311 
 WTPA45 PHFO 110851 CCA
 TCDCP5
 
 HURRICANE HILDA DISCUSSION NUMBER  22
 NWS CENTRAL PACIFIC HURRICANE CENTER HONOLULU HI   EP102015
 1100 PM HST MON AUG 10 2015
  
 DATA COLLECTED BY U.S. 53RD WEATHER RECONNAISSANCE AIRCRAFT WERE 
 CRITICAL IN DETERMINING THE INITIAL INTENSITY AND WIND STRUCTURE OF 
 HILDA THIS EVENING. ALTHOUGH HILDA IS ENCOUNTERING A PROVERBIAL
 WALL OF SHEAR...WITH ANALYSES FROM UW-CIMSS INDICATING AROUND 35 KT
 OF SOUTHWESTERLY SHEAR...HILDA HAS THUS FAR BEEN ABLE TO MAINTAIN
 AN INNER CORE. MAXIMUM SFMR WINDS ON THE INITIAL PENETRATION WERE
 NEAR 80 KT...AND A REDUCTION OF MAXIMUM FLIGHT LEVEL WINDS YIELDS
 SURFACE WINDS 0F 77 KT...THUS THE INITIAL INTENSITY WILL BE
 MAINTAINED AT 80 KT FOR THIS ADVISORY. A 25 TO 30 NM WIDE EYE WAS
 NOTED BY THE FLIGHT CREW TO BE OPEN TO THE SOUTHWEST...WHICH WAS
 NICELY HIGHLIGHTED BY 0405Z SSMI/S AND 0411Z GPM MICROWAVE
 OVERPASSES. IN COORDINATION WITH CHIEF...AERIAL RECONNAISSANCE
 COORDINATION...ALL HURRICANES /CARCAH/...FLIGHTS INTO HILDA WILL
 BEGIN AT 6 HOURLY INTERVALS STARTING TUESDAY EVENING...WITH THE
 NEXT MISSION SLATED FOR TUESDAY MORNING.
 
 THE AIRCRAFT CENTER FIXES INDICATED THAT HILDA WAS MOVING VERY 
 SLOWLY...HAVING MOVED ABOUT 7 NM TOWARD THE NORTH-NORTHWEST IN 2 
 HOURS. A SLIGHTLY LONGER TERM INITIAL MOTION ESTIMATE FOR THIS 
 ADVISORY IS DETERMINED TO BE 315/04 KT. ALTHOUGH THE UPPER LEVEL 
 FLOW OVER HILDA FEATURES RELATIVELY STRONG WESTERLY WINDS...THE 
 CYCLONE IS CURRENTLY IN AN AREA OF LIGHT STEERING WINDS. 
 
 OVER THE NEXT 36 HOURS...HILDA IS FORECAST TO MOVE SLOWLY TOWARD
 THE NORTHWEST...STEERED BY THE WEAK CURRENTS BETWEEN A LOW ALOFT
 NORTH OF HAWAII...AND A HIGH TO THE DISTANT EAST. THIS WILL LEAD
 TO GRADUAL WEAKENING...DUE TO STRONG UPPER LEVEL WESTERLIES SHEARING
 AT LEAST THE UPPER PORTIONS OF THE CYCLONE NORTHEASTWARD. A TURN
 TOWARD THE WEST-NORTHWEST AND A SLIGHT ACCELERATION ARE EXPECTED
 THEREAFTER AS HILDA BECOMES INCREASINGLY SHALLOW AND THE VERTICAL
 STRUCTURE OF THE CYCLONE BECOMES INCREASINGLY COMPROMISED. THE 
 OFFICIAL TRACK AND INTENSITY FORECASTS FOR THIS PACKAGE CLOSELY 
 FOLLOW THE PREVIOUS...WITH THE TRACK PARALLELING THE TVCN 
 CONSENSUS...AND CLOSE TO THE LATEST HWRF GUIDANCE. AFTER ACCOUNTING 
 FOR THE INITIAL INTENSITY...THE OFFICIAL FORECAST CLOSELY FOLLOWS 
 THE PREVIOUS...AND IS CLOSE TO SHIPS GUIDANCE THROUGH 48 HOURS. THE 
 RATE OF WEAKENING THEREAFTER IS CLOSE TO THE IVCN CONSENSUS...AND 
 SLOWER THAN SHIPS GUIDANCE...BUT ANTICIPATES THAT HILDA WILL BECOME 
 A REMNANT LOW BY THE END OF THE FORECAST PERIOD.  
 
 ON THE FORECAST TRACK...A TROPICAL STORM WATCH MAY BE REQUIRED FOR 
 THE BIG ISLAND...POSSIBLY AS EARLY AS TUESDAY MORNING. UNCERTAINTY 
 REMAINS AS TO THE EVENTUAL IMPACTS THAT MAY BE FELT IN THE HAWAIIAN 
 ISLANDS FROM HILDA...BUT THE POTENTIAL FOR LARGE SURF AND VERY HEAVY
 RAINFALL APPEARS TO BE INCREASING. 
  
 
 FORECAST POSITIONS AND MAX WINDS
  
 INIT  11/0900Z 17.1N 150.9W   80 KT  90 MPH
  12H  11/1800Z 17.5N 151.3W   70 KT  80 MPH
  24H  12/0600Z 18.0N 152.0W   60 KT  70 MPH
  36H  12/1800Z 18.5N 152.7W   50 KT  60 MPH
  48H  13/0600Z 18.9N 153.7W   40 KT  45 MPH
  72H  14/0600Z 19.3N 156.0W   35 KT  40 MPH
  96H  15/0600Z 19.5N 158.5W   30 KT  35 MPH
 120H  16/0600Z 20.0N 161.0W   25 KT  30 MPH...POST-TROP/REMNT LOW
  
 $$
 
 FORECASTER BIRCHARD