731 
 WTPA42 PHFO 240853
 TCDCP2
 
 HURRICANE IOKE DISCUSSION NUMBER  18
 NWS CENTRAL PACIFIC HURRICANE CENTER HONOLULU HI   CP012006
 1100 PM HST WED AUG 23 2006
 
 IOKE HAS BEEN INTENSIFYING THIS EVENING. INFRARED IMAGERY INDICATES
 THE EYE IS BECOMING WELL DEFINED AND THE CDO IS BECOMING MORE
 SYMMETRIC AROUND THE CENTER. THE T-NUMBERS FROM HFO...SAB...AND
 AFWA HAVE ALL INCREASED TO T5.5 AND JTWC HAS MAINTAINED A T5.0. THE
 INTENSITY HAS BEEN RAISED TO 100 KT FOR THIS ADVISORY...BRINGING
 IOKE BACK TO MAJOR HURRICANE STATUS /CATEGORY 3 ON THE SAFFIR-
 SIMPSON SCALE/ ONCE AGAIN.
 
 THE HURRICANE HAS BEEN MOVING NEAR 305/7 FOR THE PAST SIX HOURS...
 ALTHOUGH MORE RECENTLY THE MOTION APPEARS A BIT CLOSER TO DUE WEST.
 THE LONGWAVE TROUGH JUST WEST OF THE DATELINE HAS BEEN RETROGRADING
 WESTWARD...AND STRENGTHENING DEEP LAYER RIDGING NORTH OF THE CYCLONE
 IS EXPECTED TO CONTINUE STEERING IOKE ON A WEST-NORTHWEST COURSE
 THROUGH THE NEXT 24 TO 36 HOURS. THE MODELS...PARTICULARLY THE
 GFS...HAVE BEEN BACKING OFF ON THE INTENSIFICATION OF THE 
 SUBTROPICAL RIDGE TO THE NORTHWEST AND WEST OF IOKE IN THE LATER
 TIME PERIODS...AND THE GUIDANCE CONSENSUS HAS TRENDED A BIT MORE
 NORTHWARD IN RESPONSE. THE OFFICIAL FORECAST ALSO FOLLOWS THIS TREND.
 
 CONDITIONS CONTINUE TO APPEAR FAVORABLE FOR MODEST INTENSIFICATION
 IN THE SHORT TERM. SEA SURFACE TEMPERATURES REMAIN WARM ALONG THE
 FORECAST TRACK. SHEAR IS EXPECTED TO BE NEGLIGIBLE UNDERNEATH STRONG 
 UPPER LEVEL RIDGING...WHICH IS MOVING WESTWARD ROUGHLY IN TANDEM 
 WITH THE CYCLONE. 
 
 THE INTENSITY FORECAST BEYOND 36 HOURS BECOMES A BIT MORE 
 CHALLENGING. THE MODELS INDICATE THAT THE WESTWARD MOVING UPPER 
 RIDGE WILL START TO OUTRUN IOKE. AN UNSEASONABLY STRONG LONGWAVE
 TROUGH DIGGING SOUTHWARD BETWEEN THE MAIN HAWAIIAN ISLANDS AND IOKE
 IS EXPECTED TO INDUCE INCREASING NORTHERLY SHEAR AFTER 48 HOURS.
 HOWEVER...THE GLOBAL MODELS DIFFER IN THE AMOUNT OF SHEAR THAT IOKE
 WILL HAVE TO ENDURE...WITH THE GFS ON THE STRONGEST END OF THE
 GUIDANCE. THE FORECAST WEAKENING TREND IN THE LONGER RANGE REMAINS
 MORE MODEST THAN INDICATED BY THE SHIPS GUIDANCE AND MAINTAINS THAT
 IOKE WILL CROSS THE DATELINE INTO A THE WEST PACIFIC IN ABOUT 72
 HOURS AS A TYPHOON. NOTE THAT NAMED TROPICAL CYCLONES CROSSING INTO
 THE WEST PACIFIC BASIN MAINTAIN THEIR ORIGINAL NAME.
  
 FORECAST POSITIONS AND MAX WINDS
  
 INITIAL      24/0900Z 18.6N 172.3W   100 KT
  12HR VT     24/1800Z 19.0N 173.3W   100 KT
  24HR VT     25/0600Z 19.4N 174.4W   105 KT
  36HR VT     25/1800Z 19.6N 175.6W   105 KT
  48HR VT     26/0600Z 19.6N 177.1W   100 KT
  72HR VT     27/0600Z 19.1N 180.0E    90 KT
  96HR VT     28/0600Z 18.7N 176.8E    85 KT
 120HR VT     29/0600Z 18.5N 173.6E    70 KT
  
 $$
 FORECASTER R BALLARD