Official Discussion issued by the National Hurricane Center
ELEVEN (AL112009) DATA RELEASED: 11/4/2009 3:00:00 PM UTC
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Copy of official data TROPICAL DEPRESSION ELEVEN DISCUSSION NUMBER 1 NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL AL112009 1000 AM EST WED NOV 04 2009 THE AREA OF LOW PRESSURE IN THE SOUTHWESTERN CARIBBEAN SEA HAS DEVELOPED ENOUGH ORGANIZED THUNDERSTORM ACTIVITY TO NOW BE CONSIDERED A TROPICAL DEPRESSION. SATELLITE IMAGES SHOW THAT A NEW BURST OF THUNDERSTORMS IS OCCURRING NEAR THE CENTER WITH BANDING FEATURES BECOMING MORE DISTINGUISHED. TAFB/SAB DVORAK CLASSIFICATIONS WERE 2.0...30 KT...AT 1200 UTC...AND THAT INTENSITY WILL BE USED AS THE INITIAL WIND SPEED. IT WOULD NOT BE SURPRISING...HOWEVER...IF THIS SYSTEM WERE ALREADY A TROPICAL STORM DUE TO THE IMPROVING SATELLITE PRESENTATION. THE AIR FORCE RESERVE WILL BE IN THE AREA THIS AFTERNOON TO GIVE A BETTER ESTIMATE OF THE WINDS. THE INITIAL MOTION USED FOR THIS ADVISORY IS 315/7...THOUGH IT IS UNCERTAIN WHETHER THIS IS TRULY REPRESENTATIVE DUE TO THE CENTER REFORMATION THAT APPEARED TO OCCUR OVERNIGHT. STEERING CURRENTS ARE EXPECTED TO BE FAIRLY LIGHT DURING THE NEXT SEVERAL DAYS AS THE DEPRESSION IS CAUGHT BETWEEN A WEAK MID-LEVEL HIGH OVER THE NORTH-CENTRAL CARIBBEAN SEA AND A TROUGH OVER THE SOUTHWESTERN GULF OF MEXICO. ALTHOUGH THERE IS GENERAL AGREEMENT IN THE LARGE-SCALE PATTERN...THE MODELS ARE SHOWING A LARGE AMOUNT OF DIVERGENCE ON THE EXPECTED PATH OF THE DEPRESSION. MOST OF THE GUIDANCE SUGGEST THE SYSTEM WILL MOVE TO THE NORTHWEST THEN NORTH AROUND THE SOUTHWESTERN PERIPHERY OF THE CARIBBEAN RIDGE. HOWEVER...SOME OF THE RELIABLE GUIDANCE...SUCH AS THE ECMWF AND UKMET...SHOW THE SYSTEM MOVING CONSIDERABLY SLOWER WITH ONLY A NORTHWARD DRIFT. GIVEN THE UNCERTAINTY...THE NHC FORECAST IS NEAR BUT SLIGHTLY TO THE RIGHT OF THE MODEL CONSENSUS. ALTHOUGH THE DEPRESSION IS CURRENTLY IN A LIGHT SHEAR AND WARM WATER ENVIRONMENT...ITS PROXIMITY TO LAND AND UNCE |