Hurricane BILL

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HURRICANE BILL DISCUSSION NUMBER  33
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL   AL032009
1100 AM AST SUN AUG 23 2009
 
AFTER THE LAST AIR FORCE MISSION INTO BILL....JUST BEFORE 1200
UTC...THE CLOUD PATTERN OF THE HURRICANE HAS BEGUN TO LOOK A LITTLE
LESS TROPICAL.  THE AIRCRAFT REPORTED A PEAK FLIGHT-LEVEL WIND OF
105 KT OVER THE EASTERN QUADRANT AROUND 1100 UTC.  TYPICALLY THIS
WOULD SUPPORT A HIGHER INTENSITY OF GREATER THAN 75 KT. 
HOWEVER...SINCE THE CYCLONE IS TRAVERSING COOLER WATERS...IT IS
BECOMING INCREASINGLY DIFFICULT FOR IT TO TRANSPORT STRONG WINDS TO
THE SURFACE.  GIVEN THAT...ALONG WITH THE DETERIORATION OF THE
CLOUD PATTERN...THE CURRENT INTENSITY IS HELD AT 75 KT.  BILL IS
EXPECTED TO BECOME AN EXTRATROPICAL STORM WITHIN A DAY OR SO AND
GRADUALLY WEAKEN AS IT MOVES RAPIDLY ACROSS THE NORTH ATLANTIC. 
GLOBAL MODELS SUGGEST THAT THE SYSTEM WILL MERGE WITH A BROADER
CYCLONIC CIRCULATION NEAR THE BRITISH ISLES IN 3-4 DAYS.
 
CURRENT MOTION IS AROUND 045/29.  BILL SHOULD CONTINUE ACCELERATING
OVER THE NEXT 24-36 HOURS AS IT BECOMES WELL EMBEDDED IN THE
MID-LATITUDE WESTERLIES.  SOME SLOWING OF THE FORWARD SPEED IS
LIKELY LATER IN THE PERIOD AS THE EXTRATROPICAL REMNANT OF BILL
INTERACTS WITH THE LARGE CYCLONIC CIRCULATION OVER THE NORTHEAST
ATLANTIC.  THE CURRENT OFFICIAL TRACK FORECAST IS SIMILAR TO THE
PREVIOUS ONE.
 
LARGE AND DANGEROUS SWELLS ASSOCIATED WITH BILL WILL BE IMPACTING
THE CANADIAN MARITIMES DURING THE NEXT 24 HOURS.  SWELLS ALONG THE
EAST COAST OF THE UNITED STATES SHOULD BE DIMINISHING TODAY.
  
FORECAST POSITIONS AND MAX WINDS
 
INITIAL      23/1500Z 43.3N  64.0W    75 KT
 12HR VT     24/0000Z 46.3N  59.1W    65 KT
 24HR VT     24/1200Z 49.0N  49.7W    55 KT...EXTRATROPICAL
 36HR VT     25/0000Z 50.8N  37.4W    45 KT...EXTRATROPICAL
 48HR VT     25/1200Z 52.5N  26.5W    35 KT...EXTRATROPICAL
 72HR VT     26/1200Z 57.0N   8.0W    30 KT...EXTRATROPICAL
 96HR VT     27/1200Z...MERGED WITH ANOTHER LOW
 
$$
FORECASTER PASCH
 
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