Official Discussion issued by the National Hurricane Center
FIFTEEN (AL152008) DATA RELEASED: 10/13/2008 3:00:00 PM UTC
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Copy of official data 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 AN |