Hurricane ISABEL

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HURRICANE ISABEL DISCUSSION NUMBER  13
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
5 AM EDT TUE SEP 09 2003
 
06Z DVORAK SUBJECTIVE INTENSITY ESTIMATES WERE T NUMBER 6.0 OR 115
KNOT FROM ALL AGENCIES AND OBJECTIVE T NUMBERS WERE THE SAME. THE
WELL-DEFINED EYE AND CLOUD STRUCTURE REMAIN IMPRESSIVE.  THE
OFFICIAL INITIAL AND FORECAST INTENSITIES ARE IDENTICAL TO THE
PREVIOUS ADVISORY...TO 125 KNOTS IN 24 HOURS FOLLOWED BY SLOW
WEAKENING.  THE GLOBAL MODELS SHOW LITTLE CHANGE IN INTENSITY IN THE
NEXT 5 DAYS.  HOWEVER HURRICANES RARELY MAINTAIN SUCH A HIGH WIND
SPEED FOR FIVE DAYS AND THE SHIPS MODEL SHOWS WEAKENING AFTER 60
HOURS BECAUSE OF THIS FACTOR.  FABIANS COOL WAKE COULD ALSO BE A
NEGATIVE FACTOR.
 
THE INITIAL MOTION IS 300/12.  THE GFS SHOWS A STRONG SOUTHWARD
BUILDING OF THE SUBTROPICAL RIDGE AHEAD OF ISABEL AND THE TRACK
MODELS RESPOND BY SHOWING A TURN TOWARD THE SOUTHWEST DURING  DAY 1
THROUGH 3 FOLLOWED BY A SMALLER WESTWARD TURN ON DAY 4 OR 5.  THE
OFFICIAL FORECAST TRACK FOLLOWS A MODEL CONCENSUS AND IS SIMILAR TO
THE PREVIOUS ADVISORY FORECAST.
 
THE CENTER OF ISABEL IS FORECAST TO MOVE TO WITH ABOUT 200 MILES
NORTH OF THE NORTHEASTERNMOST ISLANDS OF THE CARIBBEAN ON DAYS 4
AND 5.  THE AVERAGE ERRORS OF 4 AND 5 DAY TRACK FORECASTS ARE MORE
THAN 200 MILES.
 
FORECASTER LAWRENCE
 
FORECAST POSITIONS AND MAX WINDS
 
INITIAL      09/0900Z 19.1N  45.7W   115 KT
 12HR VT     09/1800Z 19.8N  47.5W   120 KT
 24HR VT     10/0600Z 20.3N  49.4W   125 KT
 36HR VT     10/1800Z 20.3N  51.3W   120 KT
 48HR VT     11/0600Z 20.0N  53.3W   115 KT
 72HR VT     12/0600Z 19.5N  56.5W   110 KT
 96HR VT     13/0600Z 20.0N  59.5W   110 KT
120HR VT     14/0600Z 21.0N  63.0W   110 KT
 
 
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