000 WTNT43 KNHC 212040 TCDAT3 HURRICANE BILL DISCUSSION NUMBER 26 NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL AL032009 500 PM AST FRI AUG 21 2009 AN AIR FORCE HURRICANE HUNTER AIRCRAFT REACHED BILL THIS AFTERNOON AND FOUND THAT THE CENTRAL PRESSURE HAS REMAINED AROUND 954 MB...BUT THE WINDS HAVE DECREASED AND INITIAL INTENSITY IS NOW 90 KT. THE PLANE REPORTED A SMALL EYE OF 14 N MI DIAMETER. GIVEN THE CONCENTRIC RING STRUCTURE OBSERVED ON MICROWAVE AND THE DOUBLE WIND MAXIMA PROVIDED BY THE PLANE...IT IS LIKELY THAT THE HURRICANE IS GOING THROUGH AN EYEWALL REPLACEMENT AND THE REASON FOR THE CURRENT WEAKENING. THERE IS AN OPPORTUNITY FOR BILL TO REGAIN SOME STRENGTH DURING THE NEXT 12 TO 24 HOURS WHILE THE SHEAR IS LOW AND BEFORE THE HURRICANE REACHES COOLER WATERS. THEREAFTER...A STEADY WEAKENING IS INDICATED AND BY 72 HOURS...BILL SHOULD ALREADY BE AN EXTRATROPICAL CYCLONE INTERACTING WITH THE HIGH LATITUDE WESTERLIES. BILL IS NOW MOVING TOWARD THE NORTH-NORTHWEST OR 340 DEGREES AT 17 KNOTS. THE HURRICANE SHOULD GRADUALLY TURN MORE TO THE NORTH AROUND THE BERMUDA-AZORES HIGH TONIGHT AND SATURDAY AND SHOULD BE FORCED TO RECURVE AS A LARGE MID-LATITUDE TROUGH MOVES EASTWARD ACROSS THE EASTERN UNITED STATES. THERE HAS NOT BEEN ANY CHANGE IN TRACK GUIDANCE WHICH IN FACT CONTINUES TO BE TIGHTLY PACKED...MAINTAINING HIGH 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. AT THIS TIME...TROPICAL-STORM-FORCE WINDS ARE NOT FORECAST TO REACH NEW ENGLAND. HOWEVER...A SLIGHT SHIFT OF THE FORECAST TRACK TO THE LEFT WOULD REQUIRE A TROPICAL STORM WATCH OR WARNING TONIGHT. THE WIND SPEED PROBABILITY PRODUCT INDICATES THAT THERE IS ROUGHLY A 25 PERCENT CHANCE OF THESE WINDS REACHING EXTREME SOUTHEASTERN NEW ENGLAND. FORECAST POSITIONS AND MAX WINDS INITIAL 21/2100Z 29.4N 66.9W 90 KT 12HR VT 22/0600Z 31.7N 68.0W 100 KT 24HR VT 22/1800Z 35.1N 68.4W 100 KT 36HR VT 23/0600Z 39.0N 67.2W 85 KT 48HR VT 23/1800Z 43.0N 64.0W 75 KT 72HR VT 24/1800Z 49.5N 47.0W 50 KT...EXTRATROPICAL 96HR VT 25/1800Z 54.5N 20.0W 45 KT...EXTRATROPICAL 120HR VT 26/1800Z 60.0N 6.0W 35 KT...EXTRATROPICAL $$ FORECASTER AVILA