WTPA42 PHFO 261505 TCDCP2 HURRICANE IOKE DISCUSSION NUMBER 27 NWS CENTRAL PACIFIC HURRICANE CENTER HONOLULU HI CP012006 500 AM HST SAT AUG 26 2006 HURRICANE IOKE IS ONCE AGAIN A CATEGORY 5 STORM...WITH SUBJECTIVE DVORAK ESTIMATES FOR 26/1130Z RANGING FROM 6.5 TO 7.0...OR 127 TO 140KT. 1130Z ADT ESTIMATE WAS 7.0. RECENT GOES INFRARED IMAGERY SHOWS CLOUD TOP TEMPS REACHING -79C WITH EYE TEMPS AT +9.9C. A VERY SYMMETRICAL RING OF -72 TO -75C CLOUD TOPS NOW SURROUNDS THE EYE. THAT SAID...HAVE INCREASED THE INITIAL INTENSITY TO 140 KT. ONCE AGAIN THE BIG ISSUE WITH THE TRACK GUIDANCE FOR THE 12Z MODEL SUITE IS THAT THE UKMET TRACK BOUNCED OFF THE DATE LINE...RESULTING IN AN ERRONEOUS MIRROR IMAGE TRACK...EASTBOUND BACK INTO THE CENTRAL PACIFIC. THIS THREW ALL OF THE CONSENSUS MODEL TRACKS OFF...BENDING THEM BACK SHARPLY EASTWARD. THAT SAID...HAVE BEEN FORCED TO IGNORE ALL CONSENSUS MODELS ONCE AGAIN...AND GO WITH A BLEND OF THE BAMM...BAMD...ECMWF...AND GFS. THE GFS SHOWS IOKE CONTINUING TO MOVE IN TANDEM WITH AN ANTICYCLONE LOCATED AROUND 25N UNTIL IT REACHES ABOUT 170E, THEN THE ANTICYCLONE STALLS IN RESPONSE TO A WELL DEVELOPED TROUGH NEAR 155E. IOKE THEN MOVES AROUND THE SOUTHWESTERN PERIPHERY OF THE ANTICYCLONE TO THE NORTH...AND BEGINS A CURVE TO THE NORTHWEST. THE 500 MB TREND OF THE GFS OVER THE LAST 3 RUNS HAS BEEN TO DIG THE TROUGH MORE DEEPLY AT 155E BY WED 30/18Z...HOWEVER THIS MAY NOT BE IN TIME TO KEEP THE STORM FROM BECOMING A SERIOUS THREAT TO WAKE ISLAND. THE NEW FORECAST TRACK IS VERY CLOSE TO THE PREVIOUS TRACK THROUGH 72 HOURS...WITH A SLIGHT MOVE TO THE NORTH TOWARD THE GFS SOLUTION AFTER THAT. THIS TRACK CONTINUES TO HAVE SERIOUS IMPLICATIONS FOR WAKE ISLAND IN THE 96 TO 120 HOUR TIME FRAME...WITH THE CURRENT FORECAST TRACK TAKING IT JUST NORTH OF THE ISLAND. IN THE SHORT TERM...THE INTENSITY FORECAST SHOWS A SLIGHT WEAKENING OVER THE NEXT 12 HOURS...PRIMARILY DUE TO THE SSMIS 91 GHZ IMAGE AT 1030Z WHICH SHOWED WELL DEVELOPED CONCENTRIC EYEWALLS...ONE WITH A RADIUS OF ABOUT 10 NM...AND ANOTHER OUT AT ABOUT 4O NM. THE INNER EYEWALL WILL LIKELY COLLAPSE SOMETIME OVER THE NEXT 24 HOURS... LEADING TO A TEMPORARY WEAKENING. THE CYCLE WILL LIKELY BE SIMILAR TO THAT SEEN OVER THE LAST 24 HOURS...SO THE INTENSITY WAS INCREASED ONCE AGAIN AT 24 HOURS. BEYOND THAT...IT WAS KEPT CONSTANT UNTIL RECURVATURE LATE IN THE FORECAST. LOOKING AT CURRENT ENVIRONMENTAL WIND FIELDS AROUND IOKE AND HOW THE STORM HAS RESPONDED..BY INTENSIFYING AGAIN TO A CATEGORY 5...THE STORM WILL LIKELY REMAIN A CATEGORY 4 OR 5 STORM FOR THE NEXT SEVERAL DAYS. EYEWALL REPLACEMENT CYCLES WILL LIKELY BRING PERIODIC FLUCTUATIONS IN INTENSITY...HOWEVER THERE IS NO CLEAR EVIDENCE FOR ANY SIGNIFICANT CHANGE IN THE OVERALL STORM ENVIRONMENT. ANOMALOUSLY STRONG MID AND UPPER LEVEL CYCLONES AT ABOUT 150W AND 155E FLANK A HUGE ANTICYCLONE COVERING THE MID PACIFIC...AND IOKE WILL LIKELY CONTINUE TO BENEFIT FROM THE RESULTING LOW SHEAR AND FAVORABLE OUTFLOW PATTERN. IN ADDITION...SST VALUES WARM TO 29C ALONG THE TRACK. IF INDEED IOKE MAINTAINS CATEGORY 4 OR 5 STATUS FOR THE NEXT 96 HOURS...A PRELIMINARY SURVEY OF THE RECORDS SHOW THAT THIS COULD BE A WORLD RECORD FOR LONGEVITY OF A CATEGORY 4 OR GREATER STORM. FORECAST POSITIONS AND MAX WINDS INITIAL 26/1500Z 18.7N 177.9W 140 KT 12HR VT 27/0000Z 18.3N 179.2W 135 KT 24HR VT 27/1200Z 17.8N 178.9E 140 KT 36HR VT 28/0000Z 17.4N 177.0E 140 KT 48HR VT 28/1200Z 17.2N 174.9E 140 KT 72HR VT 29/1200Z 17.2N 170.9E 140 KT 96HR VT 30/1200Z 18.9N 167.8E 135 KT 120HR VT 31/1200Z 21.7N 164.8E 130 KT $$ FORECASTER BROWNING