WTPA45 PHFO 231444 TCDCP5 HURRICANE OLAF DISCUSSION NUMBER 35 NWS CENTRAL PACIFIC HURRICANE CENTER HONOLULU HI EP192015 500 AM HST FRI OCT 23 2015 A RAGGED 10 NM WIDE EYE EMBEDDED WITHIN AN ASYMMETRIC DEEP CONVECTIVE RING DESCRIBES THE CENTRAL FEATURE FOR OLAF. SOME ADDITIONAL BANDING WITHIN THE NORTH AND EAST QUADRANTS GIVES US THE IMPRESSION THAT OLAF ORGANIZATION HAS IMPROVED SLIGHTLY SINCE LAST EVENING. SUBJECTIVE DVORAK SATELLITE INTENSITY ESTIMATES ARE UNCHANGED FROM EARLIER...5.5...102 KT...FROM ALL THREE SATELLITE CENTERS. HOWEVER...UW-CIMSS ADT INCREASED DRAMATICALLY TO AN UNREPRESENTATIVE 6.7...132 KT. GIVEN THE SLIGHTLY BETTER OVERALL SATELLITE PRESENTATION...AND AS A NOD TO THE ADT TREND...WE WILL ASSIGN 105 KT AS THE INITIAL INTENSITY FOR THIS ADVISORY. INITIAL MOTION IS JUST EAST OF DUE NORTH...OR 005/08 KT...AS OLAF CONTINUES MOVING INTO A WEAKNESS IN THE SUBTROPICAL RIDGE FAR NORTHEAST OF THE MAIN HAWAIIAN ISLANDS. A LARGE NORTHWARD COMPONENT WILL CONTINUE THROUGH THE FORECAST PERIOD...WITH A PAIR OF TROUGHS PASSING EASTWARD TO THE NORTH OF OLAF NUDGING THIS SYSTEM EVER MORE INSISTENTLY TO THE EAST THROUGH DAY FOUR. TRACK GUIDANCE HAS CHANGE VERY LITTLE THROUGH 96 HOURS. HOWEVER...GFS JOINED ECMWF IN DEPICTING A SUDDEN SWING TO THE NORTHWEST BETWEEN 96 AND 120 HOURS...DRAGGING CONSENSUS LEFTWARD LATE IN THE FORECAST PERIOD AS WELL. THIS MAY BE DUE TO BOTH GLOBAL MODELS SEEING A DECAPITATED OLAF SUDDENLY COMING UNDER THE INFLUENCE OF SHALLOW LOW LEVEL FLOW ALONG THE SOUTH FLANK OF THE SUBTROPICAL RIDGE AT THAT POINT. HOWEVER...BOTH GFS AND ECMWF KEEP OLAF RATHER STRONG ON DAYS FOUR AND FIVE...SO PERHAPS RIDGE STRENGTHENING TO THE NORTH OF OLAF IS SEEN. EITHER WAY...THE DAY FIVE FORECAST POINT WAS ADJUSTED TO THE LEFT TO ACCOUNT FOR THIS EFFECT...LEAVING THE REMAINING FORECAST POINTS PRETTY MUCH INTACT FROM LAST TIME. SHIPS AND UW-CIMSS CONTINUE TO DISAGREE ON THE AMOUNT OF SHEAR ACROSS OLAF...RANGING FROM 15 TO 25 KT...RESPECTIVELY. WE ASSUME THAT THE AMOUNT OF SHEAR PRESENT IS CLOSER TO THE LOWER VALUE SINCE THE INNER CORE OF OLAF APPEARS TO BE UNAFFECTED. INTENSITY GUIDANCE SHOWS WEAKENING ACROSS THE BOARD THROUGH THE NEXT FIVE DAYS AS SHEAR INCREASES AND SSTS DROP...WITH SHIPS DISSIPATING OLAF BY DAY FOUR. THE GLOBAL MODELS WEAKEN OLAF MUCH MORE SLOWLY...WITH GFS DEPICTING OLAF STILL AT TROPICAL STORM STRENGTH ON DAY FIVE. WE WILL KEEP THE SAME STEADY WEAKENING TREND FROM LAST TIME...EXCEPT FOR A BUMP UP TO 95 KT AT 24 HOURS TO ACCOUNT FOR THE INITIAL INTENSITY INCREASE. WE FORECAST OLAF WILL REMAIN A MINIMAL HURRICANE AT 72 HOURS...THEN WEAKEN TO A TROPICAL STORM AT 96 AND 120 HOURS. FORECAST POSITIONS AND MAX WINDS INIT 23/1500Z 15.9N 146.2W 105 KT 120 MPH 12H 24/0000Z 16.9N 145.9W 100 KT 115 MPH 24H 24/1200Z 18.3N 145.5W 95 KT 110 MPH 36H 25/0000Z 19.5N 144.9W 90 KT 105 MPH 48H 25/1200Z 20.7N 144.1W 85 KT 100 MPH 72H 26/1200Z 23.3N 141.8W 65 KT 75 MPH 96H 27/1200Z 25.8N 137.9W 60 KT 70 MPH 120H 28/1200Z 30.3N 138.0W 45 KT 50 MPH $$ FORECASTER POWELL