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TROPICAL DEPRESSION SIX DISCUSSION NUMBER   1
NATIONAL WEATHER SERVICE MIAMI FL
5 PM EDT SAT SEP 01 2001
 
A DRIFTING BUOY JUST WEST OF WHAT APPEARS TO BE A LOW LEVEL 
CIRCULATION CENTER ASSOCIATED WITH A TROPICAL WAVE REPORTED A 
NORTHWEST WIND AT 15 KNOTS AND A 1008.7 MB PRESSURE A COUPLE OF 
HOURS AGO.  ALSO SATELLITE IMAGERY SHOWS A MARKED INCREASE IN DEEP 
CONVECTION IN WHAT APPEARS TO BE A NORTH-SOUTH BANDING FEATURE.  
THESE ARE THE BASIS FOR UPGRADING THE TROPICAL WAVE NOW IN THE 
CENTRAL TROPICAL ATLANTIC TO A DEPRESSION.

THE INITIAL MOTION ESTIMATE IS 290/23.  THE 12Z AVIATION MODEL SHOWS 
A 500 MB RIDGE TO THE NORTH OF THE DEPRESSION FOR THE NEXT 72 HOURS.
THE VARIOUS GUIDANCE MODELS SHOW TRACKS BETWEEN WEST-NORTHWEST AND 
NORTH WITH THE GFDL THE LEFT-MOST TRACK.  THE OFFICIAL FORECAST 
FOLLOWS THE GFDL MODEL.  THE FORWARD SPEED DECREASES TO 13 KNOTS 
AFTER 48 HOURS. 

THE SHIPS MODEL BRINGS THE WIND SPEED TO 70 KNOTS IN 72 HOURS UNDER 
MODERATE VERTICAL SHEAR AND WARM SSTS.  OTHER GUIDANCE IS LESS 
AGGRESSIVE.  THE OFFICIAL FORECAST IS TO A CONSERVATIVE 55 KNOTS IN 
72 HOURS WHICH OF COURSE COULD BE TOO LITTLE.
 
FORECASTER LAWRENCE
  
FORECAST POSITIONS AND MAX WINDS
 
INITIAL     01/2100Z 12.9N  35.5W    30 KTS
12HR VT     02/0600Z 13.6N  38.1W    35 KTS
24HR VT     02/1800Z 14.3N  41.1W    40 KTS
36HR VT     03/0600Z 15.2N  44.3W    45 KTS
48HR VT     03/1800Z 16.2N  47.3W    50 KTS
72HR VT     04/1800Z 17.8N  52.5W    55 KTS
  
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