Tropical Depression FIFTEEN

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TROPICAL DEPRESSION FIFTEEN DISCUSSION NUMBER   1
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL   AL152008
1100 AM EDT MON OCT 13 2008
 
THE AREA OF LOW PRESSURE OVER THE EASTERN CARIBBEAN SEA HAS
DEVELOPED ENOUGH CIRCULATION AND DEEP CONVECTION TO BE CLASSIFIED
AS A TROPICAL DEPRESSION. NORMALLY...I WOULD WAIT FOR THE
RECONNAISSANCE PLANE WHICH IN FACT IS SCHEDULE FOR THIS AFTERNOON TO
START ADVISORIES...BUT IN THIS CASE...THERE ARE DATA SUPPORTING THE
PRESENCE OF A TROPICAL DEPRESSION.  THE CYCLONIC CIRCULATION CAN BE
DEPICTED ON THE CURACAO RADAR...SURFACE OBSERVATIONS..CLOUD WIND
VECTORS AND ON THE LATEST QUIKSCAT PASS THIS MORNING. INITIAL
INTENSITY IS 30 KNOTS BASED ON DVORAK CLASSIFICATIONS AND QUIKSCAT.
THE DEPRESSION IS NOT EMBEDDED IN THE BEST ENVIRONMENT FOR
STRENGTHENING SINCE THERE IS SOUTHWESTERLY SHEAR...BUT IS FAVORABLE
ENOUGH TO ALLOW THE CYCLONE TO REACH TROPICAL STORM INTENSITY IN 12
TO 24 HOURS. THEREAFTER...THE SHEAR IS FORECAST TO INCREASE SOME
MAKING THE INTENSITY FORECAST HIGHLY UNCERTAIN. AT THIS TIME...THE
OFFICIAL FORECAST IS A BLEND OF THE STATISTICAL MODEL SHIPS AND THE
DYNAMICAL MODELS GFDL AND HWRF. IN FACT...THE GFDL AND HWRF
FORECAST THE DEPRESSION TO BE A HURRICANE AS IT MOVES NEAR
PUERTO RICO.
  
THE DEPRESSION IS EMBEDDED WITHIN LIGHT STEERING CURRENTS AND IS
DRIFTING NORTHWESTWARD. SINCE NO CHANGE IN STEERING IS EXPECTED FOR
A DAY OR TWO...NO SIGNIFICANT MOTION IS ANTICIPATED DURING THAT
PERIOD. THEREAFTER...GLOBAL MODELS DEVELOP A LARGE AND STRONG MID-
LATITUDE TROUGH OVER THE WESTERN ATLANTIC. THE CYCLONE IS EXPECTED
TO BECOME EMBEDDED WITHIN THE SOUTHWESTERLY FLOW AHEAD OF THIS
TROUGH AND RECURVE. THIS TRACK SHOULD BRING THE CYCLONE VERY CLOSE
TO PUERTO RICO BETWEEN 48 AND 72 HOURS AND OVER THE OPEN ATLANTIC
THEREAFTER. THIS TRACK IS VERY CLOSE TO THE MODEL CONSENSUS AND
ALSO IS HEAVILY BIASED TOWARD THE GFDL AND HWRF MODELS.
 
FORECAST POSITIONS AND MAX WINDS
 
INITIAL      13/1500Z 14.8N  69.6W    30 KT
 12HR VT     14/0000Z 15.1N  70.0W    35 KT
 24HR VT     14/1200Z 15.5N  70.0W    45 KT
 36HR VT     15/0000Z 16.0N  69.0W    50 KT
 48HR VT     15/1200Z 17.0N  67.5W    55 KT
 72HR VT     16/1200Z 20.0N  63.5W    65 KT
 96HR VT     17/1200Z 24.0N  59.5W    65 KT
120HR VT     18/1200Z 30.0N  55.0W    65 KT
 
$$
FORECASTER AVILA
 
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