000 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