000 WTNT41 KNHC 010855 TCDAT1 HURRICANE OPHELIA DISCUSSION NUMBER 35 NWS NATIONAL HURRICANE CENTER MIAMI FL AL162011 500 AM AST SAT OCT 01 2011 SINCE THE PREVIOUS ADVISORY...THE EYE HAS BECOME MORE DISTINCT IN INFRARED IMAGERY AND THE EYE TEMPERATURE HAS WARMED TO ABOUT 11 DEGREES CELSIUS. THE EYE OF OPHELIA PASSED DIRECTLY OVER NOAA BUOY 41049 AROUND 08Z...AND THE BUOY REPORTED A 1-MINUTE SUSTAINED WIND OF 84 KT WITH A GUST OF 101 KT AT A HEIGHT OF 5 METERS...AND A PRESSURE OF 951.9 MB. BASED ON THE BUOY PRESSURE AND SATELLITE INTENSITY ESTIMATES OF T5.5/102 KT FROM BOTH TAFB AND SAB...THE ADVISORY INTENSITY WILL REMAIN AT 105 KT. WIND RADII WERE ADJUSTED SLIGHTLY BASED ON WINDS OBTAINED FROM A 01/0106Z ASCAT OVERPASS. THE INITIAL MOTION IS A STEADY 360/15 KT. OPHELIA IS FORECAST TO CONTINUE MOVING NORTHWARD FOR THE NEXT 12 HOURS OR SO...AND THEN GRADUALLY TURN TOWARD THE NORTHEAST AND ACCELERATE AS THE HURRICANE COMES UNDER THE INFLUENCE OF INCREASING SOUTHWESTERLY STEERING FLOW AHEAD OF A DEEP-LAYER TROUGH CURRENTLY MOVING EASTWARD OFF THE U.S. EAST COAST. BY 48 HOURS...THE CYCLONE IS EXPECTED TO TURN SHARPLY EASTWARD AS IT ENTERS A BAND OF FAST-MOVING WESTERLIES NORTH OF 45N LATITUDE. BY THAT TIME...OPHELIA IS FORECAST TO BE OVER WATERS COLDER THAN 20C AND ALSO BEGIN TO MERGE WITH A STRONG FRONTAL SYSTEM...WHICH SHOULD INDUCE A QUICK TRANSITION INTO A POWERFUL POST-TROPICAL WINTER-TYPE CYCLONE. THE OFFICIAL FORECAST TRACK IS SIMILAR TO THE PREVIOUS ADVISORY...AND LIES DOWN THE MIDDLE OF THE TIGHTLY PACKED NHC MODEL GUIDANCE SUITE. THERE IS NO SIGNIFICANT CHANGE TO THE PREVIOUS INTENSITY FORECAST. OPHELIA COULD STRENGTHEN SLIGHTLY TODAY AS THE MAJOR HURRICANE REMAINS OVER SSTS NEAR 28C AND IN A VERTICAL SHEAR CONDITIONS OF LESS THAN 5 KT. BY 24 HOURS...HOWEVER...INCREASING SOUTHWESTERLY WIND SHEAR AND COOLER WATERS SHOULD INDUCE GRADUAL WEAKENING UNTIL THE 36-HOUR TIME PERIOD. AFTER THAT...OPHELIA WILL MOVE OVER MUCH COLDER WATER AND ENCOUNTER STRONG VERTICAL SHEAR OF MORE THAN 30 KT...WHICH SHOULD CAUSE MORE RAPID WEAKENING AND ALSO TRANSITION INTO AN EXTRATROPICAL CYCLONE. THE OFFICIAL INTENSITY FORECAST IS SIMILAR TO THE PREVIOUS ADVISORY AND IS CLOSE TO THE INTENSITY CONSENSUS MODEL...ICON. FORECAST POSITIONS AND MAX WINDS INIT 01/0900Z 27.7N 63.1W 105 KT 120 MPH 12H 01/1800Z 30.4N 62.8W 100 KT 115 MPH 24H 02/0600Z 34.8N 61.9W 95 KT 110 MPH 36H 02/1800Z 40.1N 60.3W 90 KT 105 MPH 48H 03/0600Z 44.8N 55.9W 60 KT 70 MPH 72H 04/0600Z 51.0N 36.0W 45 KT 50 MPH...POST-TROP/EXTRATROP 96H 05/0600Z...ABSORBED $$ FORECASTER STEWART