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HURRICANE BONNIE DISCUSSION NUMBER  11
NATIONAL WEATHER SERVICE MIAMI FL
5 AM EDT SAT AUG 22 1998
 
ON THEIR LAST PASS THROUGH BONNIE NEAR 0530Z...THE HURRICANE HUNTERS
FOUND THAT A NEARLY COMPLETE EYEWALL HAD FORMED.  THEY ALSO REPORTED
A CENTRAL PRESSURE OF 987 MB WITH FLIGHT-LEVEL WINDS OF 76 KT.
SUSTAINED SURFACE WINDS ARE CURRENTLY ESTIMATED AT 65 KT.  THE
MOTION HAS EDGED OVER TO 300 DEGREES...STILL AT 15 KNOTS.
 
NOAA AIRCRAFT HAVE ONCE AGAIN PROVIDED THE NUMERICAL MODELS NUMEROUS
VERTICAL SOUNDINGS OF BONNIE/S ENVIRONMENT TO IMPROVE FORECASTS OF
TRACK AND INTENSITY.  THE RESULTING GUIDANCE AND OUR CONCERNS ARE
LITTLE CHANGED.  THE LARGE-SCALE MODELS SHOW A WEAKENING OF STEERING
CURRENTS DURING THE NEXT TWO DAYS...FOLLOWED BY THE APPROACH OF A
SHORT-WAVE TROUGH IN THE WESTERLIES WHICH COULD INDUCE A GREATER
NORTHWARD COMPONENT OF MOTION.  THE TRACK GUIDANCE IS SIMILAR TO 6
HOURS AGO SHOWING A GRADUAL TURN FROM WNW TO NW AND DECELERATION
THROUGH THE WEEKEND.  THE GFDL TRACK AGAIN FORMS THE LEFT EDGE OF
THE ENSEMBLE...BUT ALL THE GFDL 72-HOUR FORECAST POSITIONS FOR
BONNIE HAVE ENDED UP LEFT OF THE ACTUAL TRACK.  THE NHC FORECAST IS
TO THE RIGHT OF GFDL...NEAR LBAR WHICH HAS HAD LITTLE LATERAL
BIAS...AND CONSISTENT WITH OUR PREVIOUS TRACK.
 
THE GOVERNMENT OF THE BAHAMAS HAS ISSUED A HURRICANE WARNING FOR THE
CENTRAL BAHAMAS.

THE UPPER-LEVEL AND OCEAN ENVIRONMENT APPEAR FAVORABLE FOR
ADDITIONAL STRENGTHENING.

RAPPAPORT
 
FORECAST POSITIONS AND MAX WINDS
 
INITIAL     22/0900Z 22.1N  69.4W    65 KTS
12HR VT     22/1800Z 23.1N  71.3W    70 KTS
24HR VT     23/0600Z 24.1N  73.1W    80 KTS
36HR VT     23/1800Z 25.0N  74.2W    90 KTS
48HR VT     24/0600Z 26.0N  75.0W    95 KTS
72HR VT     25/0600Z 28.5N  75.5W   100 KTS
 
 
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