WTPA45 PHFO 251450

TCDCP5



HURRICANE OLAF DISCUSSION NUMBER  43

NWS CENTRAL PACIFIC HURRICANE CENTER HONOLULU HI   EP192015

500 AM HST SUN OCT 25 2015



OLAF CONTINUES TO HOLD ITS OWN...WITH INFRARED SATELLITE IMAGERY

SHOWING A RAGGED BUT PERSISTENT EYE DURING THE NIGHT. OVERALL

CONVECTIVE COVERAGE HAS DIMINISHED TO THE WEST AND SOUTH OF THE

CENTER...BUT THE CENTRAL CORE OF THE SYSTEM REMAINS INTACT AT THIS

TIME. SUBJECTIVE DVORAK CURRENT INTENSITY ESTIMATES REMAIN 4.5/77 KT

FROM ALL THREE AGENCIES...WHILE THE UW-CIMSS ADT CURRENT INTENSITY

ESTIMATE REMAINS MUCH STRONGER AT 5.5/102 KT. AN EARLIER ASCAT PASS

ACROSS THE WESTERN HALF OF THE CYCLONE DID FIND SOME HURRICANE FORCE

WIND BARBS...AND THE WIND RADII WERE ADJUSTED BASED ON THE ASCAT

DATA. THE INITIAL INTENSITY FOR THIS ADVISORY WILL REMAIN AT 80 KT.



OLAF HAS CONTINUED ON A STEADY NORTHEAST COURSE DURING THE NIGHT...

AND THE INITIAL MOTION ESTIMATE IS 035/07 KT. 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 NEW OFFICIAL FORECAST REPRESENTS A BLEND

BETWEEN THE PREVIOUS TRACK AND THE TVCN MODEL CONSENSUS THROUGH 48

HOURS...THEN IS NUDGED CLOSER TO THE ECMWF AT 72 HOURS AND BEYOND.



SATELLITE IMAGERY INDICATES THAT WESTERLY VERTICAL WIND SHEAR

CONTINUES TO IMPACT OLAF...WITH OUTFLOW RESTRICTED TO THE WEST

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

20 TO 28 KT...AND THE SHEAR IS FORECAST TO 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...AND MODEL OUTPUT AS WELL AS

SATELLITE DATA SUGGEST THAT THE CYCLONE WILL BE IMPACTED BY

SIGNIFICANT MID LEVEL DRY AIR. THE OFFICIAL INTENSITY FORECAST

REMAINS CLOSE TO THE IVCN CONSENSUS...AND SHOWS A SLOWER WEAKENING

TREND THAN PREVIOUSLY INDICATED DURING THE FIRST 24 HOURS DUE TO THE

RECENT RESILIENCE OF THE CYCLONE. THIS 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 DAY 4...

AND HAVE FORECAST DISSIPATION AT DAY 5.





FORECAST POSITIONS AND MAX WINDS



INIT  25/1500Z 21.6N 143.6W   80 KT  90 MPH

 12H  26/0000Z 22.8N 142.7W   75 KT  85 MPH

 24H  26/1200Z 24.5N 140.8W   65 KT  75 MPH

 36H  27/0000Z 26.2N 138.4W   50 KT  60 MPH

 48H  27/1200Z 28.1N 135.3W   40 KT  45 MPH

 72H  28/1200Z 29.0N 132.0W   30 KT  35 MPH

 96H  29/1200Z 25.5N 134.0W   30 KT  35 MPH...POST-TROP/REMNT LOW

120H  30/1200Z...DISSIPATED



$$

FORECASTER JACOBSON