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TROPICAL STORM CHANTAL DISCUSSION NUMBER 23
NATIONAL WEATHER SERVICE MIAMI FL
5 AM EDT TUE AUG 21 2001
SURFACE OBSERVATIONS FROM CHETUMAL AND BELIZE CITY...ALONG WITH
RADAR REPORTS FROM BELIZE...INDICATE THAT CHANTAL EITHER STALLED OR
DEVELOPED A NEW CENTER FURTHER SOUTH AND EAST OF THE PREVIOUS
ADVISORY POSITION. IN FACT...THE 08Z RADAR DATA INDICATED AN
EYEWALL TRYING TO CLOSE OFF BETWEEN SAN PEDRO AND COROZAL.
SATELLITE DATA ALSO INDICATES THAT DEEP CONVECTION HAS DEVELOPED
OVER THIS NEW RADAR CENTER...SO THE INITIAL POSITION WAS ADJUSTED
BACK TO THE EAST. THE INITIAL INTENSITY WAS DECREASED SLIGHTLY
BASED ON WIND REPORTS RECEIVED FROM NORTHERN BELIZE AND NEAR
CHETUMAL.
THE INITIAL MOTION ESTIMATE IS 290/03 BASED ON THE LAST 3 RADAR
POSITIONS. DESPITE THE NEARLY STATIONARY MOTION THIS MORNING...
THERE REMAINS LITTLE CHANGE TO THE TRACK FORECAST PHILOSOPHY. THE
AVN AND UKMET GLOBAL MODELS MAINTAIN THE MID-LEVEL RIDGE TO THE
NORTH OF CHANTAL THROUGHOUT THE FORECAST PERIOD. THE LATEST
FORECAST TRACK IS JUST AND UPDATE OF THE PREVIOUS FORECAST...ALBEIT
A LITTLE SLOWER TO TAKE INTO ACCOUNT THE RELOCATION OF THE CENTER.
IT APPEARS THAT ALL OF THE MODELS UNDERESTIMATED THE STRENGTH OF THE
HIGH AMPLITUDE TROUGH THAT EXTENDS FROM THE NORTHEAST U.S. SOUTHWEST
INTO THE BAY OF CAMPECHE. SOME ERRATIC MOTION MAY CONTINUE THIS
MORNING...BUT A RESUMPTION OF A WEST-NORTHWEST TRACK APPEARS TO BE
IN ORDER GIVEN THE STRENGTH OF THE LOW-LEVEL RIDGE OVER THE GULF OF
MEXICO.
ONLY SLOW STRENGTHENING IS FORECAST ONCE CHANTAL REACHES THE GULF OF
MEXICO...ESPECIALLY IF CHANTAL REMAINS OVER THE YUCATAN LONGER THE
OFFICIAL IS INDICATING.
NOTE...A SPECIAL THANKS IS IN ORDER FOR THE BELIZE MET OFFICE FOR
PROVIDING SUCH TIMELY AND ACCURATE RADAR REPORTS.
FORECASTER STEWART
FORECAST POSITIONS AND MAX WINDS
INITIAL 21/0900Z 18.3N 88.3W 55 KTS
12HR VT 21/1800Z 18.7N 89.3W 35 KTS...INLAND
24HR VT 22/0600Z 19.1N 90.2W 35 KTS...INLAND
36HR VT 22/1800Z 19.4N 91.2W 45 KTS
48HR VT 23/0600Z 19.7N 92.3W 55 KTS
72HR VT 24/0600Z 20.0N 94.0W 65 KTS
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