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TROPICAL STORM BONNIE DISCUSSION NUMBER   7
NATIONAL WEATHER SERVICE MIAMI FL
4 AM EST FRI AUG 21 1998
 
NO RECON DATA THIS MORNING UNTIL 12Z.  LIMITED SATELLITE PICTURES
SUGGEST NO SIGNIFICANT CHANGE IN STRUCTURE OR INTENSITY OVER THE
PAST 6 HOURS.  MAXIMUM WIND SPEED IS AGAIN ESTIMATED TO BE 45 KT.
THE INITIAL MOTION IS STILL AROUND 290 DEGREES...BUT MAY HAVE
DECREASED A LITTLE...TO NEAR 19 KT.
 
NEARLY 50 SONDES DEPLOYED BY NOAA AIRCRAFT LAST EVENING HAVE
CONTRIBUTED TO THE MODEL INITIALIZATION.  THEY GIVE A HIGH...AND
PERHAPS UNPRECEDENTED...DENSITY OF SUCH OBSERVATIONS.  POSSIBLY AS A
RESULT...THE TWO TRACK FORECAST SOLUTIONS HAVE CONVERGED
SOMEWHAT...EACH CAMP IN A WAY COMPROMISING ON THE EXTREMES OF
YESTERDAY.  MOST OF THE MODELS STILL SHOW A TURN TOWARD THE
NORTH...WITH THE GFDL TRACK TO THE SOUTHWEST.  THE BIFURCATION IS
NOT AS EXTREME AS YESTERDAY...HOWEVER...WITH THE GFDL 72 HOUR
POSITION ABOUT 250 NM SOUTHWEST OF THE OTHERS...INSTEAD OF 500 NM.  
THIS MODEST CONVERGENCE OF TRACK FORECASTS IS CENTERED ROUGHLY ALONG
OUR PREVIOUS FORECASTS AND THE NEW NHC TRACK REPRESENTS A GENERAL
EXTENSION OF THE PREVIOUS THINKING.  DECELERATION IS EXPECTED.
 
ALL AVAILABLE GUIDANCE...AND THE OFFICIAL FORECAST...INDICATE
STRENGTHENING.

THE WATCHES AND WARNINGS FOR THE CARIBBEAN WILL LIKELY BE
DISCONTINUED LATER THIS MORNING.  A TROPICAL STORM WATCH IS NOW IN
EFFECT FOR THE SE BAHAMAS AND TURKS AND CAICOS.  THIS COULD BE
UPGRADED LATER TODAY.
 
RAPPAPORT
 
FORECAST POSITIONS AND MAX WINDS
 
INITIAL     21/0900Z 19.9N  64.0W    45 KTS
12HR VT     21/1800Z 20.8N  66.3W    50 KTS
24HR VT     22/0600Z 22.0N  68.9W    60 KTS
36HR VT     22/1800Z 23.4N  71.4W    65 KTS
48HR VT     23/0600Z 24.9N  73.0W    75 KTS
72HR VT     24/0600Z 28.0N  74.0W    85 KTS
 
 
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