WTPA45 PHFO 240257

TCDCP5



HURRICANE OLAF DISCUSSION NUMBER  37

NWS CENTRAL PACIFIC HURRICANE CENTER HONOLULU HI   EP192015

500 PM HST FRI OCT 23 2015



THE OVERALL SATELLITE PRESENTATION OF OLAF HAS CHANGED LITTLE SINCE

THE PREVIOUS ADVISORY. SIMILAR TO THIS MORNING...STRONG EYE WALL

CONVECTION CONTINUES TO ROTATE AROUND THE CENTER...WITH BREAKS IN

THE EYE WALL HIGHLIGHTED BY BOTH CONVENTIONAL AND MICROWAVE

IMAGERY. WATER VAPOR IMAGERY SHOWS OUTFLOW BECOMING INCREASINGLY

RESTRICTED IN THE SOUTH AND SOUTHWEST SEMICIRCLES DUE TO

SOUTHWESTERLY SHEAR NEAR 20 KT...WHILE A MID- AND UPPER-LEVEL

SHORTWAVE TROUGH PASSING NORTH OF OLAF APPEARS TO HAVE ENHANCED

OUTFLOW IN THE NORTHERN SEMICIRCLE. SUBJECTIVE DVORAK CURRENT

INTENSITY ESTIMATES FROM PHFO/SAB/PGTW ARE ONCE AGAIN A CONSENSUS

5.5/102 KT...WHILE SATCON FROM UW-CIMSS INDICATED AN INTENSITY NEAR

110 KT. BASED ON THIS DATA...THE INITIAL INTENSITY FOR THIS ADVISORY

HAS BEEN MAINTAINED AT 105 KT.



THE RAGGED AND CLOUD-FILLED EYE OF OLAF HAS BEEN WOBBLING

SIGNIFICANTLY OVER THE PAST 6 TO 12 HOURS AS IT MOVES GENERALLY

NORTHWARD...AND SMOOTHING OUT THE WOBBLES YIELDS AN INITIAL MOTION

OF 015/09 KT FOR THIS ADVISORY. OVERALL TRACK FORECAST PHILOSOPHY

REMAINS GENERALLY THE SAME HAS BEEN RECENTLY PRESENTED...BUT

GLOBAL MODELS HAVE BEEN TRENDING TOWARD A WEAKER STEERING FLOW AND

A SLOWER FORECAST FORWARD MOTION. GENERALLY SPEAKING...OLAF IS

FORECAST TO TRACK TOWARD THE NORTH-NORTHEAST THROUGH DAY 4...WITH

INCREASED UNCERTAINTY SURROUNDING THE DAY 5 POSITION AND MOTION.



THE CURRENT SYNOPTIC SETUP FEATURES A MID-LEVEL HIGH CENTERED EAST

OF OLAF...WITH ANOTHER MID-LEVEL HIGH CENTERED JUST WEST OF THE DATE

LINE. THE RIDGE ASSOCIATED WITH THE DATE LINE HIGH EXTENDS EASTWARD

TO NEAR THE HAWAIIAN ISLANDS...WHILE A SIGNIFICANT BREAK IN THE

RIDGE EXISTS NORTH OF OLAF. SHORTWAVE TROUGHS EMBEDDED IN THE

MID-LATITUDE WESTERLIES ARE MAINTAINING THE BREAK IN THE

RIDGE...WITH A FAST-MOVING TROUGH CURRENTLY PASSING NORTH OF OLAF.

THIS TROUGH IS FORECAST TO LIFT RAPIDLY NORTHEASTWARD OVER THE NEXT

12 TO 24 HOURS...AND THE PRIMARY STEERING FEATURE WILL THEN BECOME

THE HIGH EAST OF OLAF...WHICH WILL MOVE TO A POSITION SOUTHEAST...

AND THEN SOUTH...OF OLAF THROUGH THE WEEKEND. ANOTHER SHORTWAVE

PASSING NORTH OF OLAF OVER THE WEEKEND WAS EARLIER FORECAST TO DIG

FURTHER SOUTHEAST THAN RECENT GUIDANCE SUGGESTS. WITH THIS TROUGH

NOW EXPECTED TO BE FARTHER NORTH...THE PRIMARY STEERING MECHANISM

WILL BE THE RIDGE SOUTH OF OLAF. THE TRACK FORECAST AND GUIDANCE HAS

RESPONDED BY SLOWING THE FORWARD SPEED OF OLAF...ESPECIALLY IN THE 3

TO 5 DAY RANGE. AT THE END OF THE FORECAST PERIOD...THE RIDGE

CURRENTLY NEAR THE DATE LINE IS EXPECTED TO SHIFT RAPIDLY EASTWARD

AND BUILD NORTH OF OLAF. GLOBAL MODELS INDICATE THAT THIS WILL CAUSE

OLAF TO BRIEFLY BECOME NEARLY STATIONARY...BEFORE MAKING A TURN BACK

TOWARD THE WEST. THE UPDATED OFFICIAL FORECAST INDICATES VERY LITTLE

CHANGE IN FORECAST POSITIONS BETWEEN DAYS 4 AND 5 AS THIS OCCURS.

OTHERWISE...THE UPDATED TRACK FORECAST LIES CLOSE TO THE

PREVIOUS...AND CLOSELY FOLLOWS THE TVCN AND FSSE GUIDANCE...BUT IS

NOT AS FAST IN TURNING OLAF BACK TOWARD THE WEST ON DAY 5.



THE FORECAST TRACK TAKES OLAF OVER STEADILY DECREASING SSTS...WITH

VALUES EXPECTED TO DIMINISH FROM JUST BELOW 28C CURRENTLY...TO NEAR

25C BY DAY 5. VERTICAL SHEAR IS FORECAST TO INCREASE OVER THE NEXT

12 HOURS...AS THE AFOREMENTIONED SHORTWAVE PASSES NORTH OF OLAF...

AND THEN FLUCTUATE THROUGH THE REMAINDER OF THE FORECAST PERIOD AS

A DYNAMIC PATTERN ALOFT DEVELOPS. DESPITE RECENT TRENDS OF

MAINTAINING STRENGTH...FAIRLY STEADY WEAKENING IS ANTICIPATED

THROUGH THE FORECAST PERIOD. THE UPDATED INTENSITY FORECAST

REPRESENTS A BLEND OF THE PREVIOUS AND THE INTENSITY CONSENSUS

IVCN...BUT REMAINS HIGHER THAN MOST OF THE GUIDANCE...INCLUDING

SHIPS...WHICH INDICATES DISSIPATION AFTER 72 HOURS.



A WELL-PLACED ASCAT PASS AROUND 1920Z WAS UTILIZED TO FINE-TUNE THE

34 AND 50 KT WIND RADII...WITH THE PRIMARY EFFECT BEING AN

EXPANSION OF THE RADII...ESPECIALLY IN THE SOUTH SEMICIRCLE.





FORECAST POSITIONS AND MAX WINDS



INIT  24/0300Z 18.2N 145.8W  105 KT 120 MPH

 12H  24/1200Z 19.0N 145.4W   95 KT 110 MPH

 24H  25/0000Z 20.2N 144.9W   80 KT  90 MPH

 36H  25/1200Z 21.3N 144.3W   70 KT  80 MPH

 48H  26/0000Z 22.2N 143.7W   60 KT  70 MPH

 72H  27/0000Z 24.0N 141.7W   50 KT  60 MPH

 96H  28/0000Z 25.5N 139.5W   40 KT  45 MPH

120H  29/0000Z 26.0N 139.5W   30 KT  35 MPH



$$



FORECASTER BIRCHARD