Tropical Depression THIRTEEN

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TROPICAL DEPRESSION THIRTEEN DISCUSSION NUMBER   1
NWS NATIONAL HURRICANE CENTER MIAMI FL       AL132013
1100 AM EDT MON OCT 21 2013
 
THE CLOUD PATTERN OF THE LOW PRESSURE AREA WELL EAST-SOUTHEAST OF
BERMUDA HAS CONTINUED TO INCREASE IN ORGANIZATION THIS MORNING.
SATELLITE IMAGES SHOW A LONG CURVED BAND OVER THE EASTERN
SEMICIRCLE OF THE CIRCULATION...WITH A SMALL CLUSTER OF CONVECTION
ON THE EAST SIDE OF THE PARTIALLY EXPOSED LOW-LEVEL CENTER. AN
ASCAT PASS LAST NIGHT SUGGESTED THAT THE CENTER WAS BECOMING BETTER
DEFINED...AND THE INCREASE IN CONVECTIVE ORGANIZATION SUPPORTS
INITIATING ADVISORIES ON THIS SYSTEM. A DVORAK INTENSITY ESTIMATE
OF T2.0 FROM TAFB IS THE BASIS FOR THE INITIAL INTENSITY OF 30 KT.
 
THE INITIAL MOTION ESTIMATE IS 040/07.  THE DEPRESSION IS FORECAST
TO BE STEERED NORTHEASTWARD AROUND THE NORTHWEST SIDE OF A MID-
LEVEL RIDGE LOCATED NEAR 27N 47W DURING THE NEXT DAY OR SO.  AFTER
THAT TIME...THE CYCLONE SHOULD BECOME EMBEDDED IN NEARLY ZONAL
FLOW ALONG 30N AND TURN EAST-NORTHWARD UNTIL DISSIPATION.  THE NHC
TRACK FORECAST IS NEAR BUT JUST AHEAD OF THE MULTI-MODEL CONSENSUS
TO ACCOUNT FOR THE FASTER GFS SOLUTION.
 
THE DEPRESSION IS CURRENTLY IN DIFFLUENT FLOW ON THE NORTHEAST SIDE
OF AN UPPER-TROPOSPHERIC LOW NORTH OF PUERTO RICO. THE POSITION OF
THE TROPICAL CYCLONE RELATIVE TO THIS FEATURE SHOULD KEEP THE
WESTERLY SHEAR LOW ENOUGH DURING THE NEXT 24 TO 36 HOURS TO ALLOW
FOR SOME INTENSIFICATION WHILE THE DEPRESSION MOVES OVER WARM
WATERS.  BEYOND 36 HOURS...GLOBAL MODELS SHOW INCREASING WESTERLY
SHEAR THAT IS LIKELY TO CAUSE A DECOUPLING OF THE CYCLONE.
DISSIPATION IS FORECAST BY 96 HOURS...ALTHOUGH IT COULD OCCUR
SOONER. THE NHC INTENSITY FORECAST IS NEAR THE SHIPS/LGEM OUTPUT
THROUGH 36 HOURS AND THE NEAR THE MULTI-MODEL CONSENSUS FOR THE
REMAINDER OF THE FORECAST PERIOD.
   
FORECAST POSITIONS AND MAX WINDS
 
INIT  21/1500Z 28.0N  55.1W   30 KT  35 MPH
 12H  22/0000Z 28.9N  54.1W   35 KT  40 MPH
 24H  22/1200Z 29.6N  52.5W   40 KT  45 MPH
 36H  23/0000Z 30.1N  50.5W   40 KT  45 MPH
 48H  23/1200Z 30.4N  48.9W   35 KT  40 MPH
 72H  24/1200Z 31.4N  46.5W   30 KT  35 MPH
 96H  25/1200Z...DISSIPATED
 
$$
FORECASTER KIMBERLAIN
 
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