Tropical Depression FOURTEEN

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TROPICAL DEPRESSION FOURTEEN DISCUSSION NUMBER   3
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL   AL142007
1100 PM EDT FRI SEP 28 2007
 
CONVECTION ASSOCIATED WITH TROPICAL DEPRESSION FOURTEEN HAS
INCREASED DURING THE EVENING...BUT IS BEING DISPLACED EAST OF THE
CENTER BY WESTERLY VERTICAL WIND SHEAR.  AN EARLIER QUIKSCAT
OVERPASS DID NOT SHOW ANY WINDS HIGHER THAN 25 KT OUTSIDE THE
CONVECTION...WITH HIGHER SPEEDS IN THE CONVECTION LOOKING SUSPECT
DUE TO RAIN CONTAMINATION.  THE INITIAL INTENSITY REMAINS 30 KT
BASED MAINLY ON PERSISTENCE FROM THE PREVIOUS ADVISORY.

THE INITIAL MOTION IS A SOMEWHAT UNCERTAIN 280/4.  THE DEPRESSION IS
ON THE SOUTH SIDE OF A WEAK LOW/MID-LEVEL RIDGE...WHICH THE
LARGE-SCALE MODELS SUGGEST WILL WEAKEN AS A MID/UPPER-LEVEL TROUGH
APPROACHES FROM THE NORTH.  THIS EVOLUTION IS FORECAST TO STEER THE
DEPRESSION WEST-NORTHWESTWARD AND THEN NORTHWESTWARD.  MOST OF THE
TRACK GUIDANCE AGREES WITH THIS SCENARIO...ALTHOUGH THE ECMWF
MODELS KEEPS A STRONGER RIDGE AND IN CONSEQUENCE SHOWS A MORE
WESTERLY TRACK.  THE NEW FORECAST TRACK IS SHIFTED A LITTLE TO THE
LEFT OF THE PREVIOUS TRACK AND IS IN THE MIDDLE OF THE ENVELOPE OF
GUIDANCE.

THE LARGE-SCALE MODELS FORECAST UPPER-LEVEL WINDS TO BE MARGINALLY
FAVORABLE FOR STRENGTHENING ALONG THE FORECAST TRACK FOR PERHAPS 24
HR.  AFTER THAT...THE CYCLONE SHOULD ENCOUNTER SLIGHTLY COOLER
WATERS AND INCREASING SHEAR.  THE INTENSITY FORECAST THUS CALLS FOR
SLIGHT STRENGTHENING IN THE FIRST 12-24 HR...FOLLOWED BY WEAKENING
TO A DEPRESSION BY 36 HR AND TO A REMNANT LOW BY 96 HR.  NONE OF
THE DYNAMICAL MODELS FORECAST THE SYSTEM TO EXIST AS A CLOSED
CIRCULATION BY 120 HR...SO THE NEW INTENSITY FORECAST CALLS FOR
DISSIPATION BY THAT TIME.
  
FORECAST POSITIONS AND MAX WINDS
 
INITIAL      29/0300Z 14.2N  27.5W    30 KT
 12HR VT     29/1200Z 14.5N  28.5W    35 KT
 24HR VT     30/0000Z 15.1N  30.0W    35 KT
 36HR VT     30/1200Z 15.8N  31.8W    30 KT
 48HR VT     01/0000Z 16.8N  33.2W    30 KT
 72HR VT     02/0000Z 18.5N  35.0W    25 KT...DISSIPATING
 96HR VT     03/0000Z 20.5N  37.0W    20 KT...REMNANT LOW
120HR VT     04/0000Z...DISSIPATED
 
$$
FORECASTER BEVEN
 
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