WTPA42 PHFO 041446 TCDCP2 TROPICAL DEPRESSION ONE-C DISCUSSION NUMBER 4 NWS CENTRAL PACIFIC HURRICANE CENTER HONOLULU HI 5 AM HST THU AUG 04 2005 ONE-C HAS BECOME DIFFICULT TO LOCATE...WITH THE INITIAL POSITION REPRESENTING A COMPROMISE BETWEEN WHAT APPEARS TO BE A REMNANT MID-LEVEL CIRCULATION AND A POSSIBLE LLCC BEGINNING TO EMERGE FROM BENEATH HIGH CLOUDS A BIT FARTHER WEST. THE REMNANT MID-LEVEL CIRCULATION WAS THE FEATURE KEYED UPON FOR MOST SATELLITE FIXES. THE EMERGING LLCC IS A VERY RECENT DEVELOPMENT...OCCURRING WITHIN THE PAST HOUR OR SO. A SINGLE CB MARKS THE WESTERN FRINGE OF THIS LLCC. CONFIDENCE IS NOT YET HIGH ENOUGH TO SUDDENLY SWITCH THE INITIAL POSITION TO THIS NEW SUSPECTED FEATURE...HENCE THE COMPROMISE. ONCE AGAIN...TRACK GUIDANCE VARIES WIDELY...WITH DEEP LAYER GUIDANCE WANTING TO CURVE ONE-C TO THE NORTH LONG BEFORE REACHING THE ISLANDS. DEEP GUIDANCE WOULD ONLY BE USEFUL WITH A VIGOROUSLY CONVECTIVE ONE-C. UNTIL VIGOROUS AND PERSISTENT CONVECTION OCCURS...WE WILL USE SHALLOW-BASED GUIDANCE WHICH IS CONSIDERABLY FURTHER TO THE LEFT. THE OFFICIAL TRACK REMAINS VERY CLOSE TO THE LAST ONE...JUST TO THE RIGHT OF GFDL. THIS WILL TAKE ONE-C COMFORTABLY SOUTH OF THE MAIN HAWAIIAN ISLANDS. SINCE THE PREVIOUS FORECAST FOR STRENGTHENING ONE-C TO TROPICAL STORM THRESHOLD WAS BASED ON AN ANTICIPATED UPSURGE OF CONVECTION OVERNIGHT...THE CURRENT FORECAST NOW MAXES ONE-C AT ONLY 30 KT FROM 12 THROUGH 48 HOURS OUT. THIS IS IN LINE WITH MOST INTENSITY GUIDANCE...ALTHOUGH GFDL WANTS TO SUDDENLY STRENGTHEN ONE-C TO 40 KTS RIGHT AT 72 HOURS AFTER GRADUAL WEAKENING TO 19 KTS AT 48 HOURS. WE ANTICIPATE A SLOW DISSIPATION OF ONE-C THROUGH 120 HOURS...WITH LOW LEVEL TRADES PROVIDING PRIMARY STEERING. FORECASTER POWELL FORECAST POSITIONS AND MAX WINDS INITIAL 04/1500Z 15.2N 143.0W 25 KT 12HR VT 05/0000Z 15.5N 144.5W 30 KT 24HR VT 05/1200Z 15.6N 146.8W 30 KT 36HR VT 06/0000Z 15.6N 149.3W 30 KT 48HR VT 06/1200Z 15.6N 152.0W 30 KT 72HR VT 07/1200Z 15.5N 157.4W 25 KT 96HR VT 08/1200Z 14.9N 162.8W 20 KT...DISSIPATING 120HR VT 09/1200Z 14.2N 168.0W 15 KT...REMNANT LOW $$