WTPA45 PHFO 210901

TCDCP5



HURRICANE OLAF DISCUSSION NUMBER  26

NWS CENTRAL PACIFIC HURRICANE CENTER HONOLULU HI   EP192015

1100 PM HST TUE OCT 20 2015



ALTHOUGH OLAF CONTINUES TO PRESENT A FAIRLY IMPRESSIVE SATELLITE

SIGNATURE THIS EVENING...THE OVERALL PRESENTATION HAS DEGRADED OVER

THE PAST 6 HOURS. THE EYE HAS BECOME INCREASINGLY CLOUD-FILLED WHILE

SURROUNDING CONVECTION IS NOT AS INTENSE AS IT ONCE WAS. THE OUTFLOW

PATTERN ALOFT IS STILL FAIRLY SYMMETRIC...EXCEPT FOR SOME LIMITED

OUTFLOW IN THE NORTHWEST QUADRANT. THE OBSERVED SATELLITE TRENDS LED

TO LOWERING DVORAK DATA-T VALUES...WHILE CURRENT INTENSITY ESTIMATES

RANGED FROM 5.5/102 KT FROM PGTW...TO 6.0/115 KT FROM PHFO AND

SAB...WITH UW-CIMSS SATCON INDICATING AN INTENSITY NEAR 110 KT. A

CONSERVATIVE BLEND OF THESE ESTIMATES LEADS TO AN INITIAL INTENSITY

FOR 115 KT FOR THIS ADVISORY.



THE INITIAL MOTION FOR THIS ADVISORY IS 300/08 KT...WITH OLAF

FINALLY MAKING THE EXPECTED TURN TOWARD THE WEST-NORTHWEST BEFORE

EVENTUALLY MOVING ON AN INCREASINGLY NORTHWARD VECTOR. A MID-LEVEL

RIDGE THAT HAD BEEN NORTH OF OLAF OVER THE PAST COUPLE OF DAYS IS

IN THE PROCESS OF WEAKENING AND SHIFTING SOUTHEASTWARD...WHICH IS

ALLOWING OLAF TO GAIN LATITUDE. ON WEDNESDAY AND THURSDAY THE

PATTERN WILL FEATURE A MID-LEVEL HIGH CENTERED EAST OF OLAF...

WITH A WEAKER MID-LEVEL RIDGE NORTH OF OLAF ASSOCIATED WITH A

HIGH CENTERED NEAR THE INTERNATIONAL DATE LINE. THIS IS EXPECTED TO

IMPART A STEERING MOTION TOWARD THE NORTHWEST AND THEN

NORTH-NORTHWEST...AS PASSING MID-LATITUDE SHORTWAVE TROUGHS TO

THE NORTH ENSURE THAT THE RIDGE NORTH OF OLAF REMAINS WEAK. A MORE

SIGNIFICANT BREAK IN THE RIDGE WILL BEGIN ON FRIDAY AND CONTINUE

INTO THE WEEKEND DUE TO A STRONGER SHORTWAVE TROUGH. OLAF IS

EXPECTED TO BECOME EMBEDDED IN THE MID-LATITUDE WESTERLIES BY THE

END OF THE FORECAST PERIOD...WHICH WILL STEER IT TOWARD THE

NORTHEAST.



THE TRACK GUIDANCE REMAINS TIGHTLY CLUSTERED OVER THE FIRST 3 TO 4

DAYS OF THE FORECAST...AND DIVERGES SOMEWHAT TOWARD THE END OF THE

FORECAST PERIOD AS OLAF BEGINS TO MOVE NORTHEASTWARD. THE UPDATED

FORECAST IS CLOSE TO THE PREVIOUS...AND THE RELIABLE MULTI-MODEL

CONSENSUS TVCN...BUT RIDES THE LEFT EDGE OF THE NARROW GUIDANCE

ENVELOPE THROUGH THE FIRST 72 HOURS. THE 96 AND 120 HOUR FORECAST

POSITIONS HAVE BEEN SHIFTED TO THE RIGHT OF THE PREVIOUS...TO BE IN

LINE WITH THE GFEX AND TVCN CONSENSUS...WHICH INDICATE A FASTER TURN

TOWARD THE NORTHEAST THAN PREVIOUSLY OFFICIALLY FORECAST.



LIGHT SHEAR AND SSTS BETWEEN 28C AND 29C OVER THE NEXT 24 TO 36

HOURS ARE EXPECTED TO LEAD TO LITTLE CHANGE IN OLAF/S INTENSITY.

INCREASING SHEAR AND GRADUALLY LOWERING SSTS WILL LEAD TO A GRADUAL

WEAKENING TREND FROM 48 TO 72 HOURS...WITH INCREASING SOUTHWESTERLY

SHEAR AND MORE RAPIDLY DIMINISHING SSTS THEREAFTER LEADING TO A MORE

RAPID WEAKENING. THE UPDATED FORECAST FOLLOWS TRENDS PRESENTED BY

THE PREVIOUS...AS WELL AS THE SHIPS...LGEM AND IVCN INTENSITY

CONSENSUS...AFTER ACCOUNTING FOR A LOWER THAN EXPECTED INITIAL

INTENSITY.





FORECAST POSITIONS AND MAX WINDS



INIT  21/0900Z 11.5N 143.8W  115 KT 135 MPH

 12H  21/1800Z 12.3N 144.7W  115 KT 135 MPH

 24H  22/0600Z 13.5N 145.8W  110 KT 125 MPH

 36H  22/1800Z 14.7N 146.5W  110 KT 125 MPH

 48H  23/0600Z 16.0N 146.9W  100 KT 115 MPH

 72H  24/0600Z 19.1N 147.0W   85 KT 100 MPH

 96H  25/0600Z 21.5N 145.5W   70 KT  80 MPH

120H  26/0600Z 24.0N 143.5W   55 KT  65 MPH



$$



FORECASTER BIRCHARD