WDPN32 PGTW 171500 MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI// SUBJ/PROGNOSTIC REASONING FOR TYPHOON 29W (CHAMPI) WARNING NR 013// RMKS/ 1. FOR METEOROLOGISTS. 2. 6 HOUR SUMMARY AND ANALYSIS. SUMMARY: INITIAL POSITION: 12.6N 146.1E INITIAL INTENSITY: 120 KTS GEOGRAPHIC REFERENCE: 96 NM SOUTHEAST OF ANDERSEN AFB MOVEMENT PAST 6 HOURS: WESTWARD AT 12 KTS SIGNIFICANT WAVE HEIGHT: 42 FEET SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION: THE OVERALL STRUCTURE OF TY 29W IN ANIMATED ENHANCED INFRARED (EIR) SATELLITE IMAGERY HAS DETERIORATED OVER THE PAST SIX HOURS, AS THE THE PREVIOUSLY CLOUD-FREE, PINHOLE EYE HAS FILLED IN DUE TO AN ONGOING EYEWALL REPLACEMENT CYCLE (ERC). THE EYE REMAINS DETECTABLE IN EIR IMAGERY, AND APPEARS TO BE SLIGHTLY LARGER THAN SIX HOURS AGO. HOWEVER, THE EYE TEMPERATURES ARE VERY COLD (APPROXIMATELY -50C). ANIMATED RADAR IMAGERY FROM GUAM SHOWS THAT THE EYE TOOK A A TEMPORARY WEST-SOUTHWESTWARD TROCHOIDAL JOG OVER THE PAST SIX HOURS; HOWEVER, THE INTEGRATED MOTION VECTOR REMAINS STABLE AT 280 DEGREES AT 14 KNOTS BASED ON THE BEST TRACK. OVER THE PAST TWO HOURS, THE SYSTEM HAS RESUMED A WEST-NORTHWESTWARD HEADING AMID TROCHOIDAL OSCILLATION. RADAR DATA CLEARLY RESOLVES A CONCENTRIC EYEWALL MORPHOLOGY, HIGHLIGHTED BY A THICKENING INNER EYEWALL, A DISTINCT RADAR MOAT, AND A SECONDARY OUTER EYEWALL SITUATED APPROXIMATELY 30 NM DISTANT FROM THE GEOMETRIC CENTER-STRONG STRUCTURAL SIGNATURES CONFIRMING ERC PROGRESSION. THE INITIAL POSITION IS ASSESSED WITH HIGH CONFIDENCE BASED ON THE RADAR EYE FIXES. THE INITIAL INTENSITY IS ASSESSED WITH MEDIUM CONFIDENCE. ALTHOUGH THE EYE HAS FILLED WITHIN THE PAST TWO HOURS, THE SYSTEM LIKELY ATTAINED PEAK INTENSITY IMMEDIATELY PRIOR TO ERC INITIATION, WITH SURFACE WIND ENERGETICS TEMPORARILY LAGGING THE STRUCTURAL EVOLUTION. THIS IS REINFORCED BY CONCURRENT SUBJECTIVE AND OBJECTIVE SATELLITE ESTIMATES, WHICH CONVERGE AT 120 KNOTS. THE ENVIRONMENT REMAINS HIGHLY CONDUCIVE INDEPENDENT OF CORE-SCALE ERC DYNAMICS, SUPPORTED BY LOW DEEP-LAYER VWS, EXTREMELY WARM SSTS (29- 30C), AND VIGOROUS RADIAL OUTFLOW ALOFT. INITIAL WIND RADII BASIS: PERSISTENCE CURRENT STEERING MECHANISM: SOUTHERN PERIPHERY OF A DEEP-LAYER SUBTROPICAL RIDGE (STR) FAR TO THE NORTH. AGENCY DVORAK AND AUTOMATED FIXES: PGTW: T6.5 - 127 KTS RJTD: T6.0 - 115 KTS CIMSS ADT: 112 KTS AT 171130Z CIMSS AIDT: 122 KTS AT 171130Z CIMSS D-MINT: 120 KTS AT 171033Z CIMSS D-PRINT: 122 KTS AT 171130Z FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: HIGHLY FAVORABLE VWS: 10-15 KTS SST: 29-30 CELSIUS OUTFLOW: STRONG RADIAL OTHER FACTORS: EQUATORWARD OUTFLOW CHANNEL; EYEWALL REPLACEMENT CYCLE (ERC). ANALYSIS CONFIDENCE: INITIAL POSITION: HIGH INITIAL INTENSITY: MEDIUM INITIAL WIND RADII: LOW 3. FORECAST REASONING. SIGNIFICANT FORECAST CHANGES: THERE ARE NO SIGNIFICANT CHANGES TO THE FORECAST FROM THE PREVIOUS WARNING. FORECAST DISCUSSION: TYPHOON (TY) 29W IS TRACKING WESTWARD IN THE AGGREGATE, ALTHOUGH ERRATIC TROCHOIDAL MOTION IS PROJECTED TO PERSIST PENDING COMPLETION OF THE ERC. THE EXACT FREQUENCY AND AMPLITUDE OF THIS MOTION, WHICH REMAIN HIGHLY UNCERTAIN, WILL GOVERN THE PRECISE CPA AND TRACK GEOMETRY WHEN PASSING GUAM. THE CYCLONE WILL TRANSIT THE SOUTHERN TIP OF GUAM WITHIN THE NEXT SIX TO EIGHT HOURS. THE CORE WILL THEN VEER PROGRESSIVELY NORTHWESTWARD AS THE STR TO THE NORTH SLIDES EASTWARD, REPLACED BY A SECONDARY HIGH-PRESSURE CELL TRANSLATING RAPIDLY WEST-TO-EAST TO THE NORTH. BY TAU 96, THE STR WILL POSITION SOUTHEAST OF HONSHU, DEVELOPING A BROAD WEAKNESS OVER THE EAST CHINA SEA. CONSEQUENTLY, TY 29W WILL DECELERATE SHARPLY WHILE MAINTAINING A GENERAL NORTHWESTWARD HEADING PAST TAU 96 AS THE STEERING GRADIENT RELAXES. REGARDING INTENSITY: THE ACTIVE ERC INTRODUCES COMPETING THERMODYNAMIC AND STRUCTURAL INFLUENCES. SPECIFICALLY, THE DURATION OF THE EYEWALL REORGANIZATION AND THE TIMING OF NEW EYE EMERGENCE. HAFS-A PROJECTS NEW EYE STABILIZATION PRIOR TO THE CYCLONE CROSSING THE LONGITUDE OF GUAM, WHEREAS THE HWRF DELAYS ERC COMPLETION, UNTIL POST- PASSAGE BY GUAM. THE JTWC FORECAST FAVORS THE HWRF SCENARIO, PROJECTING THE CORE INTENSITY TO STABILIZE OR DECAY SLIGHTLY IN THE NEAR-TERM, FOLLOWED BY RE-INTENSIFICATION ONSET BY TAU 12. BY TAU 24, 29W IS PROJECTED TO RE-ATTAIN SUPER TYPHOON INTENSITY, PROGRESSING TO A PEAK OF 140 KNOTS BY TAU 36. AFTER TAU 36, HAFS-A PROJECTS MULTIPLE ERC EXTENDING THROUGH TAU 72; HOWEVER, THE TIMING AND PERIODICITY REMAIN HIGHLY UNCERTAIN. THE FORECAST HOLDS INTENSITY STABLE AT 13T KNOTS DURING THIS TIMEFRAME, ALTHOUGH SHORT-TERM STRUCTURAL FLUCTUATIONS OCCURRING ABOVE AND BELOW THIS MEAN ARE PROBABLE. POST- TAU 96, 29W WILL ENCOUNTER PROGRESSIVELY LOWER SSTS, EXACERBATED BY SELF-INDUCED COLD WATER UPWELLING AMID DECREASING TRANSLATION SPEEDS, INITIATING A GRADUAL DECAY THROUGH THE BALANCE OF THE FORECAST. MODEL DISCUSSION: TRACK GUIDANCE REMAINS IN EXCELLENT AGREEMENT THROUGHOUT THE FORECAST PERIOD. CROSS-TRACK SPREAD AT THE GUAM CPA IS CONFINED TO LESS THAN 20 NM. THE ENVELOPE GRADUALLY EXPANDS TO 180 NM BY TAU 120, BOUNDED EQUATORWARD BY NAVGEM AND POLEWARD BY THE GFS. THE JTWC FORECAST HEAVILY FAVORS THE AI CONSENSUS (AICN) MEAN WITH HIGH CONFIDENCE. SHORT-TERM TROCHOIDAL CORE OSCILLATION WILL INFLUENCE SPECIFIC CPA VALUES AT GUAM. ADDITIONALLY, AS THE ERC COMPLETES ITS CYCLE, THE INTENSE WIND FIELD RADII (34-KT, 50-KT, AND 64-KT SECTORS) WILL EXPAND. INTENSITY GUIDANCE EXHIBITS SOLID CONGRUENCE. DEEPMIND, CTCX, AND HWRF DEPICT AN INTENSITY PLATEAU THROUGH TAU 12, COINCIDENT WITH THE ERC, FOLLOWED BY RE-INTENSIFICATION PEAKING NEAR TAU 36. PROJECTED PEAKS SPREAD BETWEEN 130 KNOTS (CTCX) AND 150 KNOTS (DEEPMIND). THE MAJORITY OF THE SUITE PROJECTS A FLAT INTENSITY REGIME BETWEEN TAUS 36 AND 72, WITH WEAKENING POST-TAU 96. THE JTWC INTENSITY FORECAST ALIGNS WITH CTCX THROUGH TAU 12, THE FOLLOWING THE BROAD SHAPE OF HAFS-A THROUGH THE REMAINDER OF THE FORECAST. FORECAST CONFIDENCE: TRACK 00-72 HR: HIGH TRACK 72-120 HR: MEDIUM INTENSITY 00-72 HR: MEDIUM INTENSITY 72-120 HR: LOW// NNNN