Tropical Storm BILL

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TROPICAL STORM BILL DISCUSSION NUMBER   5
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL   AL032009
1100 AM AST SUN AUG 16 2009
 
BILL IS DISPLAYING A BEAUTIFUL CURVED BAND PATTERN ON SATELLITE
IMAGERY THIS MORNING WITH A NEW BURST OF CONVECTION OCCURRING NEAR
THE CENTER.  A 0808 UTC QUIKSCAT PASS SHOWED MAXIMUM WINDS OF AT
LEAST 45 KT...AND DVORAK SATELLITE INTENSITY ESTIMATES ARE BETWEEN
45-55 KT.  THE INITIAL INTENSITY IS SET TO 50 KT AS A BLEND OF THE
ABOVE DATA.
 
A SERIES OF MICROWAVE PASSES AND VISIBLE IMAGES HAVE CONFIRMED THAT
THE CENTER HAS SHIFTED A LITTLE BIT TO THE NORTH AND THE INITIAL
MOTION IS ABOUT 285/14.  A CONTINUED WEST-NORTHWEST MOTION IS
EXPECTED FOR THE NEW FEW DAYS DUE TO SUBTROPICAL RIDGING TO THE
NORTH OF BILL.  ALL OF THE GLOBAL MODELS BESIDES THE UKMET SHOW
THE TROPICAL CYCLONE MOVING TO THE NORTH OF THE LEEWARD ISLANDS AS A
BREAK IN THE RIDGE FORMS AT ABOUT 65W.  MODEL GUIDANCE HAS SHIFTED
TO THE NORTHEAST THIS MORNING...AND THE OFFICIAL FORECAST FOLLOWS
THAT TREND.
 
ENVIRONMENTAL CONDITIONS APPEAR FAVORABLE FOR CONTINUED
INTENSIFICATION DUE TO LIGHT SHEAR AND WARM WATERS.  SSTS BEGIN TO
RISE MORE SIGNIFICANTLY IN A COUPLE OF DAYS AND THE NHC INTENSITY
FORECAST COULD BE CONSERVATIVE AFTER THAT TIME.  ALL RELIABLE
GUIDANCE SHOWS THIS SYSTEM EVENTUALLY BECOMING A MAJOR HURRICANE...
THOUGH AT DIFFERING TIME PERIODS WITH THE STATISTICAL GUIDANCE
SHOWING IT HAPPENING EARLIER THAN THE DYNAMICAL MODELS.  THE NHC
FORECAST IS RAISED FROM THE PREVIOUS ONE...AND IS IN GOOD AGREEMENT
WITH THE SHIPS/LGEM THROUGH 72 HOURS.  THE INTENSITY FORECAST IS
LEVELED OFF AFTER 96 HOURS DUE THE POSSIBILITY OF WESTERLY SHEAR
DEVELOPING...AS SUGGESTED BY THE GFS/ECMWF MODELS.
 
THE QUIKSCAT PASS FROM THIS MORNING SHOWED THAT THE WIND FIELD WITH
BILL HAS EXPANDED...AND CONSEQUENTLY THE INITIAL 12 FT SEAS AND
FORECAST WIND RADII ARE LARGER THAN THE PREVIOUS FORECAST.

 
FORECAST POSITIONS AND MAX WINDS
 
INITIAL      16/1500Z 12.1N  38.4W    50 KT
 12HR VT     17/0000Z 12.6N  40.4W    60 KT
 24HR VT     17/1200Z 13.4N  43.1W    70 KT
 36HR VT     18/0000Z 14.3N  45.9W    80 KT
 48HR VT     18/1200Z 15.2N  48.6W    90 KT
 72HR VT     19/1200Z 17.5N  54.0W   100 KT
 96HR VT     20/1200Z 20.5N  59.0W   105 KT
120HR VT     21/1200Z 24.0N  63.5W   105 KT
 
$$
FORECASTER BLAKE
 
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