WTPA45 PHFO 250859

TCDCP5



HURRICANE OLAF DISCUSSION NUMBER  42

NWS CENTRAL PACIFIC HURRICANE CENTER HONOLULU HI   EP192015

1100 PM HST SAT OCT 24 2015



OLAF REMAINS RATHER WELL-ORGANIZED THIS EVENING...WITH INFRARED

SATELLITE IMAGERY REVEALING A RAGGED BUT CLOUD-FREE EYE DURING THE

PAST FEW HOURS. 0327Z WINDSAT AND 0423Z SSMS MICROWAVE PASSES ALSO

DEPICTED A WELL-DEFINED EYE. HOWEVER...DEEP CONVECTION AROUND THE

EYE HAS WEAKENED INTERMITTENTLY DURING THE EVENING...AND THE EYE HAS

BEEN OPEN TO THE SOUTH AT TIMES. SUBJECTIVE DVORAK CURRENT INTENSITY

ESTIMATES CAME IN AT 4.5/77 KT FROM ALL THREE AGENCIES...WHILE THE

UW-CIMSS ADT CURRENT INTENSITY ESTIMATE REMAINS SIGNIFICANTLY

STRONGER AT 5.3/97 KT. THE INITIAL INTENSITY FOR THIS ADVISORY HAS

BEEN LOWERED TO 80 KT.



OLAF APPEARS TO HAVE SLOWED DOWN AND TURNED SLIGHTLY TO THE RIGHT

DURING THE EVENING...AND HAVE USED A LONGER-TERM 12 HOUR MOTION OF

035/07 KT FOR THIS ADVISORY. THE CYCLONE LIES BETWEEN A NORTHEAST

TO SOUTHWEST ORIENTED DEEP-LAYER RIDGE TO THE SOUTHEAST...AND AN

EAST TO WEST ORIENTED RIDGE CENTERED WELL TO THE WEST...NEAR

THE INTERNATIONAL DATE LINE. WATER VAPOR IMAGERY SHOWS A POTENT

MID-LATITUDE TROUGH MOVING QUICKLY EASTWARD TO THE NORTH OF

HAWAII...AND THIS TROUGH IS EXPECTED TO EXERT AN INCREASING

INFLUENCE ON OLAF THROUGH AT LEAST THE NEXT 48 HOURS...WITH THE

CYCLONE MOVING MORE QUICKLY TOWARD THE NORTHEAST. GUIDANCE DIVERGES

SIGNIFICANTLY AT 72 HOURS AND BEYOND...WITH THE GFS AND GFDL

CONTINUING TO ACCELERATE OLAF OFF TO THE NORTHEAST AS IT BECOMES

FULLY ENTRAINED IN THE MID-LATITUDE TROUGH...WHILE MOST OF THE OTHER

MODELS INCLUDING THE ECMWF TURN THE WEAKENING CYCLONE BACK TOWARD

THE SOUTHWEST...TO THE SOUTH OF A BUILDING DEEP-LAYER RIDGE OVER THE

NORTHEAST PACIFIC. THE GUIDANCE ENVELOPE DID SHIFT SIGNIFICANTLY

EASTWARD WITH THIS CYCLE. THE NEW OFFICIAL FORECAST REPRESENTS A

BLEND BETWEEN THE PREVIOUS TRACK AND THE TVCN MODEL CONSENSUS

THROUGH 48 HOURS...THEN IS MOST SIMILAR TO THE ECMWF AT 72 HOURS AND

BEYOND.



SATELLITE IMAGERY INDICATES THAT WEST/SOUTHWEST VERTICAL WIND SHEAR

CONTINUES TO IMPACT OLAF...WITH OUTFLOW RESTRICTED IN THOSE

QUADRANTS. UW-CIMSS AND SHIPS SHEAR MAGNITUDE ESTIMATES RANGE FROM

21 TO 27 KT...AND THE SHEAR SHOULD REMAIN ROUGHLY THE SAME OR

INCREASE SOMEWHAT DURING THE NEXT 48 HOURS AS THE MID-LATITUDE

TROUGH MOVES CLOSER TO THE CYCLONE. OLAF WILL ALSO BE MOVING OVER

COOLER SEA SURFACE TEMPERATURES AND DECREASING OCEAN HEAT CONTENT

VALUES DURING THE NEXT FEW DAYS. STEADY WEAKENING IS FORECAST. THE

OFFICIAL INTENSITY FORECAST IS CLOSE TO THE IVCN CONSENSUS...AND

REPRESENTS A COMPROMISE BETWEEN THE FASTER WEAKENING RATES DEPICTED

BY THE SHIPS AND LGEM...AND THE SLOWER RATES SHOWN BY MOST OF THE

DYNAMICAL MODELS. WE CONTINUE TO SHOW OLAF AS A POST-TROPICAL

REMNANT LOW AT DAYS 4 AND 5.





FORECAST POSITIONS AND MAX WINDS



INIT  25/0900Z 21.2N 143.8W   80 KT  90 MPH

 12H  25/1800Z 22.1N 143.2W   70 KT  80 MPH

 24H  26/0600Z 23.6N 141.9W   60 KT  70 MPH

 36H  26/1800Z 25.0N 140.0W   50 KT  60 MPH

 48H  27/0600Z 26.7N 137.5W   40 KT  45 MPH

 72H  28/0600Z 28.0N 134.0W   30 KT  35 MPH

 96H  29/0600Z 26.5N 133.5W   30 KT  35 MPH...POST-TROP/REMNT LOW

120H  30/0600Z 24.5N 140.0W   25 KT  30 MPH...POST-TROP/REMNT LOW



$$

FORECASTER JACOBSON