IS LESS THAN 6 HR AGO...THE SYSTEM REMAINS A 30 KT DEPRESSION FOR
THIS ADVISORY.

THE INITIAL MOTION IS A SOMEWHAT UNCERTAIN 295/6.  WATER VAPOR
IMAGERY SHOWS A MID/UPPER-LEVEL ANTICYCLONE OVER THE YUCATAN
PENINSULA WITH A RIDGE EXTENDING TO 17N100W...WHILE A LARGE
MID/UPPER-LEVEL TROUGH COVERS THE TROPICAL PACIFIC N OF 15N FROM
105W-130W.  DYNAMICAL MODELS SUGGEST THE TROUGH WILL MOVE
WESTWARD...WHILE A RIDGE GRADUALLY BUILDS NORTH OF THE TROPICAL
CYCLONE.  THIS SHOULD CAUSE THE DEPRESSION TO MOVE GENERALLY
WEST-NORTHWESTWARD AND WESTWARD...PARALLEL TO THE MEXICAN COAST FOR
THE FIRST 36-48 HR AND THEN AWAY FROM THE COAST.  THE GFS AND UKMET
BOTH CALL FOR A WEST-NORTHWESTWARD MOTION CLOSE TO THE COAST...AS
DOES THE MODEL CONSENSUS.  HOWEVER...THERE IS NO 00Z NOGAPS RUN
AVAILABLE...AND ITS 18Z RUN CALLED FOR A MORE WESTWARD MOTION AWAY
FROM THE COAST.  WITHOUT SEEING THE NEW NOGAPS...THERE IS A
RELUCTANCE TO SHIFT THE FORECAST TRACK TOO FAR TO THE RIGHT. 
THUS...THE NEW FORECAST IS SHIFTED SOMEWHAT TO THE RIGHT OF THE
PREVIOUS TRACK...BUT NOT AS FAR AS THE GFS AND UKMET.  IT SHOULD BE
NOTED THAT IF THE GFS AND UKMET VERIFY...THE CENTER WOULD COME
CLOSE ENOUGH TO THE COAST TO REQUIRE WATCHES OR WARNINGS LATER
TODAY...AND TO BRING LOCALLY HEAVY RAINS ONSHORE.

THE CYCLONE IS NEAR TROPICAL STORM STRENGTH.  HOWEVER...IT IS
CURRENTLY EXPERIENCING SOUTHEASTERLY TO SOUTHERLY SHEAR...AND IT IS
NOT YET DEVELOPING ITS OWN OUTFLOW PATTERN.  THE DYNAMICAL MODELS
SUGGEST THAT AN ANTICYCLONE SHOULD BUILD OVER THE SYSTEM FROM 24-72
HR...WHICH WOULD ALLOW STRENGTHENING.  THE INTENSITY FORECAST THUS
CALLS FOR GRADUAL STRENGTHENING DURING THE FIRST 12-24 HR AND
FASTER STRENGTHENING THEREAFTER.  THE SHIPS MODEL SUGGESTS THAT
SHEAR WILL INCREASE AFTER 72 HR...AND THE INTENSITY FORECAST CALLS
FOR SLIGHT WEAKENING IN AGREEMENT WITH THAT.  AS NOTED EARLIER...
TROPICAL DEPRESSION 15-E IS A SMALL CYCLONE AND COULD SHOW RAPID
FLUCTUATIONS IN STRENGTH BOTH UP AND DOWN.
 
FORECASTER BEVEN
 
FORECAST POSITIONS AND MAX WINDS
 
INITIAL      12/0900Z 15.0N  98.0W    30 KT
 12HR VT     12/1800Z 15.2N  98.7W    35 KT
 24HR VT     13/0600Z 15.5N 100.0W    45 KT
 36HR VT     13/1800Z 15.6N 101.2W    55 KT
 48HR VT     14/0600Z 15.8N 102.7W    65 KT
 72HR VT     15/0600Z 16.0N 105.0W    70 KT
 96HR VT     16/0600Z 16.0N 107.5W    70 KT
120HR VT     17/0600Z 17.0N 110.5W    65 KT
 
 
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