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HURRICANE BONNIE DISCUSSION NUMBER  17
NATIONAL WEATHER SERVICE MIAMI FL
5 PM EDT SUN AUG 23 1998

AFTER DRIFTING TO THE NORTH EARLIER TODAY...BONNIE APPEARS TO NOW BE
MOVING SLOWLY NORTHWESTWARD.  THE INFLUENCE OF THE MID- TO UPPER-
LEVEL TROUGH...THAT LIKELY INDUCED THE NORTHWARD NUDGE OF THE
HURRICANE...NOW APPEARS TO BE LESSENING AS IT BY PASSES BONNIE.  WE
ARE NOW FACED WITH THE DILEMMA OF THE FUTURE COURSE OF THIS
HURRICANE.  THE PROBLEM IS COMPOUNDED BY THE FACT THAT SOME OF OUR
BEST TRACK PREDICTION MODELS HAVE SHIFTED SIGNIFICANTLY TO THE LEFT
AS COMPARED TO THIS MORNING.  LOOKING AT SOME OF THE MODEL
FIELDS...THERE IS NOW A DISTINCT POSSIBILITY THAT BONNIE COULD BE
TRAPPED BENEATH A NARROW RIDGE ALONG ABOUT 36N LATITUDE OR SO.  IF
THIS IS THE CASE...BONNIE COULD REACH THE SOUTHEAST U.S. COAST NEAR
THE END OF THIS FORECAST PERIOD.

THE EYE HAS BECOME INDISTINCT OVER THE PAST FEW HOURS.  SINCE BONNIE
HAS BEEN DWELLING OVER THE SAME GENERAL AREA MOST OF TODAY...IT MAY
HAVE COOLED THE SURFACE WATERS UNDERNEATH IT AND THIS MAY HAVE
TEMPORARILY BRAKED THE STRENGTHENING TREND.  ANOTHER INHIBITING
FACTOR MAY HAVE THE ABOVEMENTIONED TROUGH.  HOWEVER THE HURRICANE
HAS A MASSIVE UPPER-LEVEL ANTICYCLONIC OUTFLOW OVER ALL BUT THE
NORTHWEST QUADRANT.  ALSO...THERE HAVE BEEN SOME DIURNAL
FLUCTUATIONS WHEREIN THE SYSTEM HAS BEEN STRENGTHENING MORE DURING
THE NIGHTTIME HOURS THE LAST COUPLE OF DAYS...AND BECOMING A LITTLE
LESS ORGANIZED AROUND MIDDAY.  SOME FURTHER INCREASE IN INTENSITY IS
CERTAINLY POSSIBLE DURING THE PERIOD.

ALL INTERESTS ALONG THE EAST COAST OF THE U.S. SHOULD MAINTAIN THEIR
VIGILANCE AND MONITOR FUTURE ADVISORIES.  WE HAVE INSERTED A
STATEMENT INTO THE ADVISORY THAT A HURRICANE WATCH MAY BE REQUIRED
FOR A PORTION OF THE SOUTHEAST U.S. COAST ON MONDAY
 
ANOTHER MULTI-AIRCRAFT MISSION INVOLVING AIRCRAFT FROM BOTH NOAA AND
NASA WILL PROVIDE EXTENSIVE SAMPLING OF THE STEERING ENVIRONMENT
TODAY.  THEIR OBSERVATIONS SHOULD HELP IMPROVE THE INITIALIZATION
AND BRING THE TRACK PREDICTIONS TOGETHER...AND IMPROVE CONFIDENCE IN
THIS VERY DIFFICULT FORECAST SITUATION.
 
PASCH
 
FORECAST POSITIONS AND MAX WINDS
 
INITIAL     23/2100Z 24.8N  71.8W   100 KTS
12HR VT     24/0600Z 25.3N  72.3W   105 KTS
24HR VT     24/1800Z 26.3N  73.0W   110 KTS
36HR VT     25/0600Z 27.6N  74.0W   110 KTS
48HR VT     25/1800Z 29.4N  75.4W   110 KTS
72HR VT     26/1800Z 33.0N  78.0W   110 KTS
 
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