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TROPICAL STORM CHANTAL DISCUSSION NUMBER 5
NATIONAL WEATHER SERVICE MIAMI FL
11 AM EDT THU AUG 16 2001
CHANTAL IS MOVING RAPIDLY WESTWARD ABOUT 20 TO 25 KNOTS AROUND THE
PERIPHERY OF A STRONG MID-LEVEL RIDGE. MOST OF THE AVAILABLE MODELS
INDICATE THAT THIS RIDGE WILL PERSIST...FORCING CHANTAL ON A GENERAL
WEST-TO WEST-NORTHWEST TRACK THROUGH THE CARIBBEAN SEA. A DECREASE
IN FORWARD SPEED IS EXPECTED BY THE END OF THE FORECAST PERIOD.
THE OVERALL CLOUD PATTERN HAS IMPROVED SINCE YESTERDAY WITH BANDING
FEATURES AND AN EXCELLENT OUTFLOW. HOWEVER...CONVECTION IS STILL
SOMEWHAT WEAK NEAR THE CENTER. INITIAL INTENSITY IS 35 KNOTS AND A
THERE WILL BE BETTER ESTIMATE OF THE MAXIMUM WINDS WHEN THE
RECONNAISSANCE PLANE CHECKS THE AREA LATER TODAY. THERE IS AN
UPPER-LEVEL ANTICYCLONE OVER THE SYSTEM THAT GLOBAL MODELS KEEP WITH
THE TROPICAL CYCLONE. DESPITE THIS APPARENTLY FAVORABLE UPPER-LEVEL
PATTERN...GLOBAL MODELS WEAKEN THE SYSTEM. THE GFDL...WHICH
PREVIOUSLY MADE CHANTAL A HURRICANE IS NOW ALSO WEAKENING IT. WITH
SUCH FAVORABLE ENVIRONMENT... IT IS REASONABLE TO INDICATE
STRENGTHENING IN THE OFFICIAL FORECAST. IN THE SHORT TERM...THE
SHIPS RAPID INTENSIFICATION INDEX SUGGESTS THAT CHANTAL COULD
QUICKLY REACH HURRICANE STRENGTH.
NOTE...WITH THE EXCEPTION OF THE FORWARD SPEED OF THE STORM...ALL
INGREDIENTS APPEAR TO BE PRESENT AT THIS TIME TO HAVE A POTENTIALLY
DANGEROUS HURRICANE MOVING THROUGH THE WESTERN CARIBBEAN SEA. ALL
INTERESTS IN THE AREA SHOULD MONITOR THE PROGRESS OF CHANTAL DURING
THE NEXT FEW DAYS.
FORECASTER AVILA
FORECAST POSITIONS AND MAX WINDS
INITIAL 16/1500Z 13.1N 55.3W 35 KTS
12HR VT 17/0000Z 13.5N 59.0W 45 KTS
24HR VT 17/1200Z 14.5N 64.0W 55 KTS
36HR VT 18/0000Z 15.0N 68.0W 65 KTS
48HR VT 18/1200Z 16.0N 72.0W 75 KTS
72HR VT 19/1200Z 17.5N 77.0W 80 KTS
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