[NCEP Logo] HOME ARCHIVES FORECASTS IMAGERY ABOUT TPC RECONNAISSANCE

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TROPICAL DEPRESSION THIRTEEN DISCUSSION NUMBER   1
NATIONAL WEATHER SERVICE MIAMI FL
5 PM EDT SAT SEP 21 2002
 
THE AREA OF DISTURBED WEATHER IN THE TROPICAL ATLANTIC ASSOCIATED
WITH A TROPICAL WAVE HAS BECOME BETTER ORGANIZED WITH DVORAK
CLASSIFICATIONS OF 2.0 FROM BOTH TAFB AND SAB.  SHIP AND BUOY DATA
YESTERDAY ALSO HINTED THAT THERE WAS A BROAD LOW-LEVEL CIRCULATION
ASSOCIATED WITH THIS DISTURBANCE.  EVEN THOUGH CONVECTION HAS
WEAKENED THIS AFTERNOON...VISIBLE SATELLITE IMAGES SHOW DEVELOPING
CURVED BANDING FEATURES BENEATH A WELL-DEFINED UPPER-LEVEL
ANTICYCLONE.  THUS ADVISORIES ARE INITIATED ON TROPICAL DEPRESSION
THIRTEEN.

A FAVORABLE UPPER ENVIRONMENT IS EXPECTED TO CONTINUE OVER THE 
DEPRESSION AS IT MOVES WESTWARD OVER PROGRESSIVELY WARMER WATERS AT 
ABOUT 15 KNOTS.  SHIPS MODEL BRINGS THE DEPRESSION UP TO 91 KNOTS IN 
72 HOURS.  THE OFFICIAL FORECAST IS LITTLE MORE CONSERVATIVE UNTIL 
SOME SIGNALS OF SIGNIFICANT INTENSIFICATION ARE NOTED.  

THE SYSTEM IS SOUTH OF A MIDDLE-LEVEL RIDGE OVER THE CENTRAL 
ATLANTIC WHICH SHOULD PERSIST FOR THE MAJORITY OF THE FORECAST 
PERIOD.  HOWEVER...THIS RIDGE IS EXPECTED TO SLOWLY ERODE ON THE 
WESTERN SIDE... PARTIALLY DUE TO KYLE... AND COULD INDUCE A MORE A 
TRACK MORE TO THE NORTHWEST AFTER 48 HOURS.  FOR NOW THE FORECAST 
WILL STAY IN THE MIDDLE OF THE GUIDANCE ENVELOPE UNTIL ANY 
INTERACTIONS BETWEEN THE CYCLONES BECOME MORE CLEAR.
 
FORECASTER AVILA/BLAKE
 
FORECAST POSITIONS AND MAX WINDS
 
INITIAL     21/2100Z 10.4N  45.7W    30 KTS
12HR VT     22/0600Z 10.5N  48.0W    30 KTS
24HR VT     22/1800Z 11.0N  51.0W    30 KTS
36HR VT     23/0600Z 11.5N  53.5W    40 KTS
48HR VT     23/1800Z 12.5N  56.5W    50 KTS
72HR VT     24/1800Z 14.5N  61.0W    65 KTS
 
 
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