804 
 WTNT43 KNHC 230241
 TCDAT3
 HURRICANE BILL DISCUSSION NUMBER  31
 NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL   AL032009
 1100 PM AST SAT AUG 22 2009
  
 AFTER DIMINISHING FOR A TIME...INFRARED SATELLITE IMAGERY SHOWS A
 RECENT INCREASE OF COLD CLOUD TOPS NEAR AND TO THE NORTH OF THE
 CENTER OF BILL. WHILE THE EYE IS NOT READILY APPARENT IN
 GEOSTATIONARY IMAGERY...MICROWAVE IMAGERY STILL SHOWS AT LEAST A
 PARTIAL EYEWALL NORTH OF THE CENTER. THE INITIAL INTENSITY IS HELD
 AT 75 KT FOR THIS ADVISORY BASED ON FINAL CI-NUMBERS OF 4.5 FROM
 TAFB AND SAB AT 0000 UTC. AN AIR FORCE RESERVE HURRICANE HUNTER
 AIRCRAFT WILL BE INVESTIGATING BILL LATER TONIGHT AND SUNDAY
 MORNING...AND WILL PROVIDE ADDITIONAL INFORMATION ON THE
 LOCATION...STRUCTURE AND INTENSITY OF BILL.
  
 OVER THE PAST FEW HOURS...BILL APPEARS TO HAVE BEEN MOVING JUST EAST
 OF DUE NORTH...AND THE INITIAL MOTION ESTIMATE IS 015/22. THE TRACK
 MODEL GUIDANCE REMAINS IN EXCELLENT AGREEMENT ON THE RECURVATURE OF
 BILL IN THE NEXT COUPLE OF DAYS. THE OFFICIAL TRACK FORECAST IS
 BASICALLY AN UPDATE OF THE PREVIOUS PACKAGE...AND LIES NEAR THE
 MIDDLE OF THE TIGHTLY CLUSTERED TRACK GUIDANCE THROUGH 48 HOURS...
 SHOWING A TURN TOWARD THE NORTHEAST AND EAST-NORTHEAST WITH AN
 INCREASE IN FORWARD SPEED. BEYOND THAT TIME...THE TRACK FORECAST
 LIES SOUTH OF THE MODEL CONSENSUS AND IS IN BEST AGREEMENT WITH THE
 GFS ENSEMBLE MEAN AS THE POST-TROPICAL BILL APPROACHES THE BRITISH
 ISLES LATE IN THE FORECAST PERIOD.
  
 BILL WILL SOON BE MOVING ACROSS THE NORTH WALL OF THE GULF STREAM
 AND INTO A MORE BAROCLINIC ENVIRONMENT. MOST OF THE GLOBAL MODEL
 GUIDANCE SHOWS THAT BILL WILL BE EXTRATROPICAL BY 48 HOURS...AND
 THE CYCLONE SHOULD BE WELL INTO THE TRANSITION PROCESS BY EARLY
 MONDAY AS IT MOVES AWAY FROM NEWFOUNDLAND. THE OFFICIAL INTENSITY
 FORECAST SHOWS SLOW WEAKENING THROUGH 24 HOURS DUE TO COOLER SEA
 SURFACE TEMPERATURES AND INCREASING VERTICAL WIND SHEAR. BEYOND
 THAT TIME...A MORE SIGNIFICANT DECREASE IN INTENSITY IS FORECAST...
 ALONG WITH A LARGE EXPANSION OF THE 34-KT WIND RADII...AS BILL
 COMPLETES EXTRATROPICAL TRANSITION. 
  
 LARGE SWELLS GENERATED BY BILL ARE STILL AFFECTING THE EAST COAST OF
 THE UNITED STATES. THESE SWELLS WILL CONTINUE TO SPREAD NORTHWARD
 INTO THE CANADIAN MARITIMES ON SUNDAY...CAUSING 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      23/0300Z 39.1N  67.8W    75 KT
  12HR VT     23/1200Z 42.3N  65.7W    70 KT
  24HR VT     24/0000Z 46.3N  59.2W    60 KT
  36HR VT     24/1200Z 49.3N  49.0W    45 KT
  48HR VT     25/0000Z 51.0N  37.0W    40 KT...EXTRATROPICAL
  72HR VT     26/0000Z 53.0N  16.5W    30 KT...EXTRATROPICAL
  96HR VT     27/0000Z 60.0N   6.0W    30 KT...EXTRATROPICAL
 120HR VT     28/0000Z 64.0N   4.0W    25 KT...EXTRATROPICAL
  
 $$
 FORECASTER BRENNAN