000 WTNT42 KNHC 062045 TCDAT2 HURRICANE PHILIPPE DISCUSSION NUMBER 51 NWS NATIONAL HURRICANE CENTER MIAMI FL AL172011 500 PM AST THU OCT 06 2011 PHILIPPE HAS CONTINUED TO BECOME BETTER ORGANIZED THIS AFTERNOON AS AN EYE IN THE VISIBLE IMAGERY HAS BECOME ESTABLISHED INSIDE A RELATIVELY SMALL CENTRAL DENSE OVERCAST. BOTH TAFB AND SAB SUBJECTIVE DVORAK ANALYSES GIVE A CURRENT-INTENSITY NUMBER OF 4.5...OR ABOUT 77 KT. A CIMSS AMSU ESTIMATE SUGGESTS 75 KT FROM A 1649Z POLAR-ORBITING SATELLITE PASS. THE CIMSS ADVANCED DVORAK TECHNIQUE INDICATE A SLIGHTLY STRONGER 82 KT. A BLEND OF THESE GIVES AN INITIAL INTENSITY OF 75 KT...WHICH MAY BE SOMEWHAT CONSERVATIVE. A 1228Z ASCAT SCATTEROMETER PASS PROVIDED THE WIND RADII ANALYSIS...EVEN SMALLER THAN ESTIMATED EARLIER. PHILIPPE IS BEING STEERED TOWARD THE NORTHEAST AT ABOUT 11 KT... PRIMARILY DUE TO THE INFLUENCE OF A LARGE DEEP-LAYER EXTRATROPICAL LOW CENTERED OVER THE CANADIAN MARITIMES. THE MULTI-MODEL CONSENSUS IS IN VERY GOOD AGREEMENT ON AN ACCELERATION OF PHILIPPE IN THE SAME GENERAL DIRECTION DURING THE NEXT FEW DAYS. THE MODELS INDICATE A SLOWING OF THE FORWARD SPEED AS THE CYCLONE OCCLUDES AROUND DAYS THREE AND FOUR BEFORE ACCELERATING A FINAL TIME IN THE FAR NORTH ATLANTIC AROUND DAY FIVE. THE TRACK PREDICTION IS VERY CLOSE TO BOTH THE CONSENSUS AND THE PREVIOUS ADVISORY. THE SHARP GRADIENT OF INFRARED CLOUD TOP TEMPERATURES ALONG THE SOUTHWESTERN FLANK OF PHILIPPE MAY BE INDICATIVE OF THE EXPECTED INCREASE IN VERTICAL SHEAR. EVEN THOUGH PHILIPPE WILL BE PASSING OVER A SUFFICIENTLY WARM SEA SURFACE TO SUSTAIN A TROPICAL CYCLONE...THE COMBINATION OF STRONG VERTICAL SHEAR AND A DRY STABLE ATMOSPHERE SHOULD LEAD TO GRADUAL WEAKENING DURING THE NEXT TWO DAYS. THE DYNAMICAL HURRICANE MODELS HAVE BACKED OFF FROM THEIR EARLIER INSISTENCE OF CONTINUED INTENSIFICATION. THE FORECAST IS SLIGHTLY LOWER THAN THE INTENSITY CONSENSUS AND VERY SIMILAR TO THE PREVIOUS ADVISORY. AROUND 36 TO 48 HOURS...EXTRATROPICAL TRANSITION SHOULD OCCUR AS A COLD FRONT WRAPS AROUND THE CYCLONE. THE EXTRATROPICAL PORTION OF THE FORECAST IS BASED PRIMARILY ON GUIDANCE FROM THE OCEAN PREDICTION CENTER. FORECAST POSITIONS AND MAX WINDS INIT 06/2100Z 28.7N 59.0W 75 KT 85 MPH 12H 07/0600Z 29.5N 57.7W 75 KT 85 MPH 24H 07/1800Z 30.4N 55.2W 65 KT 75 MPH 36H 08/0600Z 31.9N 51.4W 60 KT 70 MPH 48H 08/1800Z 35.3N 47.0W 55 KT 65 MPH...POST-TROP/EXTRATROP 72H 09/1800Z 40.5N 44.5W 55 KT 65 MPH...POST-TROP/EXTRATROP 96H 10/1800Z 45.0N 41.0W 45 KT 50 MPH...POST-TROP/EXTRATROP 120H 11/1800Z 54.0N 34.0W 40 KT 45 MPH...POST-TROP/EXTRATROP $$ FORECASTER LANDSEA/PASCH