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| #289425 (Received by flhurricane at: 10:46 AM 19.Aug.2009) TCDAT3 HURRICANE BILL DISCUSSION NUMBER 17 NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL AL032009 1100 AM AST WED AUG 19 2009 A NOAA P-3 PLANE ON A RESEARCH MISSION HAS BEEN PROVIDING EXCELLENT DATA FROM BILL DURING THE PAST SEVERAL HOURS. THERE WAS A PEAK FLIGHT-LEVEL WIND OF 132 KNOTS TWO HOURS AGO AND THE SFMR REPORTED PEAK WINDS AROUND 105 KNOTS. DATA FROM THE PLANE ALSO SHOW THAT BILL HAS A LARGE WIND FIELD AND A 30 NMI WIDE EYE. THE LATEST EXTRAPOLATED MINIMUM CENTRAL PRESSURE WAS 950 MB. ALTHOUGH THE RING OF DEEP CONVECTION SURROUNDING THE EYE OBSERVED ON SATELLITE HAS WEAKENED DURING THE PAST COUPLE OF HOURS...THE T-NUMBERS REMAIN AROUND 6.0 ON THE DVORAK SCALE. INITIAL INTENSITY IS KEPT AT 115 KT IN THIS ADVISORY. THE LARGE SCALE ENVIRONMENT IS FAVORABLE FOR ADDITIONAL INTENSIFICATION SINCE BILL IS HEADING FOR A WARMER OCEAN AND THE SHEAR IS EXPECTED TO BE LOW FOR THE NEXT TWO TO THREE DAYS. HOWEVER...MOST LIKELY THERE WILL BE FLUCTUATIONS IN INTENSITY IN THIS PERIOD CONTROLLED BY EYEWALL REPLACEMENT CYCLES. BEYOND 72 HOURS...THE OCEAN IS COOLER AND A GRADUAL WEAKENING SHOULD BEGIN... BUT BILL IS FORECAST TO REMAIN A HURRICANE THROUGH FIVE DAYS. THERE HAS BEEN NO CHANGE IN THE STEERING CURRENTS AND BILL CONTINUES TO MOVE TOWARD THE WEST-NORTHWEST OR 300 DEGREES AT 16 KNOTS AROUND THE AZORES-BERMUDA HIGH. THIS GENERAL MOTION SHOULD CONTINUE FOR A COUPLE OF DAYS. THEREAFTER...A LARGE MID-LATITUDE TROUGH IS EXPECTED TO SWING EASTWARD OVER THE EASTERN UNITED STATES...FORCING BILL TO TURN NORTHWARD A GOOD DISTANCE AWAY FROM THE U.S. EAST COAST. THIS IS IN AGREEMENT WITH THE SOLUTION PROVIDED BY MOST OF THE DYNAMICAL MODELS...WHICH IN FACT HAVE BEEN QUITE CONSISTENT IN TURNING BILL NORTHWARD FOR THE PAST SEVERAL RUNS. THE OFFICIAL FORECAST IS VERY SIMILAR TO THE PREVIOUS ONE AND IS VERY CLOSE TO THE MODEL CONSENSUS. BECAUSE BILL IS A LARGE AND STRONG HURRICANE...SWELLS TRIGGERED BY THE HURRICANE SHOULD AFFECT THE NORTHERN LEEWARD ISLANDS...BERMUDA AND PORTIONS OF THE EASTERN UNITED STATES DURING THE NEXT FEW DAYS. FORECAST POSITIONS AND MAX WINDS INITIAL 19/1500Z 18.7N 56.3W 115 KT 12HR VT 20/0000Z 19.9N 58.3W 120 KT 24HR VT 20/1200Z 21.7N 61.0W 125 KT 36HR VT 21/0000Z 23.5N 63.5W 125 KT 48HR VT 21/1200Z 26.0N 65.5W 120 KT 72HR VT 22/1200Z 32.0N 68.5W 115 KT 96HR VT 23/1200Z 38.5N 67.0W 100 KT 120HR VT 24/1200Z 47.0N 58.0W 75 KT $$ FORECASTER AVILA |
