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TROPICAL STORM CHANTAL DISCUSSION NUMBER  10
NATIONAL WEATHER SERVICE MIAMI FL
11 PM EDT FRI AUG 17 2001
 
THE INITIAL MOTION ESTIMATE IS 280/20 OVER THE PAST 12 HOURS... 
POSSIBLY A LITTLE SLOWER OVER THE PAST 6 HOURS.  THE 500-MB TROUGH 
OVER THE EASTERN U.S. IS FORECAST TO AMPLIFY A LITLE OVER THE NEXT 3 
DAYS.  THIS SHOULD WEAKEN THE RIDGE NORTH OF CHANTAL WEST OF ABOUT 
80W CAUSING CHANTAL TO GRADUALLY SLOW TO LESS THAN 15 KNOTS BY
48 HOURS.  THE FORECAST TRACK IS SIMILAR TO THE PREVIOUS ADVISORY
AND IS A BLEND OF THE AVIATION...GFDL AND UKMET MODELS.
 
AN AIR FORCE RECON AIRCRAFT IN THE STORM REPORTED A MAXIMUM WIND OF 
58 KNOTS AT 1500 FT NORTH OF THE CENTER AND 1004 MB CENTRAL 
PRESSURE.  THE INITIAL WIND SPEED IS INCREASED TO 45 KNOTS BASED ON 
THIS RECON WIND OBSERVATION.  RECENT SATELLITE IMAGERY SHOWS WHAT 
MAY BE THE BEGINNING OF A STRENGTHENING PHASE AS THE CONVECTION HAS 
BECOME MORE CONCENTRATED NEAR THE CENTER AND A BANDING FEATURE AND 
UPPER LEVEL OUTFLOW LOOK IMPRESSIVE.  IN CONTRAST THE AIRCRAFT 
REPORTED THAT THE CIRCULATION AT 15OO FT IS NOT VERY WELL DEFINED.  
WITH GREAT UNCERTAINTY...THE FORECAST IS FOR STRENGTHENING TO A
HURRICANE IN 24 HOURS AND TO 80 KNOTS IN 72 HOURS.  THIS IS A LITTLE 
MORE AGGRESSIVE THAN THE SHIPS AND GFLD GUIDANCE...AND A LOT MORE 
AGGRESSIVE THAN THE UKMET MODEL WHICH DOES NOT INDICATE SIGNIFICANT 
STRENGTHENING FOR THE NEXT 3 DAYS.
 
THE GOVERNMENT OF JAMAICA HAS DECIDED TO WAIT A LITTLE LONGER BEFORE
ISSUING A TROPICAL STORM OR HURRICANE WARNING.
 
FORECASTER LAWRENCE
 
FORECAST POSITIONS AND MAX WINDS
 
INITIAL     18/0300Z 14.6N  69.2W    45 KTS
12HR VT     18/1200Z 15.3N  72.2W    55 KTS
24HR VT     19/0000Z 16.2N  75.5W    65 KTS
36HR VT     19/1200Z 17.1N  78.4W    75 KTS
48HR VT     20/0000Z 18.0N  81.3W    75 KTS
72HR VT     21/0000Z 19.5N  86.5W    80 KTS
  
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