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HURRICANE BONNIE DISCUSSION NUMBER  16
NATIONAL WEATHER SERVICE MIAMI FL
11 AM EDT SUN AUG 23 1998

EVEN THOUGH THE UPPER-LEVEL OUTFLOW TO THE WEST IS CURRENTLY BEING
IMPEDED A BIT...BONNIE HAS CONTINUED TO STRENGTHEN.  A HURRICANE
HUNTER PLANE IS FINDING WINDS OF AT LEAST 100 KNOTS AT THE 700 MB
LEVEL...AND WINDS AT 850 MB ARE PROBABLY HIGHER.  ON SATELLITE...
BONNIE HAS A CLASSICAL APPEARENCE.  THE COLD-TOPPED DENSE OVERCAST
SURROUNDING THE EYE HAS GROWN IN SIZE.  CURRENT INTENSITY ESTIMATE
IS 100 KNOTS...MAKING BONNIE A MAJOR HURRICANE.  SOME FURTHER
STRENGTHENING COULD OCCUR.  

RECON AND SATELLITE FIXES YIELD LITTLE MOTION OVER THE PAST SEVERAL
HOURS...SO THE GUIDANCE MODELS WERE INITIALIZED WITH A FORWARD
MOTION OF ZERO.  THE RESULTING OBJECTIVE TRACK FORECASTS ARE HIGHLY
DIVERGENT...WITH 72 HOUR PREDICTIONS RANGING FROM NEAR THE CAROLINA
COAST TO WELL OFFSHORE OF THE U.S. EAST COAST.  THE STEERING PATTERN
IS BY NO MEANS STRAIGHTFORWARD.  WATER VAPOR IMAGERY SHOWS THAT A
WEAK MID- TO UPPER-LEVEL TROUGH IS CURRENTLY IN THE VICINITY OF
BONNIE... AND HAS PROBABLY CAUSED THE STALLING OF THE HURRICANE.  IT
APPEARS THAT THIS TROUGH WILL BYPASS BONNIE...THEREFORE A SLOW
NORTHWESTWARD MOTION IS FORECAST TO RESUME.   WATER VAPOR WINDS FROM
THE UNIVERSITY OF WISCONSIN CIMSS SUGGESTS AN UPPER-LEVEL RIDGE
EXTENDING EASTWARD FROM NEAR THE FLORIDA-GEORGIA BORDER INTO THE
ATLANTIC FOR A COUPLE HUNDRED MILES...AND THIS COULD PREVENT A TURN
AWAY FROM THE COAST IF IT PERSISTS.  THE BIG QUESTION IS WHETHER
ANOTHER UPSTREAM TROUGH...CURRENTLY OVER THE NORTH-CENTRAL U.S.
...WILL EVENTUALLY PULL BONNIE AWAY FROM THE COAST.  ALL INTERESTS
ALONG THE EAST COAST OF THE U.S. SHOULD MAINTAIN THEIR VIGILANCE AND
MONITOR FUTURE ADVISORIES. 

ANOTHER MULTI-AIRCRAFT MISSION INVOLVING AIRCRAFT FROM BOTH NOAA AND
NASA WILL PROVIDE EXTENSIVE SAMPLING OF THE STEERING ENVIRONMENT
TODAY.  THEIR DATA SHOULD HELP IMPROVE THE INITIALIZATION AND BRING
THE TRACK PREDICTIONS TOGETHER...AND IMPROVE FORECAST CONFIDENCE.   

PASCH
 
FORECAST POSITIONS AND MAX WINDS
 
INITIAL     23/1500Z 24.2N  71.6W   100 KTS
12HR VT     24/0000Z 25.0N  72.5W   105 KTS
24HR VT     24/1200Z 26.5N  73.5W   110 KTS
36HR VT     25/0000Z 28.1N  74.3W   110 KTS
48HR VT     25/1200Z 29.8N  75.2W   110 KTS
72HR VT     26/1200Z 33.5N  76.5W   110 KTS
  
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