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 073 
 WTPA45 PHFO 210917 CCA
 TCDCP5
 
 HURRICANE OLAF DISCUSSION NUMBER  26...CORRECTED
 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 
 OF 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
 
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