WDPN31 PGTW 081500 MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI// SUBJ/PROGNOSTIC REASONING FOR TYPHOON 09W (BAVI) WARNING NR 031// RMKS/ 1. FOR METEOROLOGISTS. 2. 6 HOUR SUMMARY AND ANALYSIS. SUMMARY: INITIAL POSITION: 17.3N 131.8E INITIAL INTENSITY: 125 KTS GEOGRAPHIC REFERENCE: 595 NM SOUTH-SOUTHEAST OF KADENA AB MOVEMENT PAST 6 HOURS: WEST-NORTHWESTWARD AT 12 KTS SIGNIFICANT WAVE HEIGHT: 50 FEET SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION: ANIMATED ENHANCED INFRARED (EIR) SATELLITE IMAGERY DEPICTS TYPHOON 09W (BAVI) ATTEMPTING TO UNDERGO ANOTHER EYEWALL REPLACEMENT CYCLE (ERC) WITH CLEAR SEPARATION BETWEEN THE INNER-CORE AND A VERY LARGE SECONDARY EYEWALL, PARTICULARLY WITHIN THE NORTHERN SEMICIRCLE. IN RESPONSE TO THE ERC, THE OVERALL CONVECTIVE STRUCTURE HAS CLEARLY DEGRADED OVER THE PAST 6 HOURS AND HAS CAUSED A LOWERING IN INTENSITY. THE ERC WAS CAPTURED WELL BY THE 080913Z SSMIS 37 GHZ MICROWAVE IMAGE WHICH REVEALED A WIDE MOAT FEATURE SEPARATING THE TWO EYEWALLS. THE INNER EYEWALL DOES APPEAR TO BE RESTRUCTURING AT AROUND 081400Z, SUGGESTING THAT THE ERC MAY NOT BE ABLE TO ENTIRELY COMPLETE. A 080910Z RADARSAT-2 SAR IMAGE SHOWED A VMAX PEAK OF 126 KTS WITHIN THE NORTHERN PORTION OF THE EYEWALL AND AN R64 OF OVER 100 NM FROM THE CENTER IN ALL QUADRANTS. THE INITIAL INTENSITY OF 125 KTS IS ASSESSED WITH MEDIUM CONFIDENCE BASED ON THE SAR DATA ALONG WITH THE AGENCY DVORAK AND CIMSS INTENSITY ESTIMATES LISTED BELOW. THE INITIAL POSITION IS PLACED WITH HIGH CONFIDENCE BASED ON THE EYE IN ANIMATED EIR IMAGERY. ENVIRONMENTAL ANALYSIS INDICATES THAT 09W REMAINS IN A MARGINALLY FAVORABLE ENVIRONMENT CHARACTERIZED BY STRONG RADIAL OUTFLOW ALOFT AND WARM (29-30 C) SEA SURFACE TEMPERATURES OFFSET BY MODERATE TO HIGH (20-25 KTS) NORTHEASTERLY VERTICAL WIND SHEAR AND SLIGHT DRY AIR INTRUSION. INITIAL WIND RADII BASIS: 080910Z RADARSAT-2 SAR DATA CURRENT STEERING MECHANISM: A COMBINED STEERING INFLUENCE FROM THE WESTERN EXTENSION OF A SUBTROPICAL RIDGE (STR) POSITIONED TO THE NORTHEAST AND THE SOUTHWESTERN EXTENSION OF A SEPARATE STR CENTERED OVER SOUTHERN JAPAN. AGENCY DVORAK AND AUTOMATED FIXES: PGTW: T6.5 - 127 KTS RJTD: T6.5 - 127 KTS RCTP: T6.5 - 127 KTS KNES: T6.5 - 127 KTS CIMSS SATCON: 137 KTS AT 081200Z CIMSS ADT: 112 KTS AT 081200Z CIMSS AIDT: 114 KTS AT 081200Z CIMSS D-MINT: 136 KTS AT 080914Z CIMSS D-PRINT: 123 KTS AT 081200Z FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: MARGINALLY FAVORABLE VWS: 20-25 KTS SST: 29-30 CELSIUS OUTFLOW: STRONG RADIAL OTHER FACTORS: SLOT OF RELATIVELY DRY AIR WRAPPING INTO THE CORE ANALYSIS CONFIDENCE: INITIAL POSITION: HIGH 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: 09W IS FORECAST TO BEGIN TRACKING NORTHWESTWARD AS THE STR THAT IS CURRENTLY POSITIONED OVER SOUTHERN JAPAN MERGES WITH THE STR THAT IS SITUATED TO THE NORTHEAST OF 09W OVER THE NEXT 6-12 HOURS. A NORTHWESTWARD TRACK IS THEN EXPECTED TO PERSIST THROUGH TAU 96 AS 09W TRACKS ALONG THE SOUTHWESTERN PERIPHERY OF THE RESULTING STR. A PASSAGE OVER THE YAEYAMA ISLANDS IS FORECAST TO OCCUR JUST BEFORE TAU 60 AS THE SYSTEM CONTINUES TO HEAD TOWARD THE EASTERN COAST OF CHINA. A FINAL LANDFALL IS FORECAST TO TAKE PLACE SOON AFTER TAU 72 NEAR WENZHOU, CHINA. THROUGHOUT THE TRACK LEADING UP TO THE FINAL LANDFALL, THE WIND FIELD OF 09W IS EXPECTED TO REMAIN VERY LARGE WITH GALE-FORCE WINDS EXTENDING UP TO 300 NM FROM THE CENTER. 09W WILL THEN TRACK FURTHER INLAND INTO MAINLAND CHINA THROUGH TAU 96 BEFORE MAKING A NORTHWARD TURN AS THE SYSTEM ATTEMPTS TO ROUND THE WESTERN EXTENT OF THE STR. IN TERMS OF INTENSITY, 09W IS FORECAST TO CONTINUE SLIGHTLY WEAKENING THROUGH TAU 12 UNDER THE INFLUENCE OF THE MODERATE NORTHEASTERLY VERTICAL WIND SHEAR AND POTENTIAL EYEWALL REPLACEMENT CYCLE. FROM TAU 24 THROUGH TAU 48, THE INTENSITY IS EXPECTED TO MORE OR LESS BE MAINTAINED AS SHEAR DROPS TO BELOW 15 KTS. NEAR TAU 60, 09W IS EXPECTED TO ENTER AN AREA OF MUCH LOWER OCEAN HEAT CONTENT (BELOW 25 KJ), TRIGGERING ANOTHER BOUT OF WEAKENING AS THE SYSTEM APPROACHES THE COAST OF CHINA. AFTER LANDFALL, TERRAIN INTERACTION WILL CAUSE THE VORTEX TO RAPIDLY DETERIORATE WITH DISSIPATION FORECAST TO OCCUR AROUND TAU 120, WEST OF SHANGHAI. MODEL DISCUSSION: NUMERICAL MODEL TRACK GUIDANCE IS IN GOOD AGREEMENT THROUGH TAU 72 WITH NO SIGNIFICANT OUTLIERS AND A CROSS-TRACK SPREAD OF AROUND 100 NM. THE EC-AIFS AND EXPERIMENTAL GOOGLE DEEPMIND ARE NOTABLY ON THE EASTERN END OF THE GUIDANCE ENVELOPE, SUGGESTING A TRACK DIRECTLY OVER ISHIGAKIJIMA WHILE THE PHYSICS-BASED MODELS TRACK THE VORTEX CLOSER TO THE NORTHERN TIP OF TAIWAN. AFTER TAU 72, THE CROSS-TRACK SPREAD THEN OPENS UP TO ABOUT 280 NM AT TAU 120. THE JTWC TRACK FORECAST IS PLACED CLOSE TO THE MULTI-MODEL CONSENSUS THROUGH TAU 72 WITH HIGH CONFIDENCE AND THEN CLOSER TO THE GOOGLE DEEPMIND THROUGH TAU 120 WITH MEDIUM CONFIDENCE. INTENSITY GUIDANCE AGREES ON GRADUAL WEAKENING THROUGH TAU 60 FOLLOWED BY A MORE RAPID RATE OF WEAKENING AFTERWARD WITH NO SIGNIFICANT VARIATION BETWEEN THE RELIABLE INTENSITY GUIDANCE. THE JTWC INTENSITY FORECAST IS PLACED CLOSE TO THE CONSENSUS WITH OVERALL MEDIUM CONFIDENCE DUE TO INHERENT UNCERTAINTIES REVOLVING AROUND THE POTENTIAL EYEWALL REPLACEMENT CYCLE. FORECAST CONFIDENCE: TRACK 00-72 HR: HIGH TRACK 72-120 HR: MEDIUM INTENSITY 00-72 HR: MEDIUM INTENSITY 72-120 HR: MEDIUM// NNNN