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HURRICANE BONNIE DISCUSSION NUMBER  28
NATIONAL WEATHER SERVICE MIAMI FL
11 PM EDT TUE AUG 25 1998
 
FORWARD SPEED APPEARS TO HAVE SLOWED JUST A BIT...TO NEAR 12 KNOTS.
OTHERWISE THE TRACK IS ABOUT THE SAME AS BEFORE...AND ALL OF OUR
GUIDANCE...ASIDE FROM SHALLOW LAYER STEERING WHICH IS NOT VALID FOR
A HURRICANE...SHOW A TURN TO THE NORTH BY MORNING.  SO...VERY LITTLE
CHANGE IS MADE FROM THE PREVIOUS OFFICIAL FORECAST.  IN FACT...THE
SLIGHT SLOWING OF THE FORWARD SPEED MAY BE PRESAGING A CHANGE IN
DIRECTION.  A MID- TO UPPER-LEVEL SHORTWAVE TROUGH IS APPROACHING
THE NORTHEASTERN U.S. AND THIS FEATURE SHOULD BRING ABOUT THE
EXPECTED TURN TO THE RIGHT.  IN 24 TO 36 HOURS BONNIE IS EXPECTED TO
BE MOVING NORTHEASTWARD WITH AN ACCELERATING FORWARD SPEED.
 
OBVIOUSLY THERE IS CONCERN THAT THE NORTHWARD TURN HAS NOT TAKEN
PLACE YET.  HOWEVER...WE EMPHASIZE THAT ONE SHOULD NOT FOCUS ON THE
PRECISE TRACK...ESPECIALLY SINCE BONNIE HAS SUCH A LARGE ENVELOPE OF
HURRICANE FORCE WINDS.  EVEN IF THE CURRENT NORTH-NORTHWEST MOTION
CONTINUES LONGER THAN FORECAST...BONNIE WOULD STILL MAKE LANDFALL
WITHIN THE HURRICANE WARNING AREA.
 
INTENSITY IS ESSENTIALLY UNCHANGED.  HURRICANE HUNTERS COULD NOT
FIND AN EYE...YET THEY FOUND WINDS TO 114 KNOTS AT THE 700 MB FLIGHT
LEVEL OVER THE NORTHEAST QUADRANT A FEW HOURS AGO.  CLOUD TOPS ON
SATELLITE IMAGERY ARE NOT VERY COLD AND DVORAK ESTIMATES OF
INTENSITY ARE SIGNIFICANTLY LOWER THAN THOSE PROVIDED BY THE
AIRCRAFT.  THIS UNDERSCORES THE GREAT VALUE OF AERIAL RECONNAISSANCE
IN HURRICANES THAT ARE THREATENING POPULATED COASTAL AREAS.
 
EVEN THOUGH SOME FLUCTUATIONS ARE POSSIBLE...NO SIGNIFICANT CHANGE
IN INTENSITY IS FORECAST UNTIL BONNIE PASSES THE OUTER BANKS.
WEAKENING IS FORECAST LATER ON AS IT ENCOUNTERS WESTERLY SHEAR AND
COOLER WATERS.
 
PASCH
 
FORECAST POSITIONS AND MAX WINDS
 
INITIAL     26/0300Z 31.6N  76.8W   100 KTS
12HR VT     26/1200Z 33.4N  77.3W   100 KTS
24HR VT     27/0000Z 35.9N  76.2W   100 KTS...INLAND
36HR VT     27/1200Z 38.2N  73.1W    80 KTS
48HR VT     28/0000Z 41.0N  67.0W    70 KTS
72HR VT     29/0000Z 47.0N  50.0W    60 KTS
 
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