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HURRICANE ISIDORE DISCUSSION NUMBER 21
NATIONAL WEATHER SERVICE MIAMI FL
5 AM EDT SAT SEP 21 2002
THE INITIAL MOTION ESTIMATE IS 290/5. THE MAJOR GUIDANCE MODELS...
AVN...GFDL...UKMET...AND NOGAPS....ARE ALL IN AGREEMENT ABOUT A SLOW
WEST TO WEST-SOUTHWESTWARD MOTION FOR THE NEXT 72 HOURS. FOR A
PREVIEW OF THE LONGER TERM...THESE MODELS ARE ALSO IN AGREEMENT
ABOUT ISIDORE GETTING PICKED UP BY THE A TROUGH IN THE WESTERLIES
AFTER 72 HOURS AND HEADING NORTHWARD. THE OFFICIAL FORECAST IS
ADJUSTED A LITTLE LEFT OF THE PREVIOUS TRACK GUIDANCE AND IS IN
CLOSE AGREEMENT WITH THE MODEL CONSENSUS.
THE PROXIMITY OF THE FORECAST TRACK TO THE YUCATAN PENINSULA
REQUIRES ISSUING A HURRICANE WARNING FOR ITS NORTH COAST.
THE CENTRAL SURFACE PRESSURE REMAINS 964 MB AND GPS DROPSONDES SHOW
THAT WINDS HAVE NOT INCREASED AND MIGHT BE A LITTLE LESS THAN THE 85
KNOT ADVISORY INITIAL WIND SPEED. HOWEVER...AN EYE IS APPEARING ON
THE LAST FEW INFRARED SATELLITE IMAGES. THE RECON AIRCRAFT REPORTS
CONCENTRIC EYE WALLS OF 15 AND 25 N MI DIAMETERS. VERTICAL SHEAR IS
LIGHT. SO ALL SYSTEMS ARE GO FOR SOME SERIOUS STRENGTHENING AND THE
FORECAST TO 115 KNOTS IN 72 HOURS IS THE SAME AS THE LAST ADVISORY.
FORECASTER LAWRENCE
FORECAST POSITIONS AND MAX WINDS
INITIAL 21/0900Z 22.4N 85.5W 85 KTS
12HR VT 21/1800Z 22.6N 86.5W 90 KTS
24HR VT 22/0600Z 22.3N 88.0W 100 KTS
36HR VT 22/1800Z 22.2N 89.1W 105 KTS
48HR VT 23/0600Z 21.8N 90.3W 110 KTS
72HR VT 24/0600Z 21.7N 91.5W 115 KTS
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