Hurricane BILL

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HURRICANE BILL DISCUSSION NUMBER  25
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL   AL032009
1100 AM AST FRI AUG 21 2009
 
AFTER SOME DETERIORATION OF THE CLOUD PATTERN EARLY THIS
MORNING...VISIBLE SATELLITE IMAGES INDICATE THAT THE EYE HAS BECOME 
APPARENT AGAIN ALTHOUGH IS NOT AS DISTINCT IT WAS YESTERDAY. 
MICROWAVE IMAGES SHOW A CONVECTIVE RING ASSOCIATED WITH THE EYEWALL
WITH AN OUTER CONVECTIVE BAND.  AT THIS POINT IT IS DIFFICULT TO
KNOW WHETHER THIS IS THE BEGINNING OF THE FORMATION OF A SECONDARY
EYEWALL.  IT IS ALSO POSSIBLE THAT THE WEAKENING OVERNIGHT WAS 
RELATED TO AN EYEWALL REPLACEMENT CYCLE. THE AVERAGE OF THE LATEST
OBJECTIVE AND SUBJECTIVE DVORAK T-NUMBERS INDICATE THAT INITIAL
INTENSITY CAN BE ADJUSTED DOWN TO 100 KT.  AN AIR FORCE HURRICANE
HUNTER PLANE WILL CHECK THE INTENSITY LATER TODAY.  THE HURRICANE
STILL HAS TO MOVE OVER THE WARMEST OCEAN YET TODAY AND
SATURDAY...AND THE SHEAR IS LOW AS DIAGNOSED BY THE SHIPS MODEL.
BILL HAS THE POTENTIAL TO RESTRENGTHEN A LITTLE BUT MOST LIKELY THE
HURRICANE WILL EXPERIENCE SOME FLUCTUATIONS IN INTENSITY DURING THE
NEXT 24 HOURS. THEREAFTER...SHEAR AND A COLDER OCEAN SHOULD WORK
AGAINST INTENSIFICATION AND BILL SHOULD BEGIN ITS EXTRATROPICAL
TRANSITION BEYOND 72 HOURS.

BILL IS MOVING TOWARD THE NORTHWEST OR 325 DEGREES AT 16 KNOTS WHILE
EMBEDDED IN VERY WELL-ESTABLISHED STEERING CURRENTS ASSOCIATED WITH
THE AZORES-BERMUDA HIGH. BILL IS ALREADY REACHING THE SOUTHWESTERN
EDGE OF THE RIDGE AND SOON WILL BECOME STEERED NORTHWARD AND
NORTHEASTWARD BY THE FLOW BETWEEN THE HIGH AND A LARGE MID-LATITUDE
TROUGH DEVELOPING OVER THE EASTERN UNITED STATES. THESE TWO
FEATURES ARE BEING HANDLED CONSISTENTLY ACROSS MOST OF THE
DYNAMICAL MODELS AND CONSEQUENTLY THE TRACK GUIDANCE IS TIGHTLY
PACKED. THE FACT THAT TRACK GUIDANCE IS IN VERY GOOD AGREEMENT
INCREASES MY CONFIDENCE IN THE TRACK FORECAST.    

LARGE SWELLS GENERATED BY THIS HURRICANE WILL AFFECT A LARGE PORTION
OF THE WESTERN NORTH ATLANTIC COASTAL AREA DURING THE NEXT FEW
DAYS.  THESE SWELLS WILL LIKELY CAUSE EXTREMELY DANGEROUS SURF AND
LIFE-THREATENING RIP CURRENTS.  PLEASE CONSULT STATEMENTS ISSUED BY
YOUR LOCAL WEATHER OFFICE AND METEOROLOGICAL SERVICES FOR MORE
DETAILS.

 
FORECAST POSITIONS AND MAX WINDS
 
INITIAL      21/1500Z 27.6N  66.3W   100 KT
 12HR VT     22/0000Z 29.8N  67.7W   100 KT
 24HR VT     22/1200Z 33.0N  68.5W   100 KT
 36HR VT     23/0000Z 36.5N  68.4W    90 KT
 48HR VT     23/1200Z 41.0N  66.0W    80 KT
 72HR VT     24/1200Z 48.5N  52.0W    60 KT
 96HR VT     25/1200Z 53.5N  27.5W    50 KT...EXTRATROPICAL
120HR VT     26/1200Z 57.5N  10.0W    40 KT...EXTRATROPICAL
 
$$
FORECASTER AVILA
 
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