WTPA42 PHFO 242050
TCDCP2

HURRICANE IOKE DISCUSSION NUMBER  20
NWS CENTRAL PACIFIC HURRICANE CENTER HONOLULU HI   CP012006
1100 AM HST THU AUG 24 2006

IOKE HAS INTENSIFIED CONSIDERABLY OVER THE PAST SEVERAL HOURS AND
ESPECIALLY COMPARED TO 24 HOURS AGO.  FIRST VISIBLE IMAGES OF THE
DAY SHOW A NICE SYMMETRIC HURRICANE WITH A 20 NM WIDE EYE AND
EYEWALL CONVECTION WRAPPING COMPLETELY AROUND.  THE SSMI PASS FROM
1726 UTC ALSO INDICATED A CLOSED EYEWALL.  DVORAK ESTIMATES FROM
CPHC...AFWA...JTWC AND SAB ALL INDICATE 127 KT SO THE INITIAL
INTENSITY HAS BEEN RAISED TO 125 KT...OR CATEGORY 4 ON THE
SAFFIR-SIMPSON SCALE.  

THE INITIAL MOTION IS 290 AT 6 KT AS IOKE PASSES SOUTH OF A
SUBTROPICAL RIDGE.  A LOW PRESSURE SYSTEM WEST OF THE DATELINE IS
RETREATING NORTHWESTWARD AND WILL BE REPLACED BY A NORTHEAST TO
SOUTHWEST ORIENTED RIDGE.  THE RIDGE IS EXPECTED TO SHIFT WESTWARD
AHEAD OF IOKE AND IMPART A SOUTHWESTWARD MOTION ON THE HURRICANE
FROM DAYS 2 THROUGH 4.  A WEAKNESS IN THE RIDGE ALONG WITH A
DEEPENING TROUGH IN THE NORTHWEST PACIFIC SHOULD PULL IOKE BACK ON
A NORTHWESTWARD TRACK BY DAY 5.  THE GLOBAL MODELS ARE IN GENERAL
AGREEMENT WITH THIS SCENARIO AND THE DYNAMIC OBJECTIVE AIDS ARE
CLUSTERED RATHER TIGHTLY THROUGH DAY 5.  THE FORECAST IS A BIT SOUTH
OF THE DYNAMIC CONSENSUS AND SLIGHT NORTH OF THE PREVIOUS TRACK
THROUGH DAY 2...THEN CLOSELY FOLLOWS THE CLUSTER OF DYNAMIC
GUIDANCE TRACKS FROM DAYS 2 THROUGH 5.

CONSIDERABLE CHANGES HAVE BEEN MADE TO THE INTENSITY FORECAST BOTH
IN THE NEAR TERM DUE TO THE INTENSIFICATION OF IOKE AND ESPECIALLY
OUT TO DAY 5.  SST VALUES ARE NEARLY 28C AND THE FORECAST TRACK
WILL TAKE THE HURRICANE OVER 29C WATERS SO THIS ASPECT FAVORS
SYSTEM MAINTENANCE OR EVEN FURTHER INTENSIFICATION.  THE 1800 UTC
CIMSS SHEAR ANALYSIS INDICATES ONLY 1.0 M/S VERTICAL SHEAR AND THE
NEAR TERM SHEAR VALUES SHOULD REMAIN LOW.  AS THE RIDGE
STRENGTHENS...IT IS EXPECTED THAT SOME DEGREE OF NORTHERLY TO
NORTHEASTERLY SHEAR FROM 48 HOURS WILL INDUCE SOME MODEST
WEAKENING.  OBJECTIVE INTENSITY GUIDANCE FAVORS KEEPING IOKE AT
LEAST AT CATEGORY 3 LEVELS THOUGH THE GFDI WANTS TO INCREASE IT TO
CATEGORY 5 AFTER 48 HOURS.  A HURRICANE OF THIS INTENSITY IS
EXPECTED TO HAVE RAPID AND TOUGH TO FORECAST FLUCTUATIONS IN
INTENSITY BUT THE FORECAST CALLS FOR MAINTAINING IOKE AT CURRENT
LEVELS THROUGH 36 HOURS.  SLIGHT WEAKENING TO 115 KT FROM SOME
SHEAR EFFECTS IS FORECAST AFTER 48 HOURS. IN SUMMARY...MAJOR
HURRICANE STATUS ALL THE WAY.
 
FORECAST POSITIONS AND MAX WINDS
 
INITIAL      24/2100Z 18.8N 173.3W   125 KT
 12HR VT     25/0600Z 19.2N 174.3W   125 KT
 24HR VT     25/1800Z 19.6N 175.6W   125 KT
 36HR VT     26/0600Z 19.7N 177.0W   125 KT
 48HR VT     26/1800Z 19.6N 178.4W   120 KT
 72HR VT     27/1800Z 18.7N 179.0E   115 KT
 96HR VT     28/1800Z 18.9N 176.3E   115 KT
120HR VT     29/1800Z 20.1N 174.0E   115 KT
 
$$
FORECASTER KODAMA