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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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