WDPN31 PGTW 092100 MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI// SUBJ/PROGNOSTIC REASONING FOR TYPHOON 09W (BAVI) WARNING NR 036// RMKS/ 1. FOR METEOROLOGISTS. 2. 6 HOUR SUMMARY AND ANALYSIS. SUMMARY: INITIAL POSITION: 20.1N 128.2E INITIAL INTENSITY: 90 KTS GEOGRAPHIC REFERENCE: 385 NM SOUTH OF KADENA AB MOVEMENT PAST 6 HOURS: NORTH-NORTHWESTWARD AT 11 KTS SIGNIFICANT WAVE HEIGHT: 50 FEET SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION: ANIMATED ENHANCED INFRARED (EIR) SATELLITE IMAGERY SHOWS THAT TYPHOON 09W (BAVI) HAS SPENT MOST OF THE PAST SIX HOURS WITH A NEARLY HOLLOWED OUT INNER CORE, CONSISTING OF A PARTIAL INNER EYEWALL AND A NEAR TOTAL ABSENCE OF DEEP CONVECTION IN THE NORTHERN SEMICIRCLE. DURING THE PAST 2 HOURS, DEEP CONVECTION HAS REBUILT OVER THE CENTER AND BEGUN EXPANDING IN COVERAGE, BUT AN 091703Z AMSR-2 MICROWAVE PASS SHOWED ONLY A SOUTHEASTERN EYEWALL FRAGMENT PRESENT. AN EARLIER 0929Z SAR PASS SHOWED CONCENTRIC MAX WIND RINGS OF ABOUT 20 NM AND 55 NM RADII, RESPECTIVELY, WHICH AT THE TIME INDICATED A STALLING IN THE PROGRESS OF THE EYEWALL REPLACEMENT CYCLE (ERC) THAT HAS BEEN ONGOING FOR AT LEAST 24 HOURS. THE AFOREMENTIONED AMSR-2 PASS NOW SHOWS THE OUTER CONCENTRIC CONVECTIVE RING CLOSER TO 80 NM RADIUS, SUGGESTING THE ERC PROCESS REMAINS STALLED. INDEED, IN TERMS OF DEEP CONVECTION, A SECONDARY EYEWALL CAN BARELY BE SAID TO EXIST PRESENTLY. ABSENT SIGNIFICANT ENVIRONMENTAL SHEAR OR DRY AIR, THE RECENT SATELLITE PRESENTATION SUGGESTS DYNAMIC OCEANIC COOLING BENEATH THE STORM'S MASSIVE WIND FIELD MAY BE STABILIZING THE ENVIRONMENT AND REDUCING CONVECTIVE COVERAGE, PERHAPS ACCENTUATED BY A SHORT-TERM SLOWING OF THE STORM'S FORWARD MOTION BETWEEN 090600Z AND 091200Z, BUT NO REAL-TIME OCEAN MEASUREMENTS ARE AVAILABLE TO CONFIRM THIS. INITIAL WIND RADII BASIS: PERSISTENCE CURRENT STEERING MECHANISM: STR SOUTH OF JAPAN AGENCY DVORAK AND AUTOMATED FIXES: PGTW: T4.5 - 77 KTS RJTD: T5.0 - 90 KTS RCTP: T4.5 - 77 KTS KNES: T5.0 - 90 KTS CIMSS SATCON: 91 KTS AT 091200Z CIMSS ADT: 74 KTS AT 091800Z CIMSS AIDT: 76 KTS AT 091800Z CIMSS D-MINT: 99 KTS AT 090859Z CIMSS D-PRINT: 77 KTS AT 091800Z FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: FAVORABLE VWS: 5-10 KTS SST: 29-30 CELSIUS OUTFLOW: MODERATE RADIAL ANALYSIS CONFIDENCE: INITIAL POSITION: MEDIUM INITIAL INTENSITY: MEDIUM INITIAL WIND RADII: MEDIUM 3. FORECAST REASONING. SIGNIFICANT FORECAST CHANGES: THERE ARE NO SIGNIFICANT CHANGES TO THE FORECAST FROM THE PREVIOUS WARNING. FORECAST DISCUSSION: TYPHOON 09W (BAVI) IS CLEARLY STRUGGLING, LIKELY DUE TO ITS BROADENED CORE WIND FIELD ASSOCIATED WITH AN INCOMPLETE EYEWALL REPLACEMENT CYCLE (ERC) COMBINED WITH DYNAMIC OCEAN COOLING BENEATH THE STORM. THE SHORT-TERM INTENSITY FORECAST IS THUS AGAIN NUDGED LOWER RELATIVE TO THE LAST ONE, HOLDING BAVI AROUND 85 KT THROUGH LANDFALL IN EASTERN CHINA JUST BEFORE 48 HOURS, CLOSE TO A BLEND OF THE OCEAN-COUPLED HAFS-A AND HWRF MODELS AND THE EXPERIMENTAL GOOGLE DEEPMIND ENSEMBLE MEAN. SOME INTENSITY FLUCTUATIONS ARE POSSIBLE IF THE INNER CORE WIND FIELD TIGHTENS OR THE STORM MOVES OVER DIFFERENT OCEAN EDDIES, BUT MODELS HAVE MARKEDLY DECREASED THEIR STEADY STATE INTENSITY PREDICTION RELATIVE TO A DAY AGO. BAVI'S NORTHWESTWARD MOTION AROUND THE SUBTROPICAL RIDGE NEAR JAPAN WILL CARRY IT NEAR ISHIGAKIJIMA IN AROUND 24 HOURS, THEN THROUGH THE EAST CHINA SEA TO THE NORTH OF TAIWAN, THEN INLAND OVER EASTERN CHINA. THE STORM WILL LIKELY DISSIPATE INLAND BY 96 HOURS AS IT TURNS NORTHWARD, THOUGH A BELT OF ELEVATED WINDS ASSOCIATED WITH THE REMNANT CIRCULATION MAY CONTINUE MARCHING NORTHWARD UP THE CHINESE COASTLINE. MODEL DISCUSSION: THE JTWC TRACK FORECAST IS PLACED WITH HIGH CONFIDENCE NEAR A BLEND OF THE PHYSICS-BASED MODEL CONSENSUS, WHICH MAKES UP THE LEFT EDGE OF THE GUIDANCE ENVELOPE, AND THE AI-BASED MODEL CONSENSUS, WHICH MAKES UP THE RIGHT EDGE OF THE GUIDANCE ENVELOPE. THE JTWC INTENSITY FORECAST IS CLOSE TO A BLEND OF THE OCEAN-COUPLED HAFS-A AND HWRF MODELS AND THE EXPERIMENTAL GOOGLE DEEPMIND ENSEMBLE, PLACED WITH MEDIUM CONFIDENCE. FORECAST CONFIDENCE: TRACK 00-72 HR: HIGH TRACK 72-120 HR: HIGH INTENSITY 00-72 HR: MEDIUM INTENSITY 72-120 HR: MEDIUM// NNNN