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HURRICANE GERT DISCUSSION NUMBER   9
NATIONAL WEATHER SERVICE MIAMI FL
11 AM EDT MON SEP 13 1999

SATELLITE IMAGES SHOW THAT GERT CONTINUES TO BECOME BETTER ORGANIZED
WITH HOOKING BANDS AND A WELL ESTABLISHED OUTFLOW. T-NUMBERS FROM
TAFB AND SAB ARE 4.0 ON THE DVORAK SCALE.  THEREFORE...GERT IS BEING
UPGRADED TO HURRICANE STATUS AT THIS TIME...THE FIFTH HURRICANE OF
THE SEASON.

SHIPS...BRINGS GERT TO 96 KNOTS WHILE THE GFDL LOWER THE PRESSURE TO
NEAR 940 MB BY 72 HOURS. THESE MODELS HAVE BEEN PERFORMING VERY WELL
IN FORECASTING INTENSITY TRENDS SO FAR THIS YEAR.  THEREFORE...THE
OFFICIAL FORECAST BRINGS GERT TO 100 KNOTS IN 3 DAYS.   

GERT IS MOVING ABOUT 280/17.  THERE IS A STRONG SUBTROPICAL RIDGE TO
THE NORTH OF THE HURRICANE WHICH IS FORECAST TO PERSIST AND EVEN
STRENGTHEN. THEREFORE A CONTINUED WESTWARD TRACK IS EXPECTED THROUGH
72 HOURS. THIS IS CONSISTENT WITH TRACK MODELS..INCLUDING THE GFDL
WHICH MOVES GERT SOUTH OF DUE WEST.  LONGER RANGE MODELS PUT THE
HURRICANE VERY NEAR OR OVER THE NORTHERN LEEWARD ISLANDS IN ABOUT 4
DAYS.  HOWEVER...THESE FORECASTS ARE HIGHLY UNCERTAIN.

AVILA
 
FORECAST POSITIONS AND MAX WINDS
 
INITIAL     13/1500Z 16.1N  40.1W    65 KTS
12HR VT     14/0000Z 16.5N  42.7W    70 KTS
24HR VT     14/1200Z 16.8N  45.5W    75 KTS
36HR VT     15/0000Z 17.0N  48.5W    85 KTS
48HR VT     15/1200Z 17.0N  51.5W    95 KTS
72HR VT     16/1200Z 17.0N  57.5W   100 KTS
 
 
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