WDPN31 PGTW 091500 MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI// SUBJ/PROGNOSTIC REASONING FOR TYPHOON 09W (BAVI) WARNING NR 035// RMKS/ 1. FOR METEOROLOGISTS. 2. 6 HOUR SUMMARY AND ANALYSIS. SUMMARY: INITIAL POSITION: 19.2N 128.8E INITIAL INTENSITY: 100 KTS GEOGRAPHIC REFERENCE: 441 NM SOUTH OF KADENA AB MOVEMENT PAST 6 HOURS: NORTH-NORTHWESTWARD AT 05 KTS SIGNIFICANT WAVE HEIGHT: 50 FEET SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION: ANIMATED ENHANCED INFRARED (EIR) SATELLITE IMAGERY DEPICTS TYPHOON (TY) 09W (BAVI) WITH AN INCREASINGLY ASYMMETRICAL CONVECTIVE STRUCTURE, AS THE SYSTEM IS CONFRONTED BY HOSTILE DEEP-LAYER NORTHEASTERLY VERTICAL WIND SHEAR (VWS) OF 25 KTS, WHICH HAS TILTED AND DISRUPTED THE VERTICAL AXIS OF THE STORM. ADDITIONALLY, THE VORTEX HAS EXPERIENCED STRUCTURAL VERTICAL DECOUPLING AND STEERING LAYER COMPRESSION. THIS HAS SEVERED TYPHOON 09W (BAVI) FROM THE RAPID, DEEP-LAYER STEERING FLOW, LEAVING THE LLCC GOVERNED BY SHALLOWER, SIGNIFICANTLY SLOWER LOWER-TROPOSPHERIC STEERING MECHANISM, MANIFESTED BY A DECELERATION IN TRANSLATIONAL VELOCITY FROM 10 KTS TO 5 KTS. THIS REDUCED TRANSLATION SPEED IS CONDUCIVE TO LOCALIZED SELF-INDUCED UPWELLING, DRIVING SEA SURFACE COOLING ALONG THE TRACK AND LIMITING ANY NEAR-TERM THERMODYNAMIC INTENSITY RECOVERY. FURTHERMORE, THE HOSTILE 25 KTS VWS REGIME HAS LIKELY ARRESTED THE COMPLETION OF THE ONGOING ERC BY INDUCING SEVERE CONVECTIVE ASYMMETRY AND PREVENTING THE OUTER WRAPPING EYEWALL FROM CONSOLIDATING OR CLOSING SYMMETRICALLY, AS REVEALED BY A 090900Z F17 SSMIS 91 GHZ MICROWAVE PASS SHOWING A NEARLY FULLY ERODED INNER EYEWALL AND AN INCOMPLETE WRAPPING OF THE SECONDARY EYEWALL. WHILE VIGOROUS UPPER-LEVEL EQUATORWARD AND WESTWARD OUTFLOW AND ELEVATED SEA SURFACE TEMPERATURES (SST) OF 29-30 C ARE PRESENT, THE SYSTEM IS UNABLE TO EXPLOIT THIS DUE TO STRUCTURAL CORRUPTION. BASED ON THE OBSCURED, CLOUD-FILLED LOW-LEVEL CIRCULATION CENTER (LLCC) AND THE LOW-LEVEL CLOUD TRACING OVER THE NORTHERN SEMICIRCLE, THE INITIAL SYNOPTIC POSITION IS LAID WITH MEDIUM CONFIDENCE, WITH THE INITIAL INTENSITY ASSESSED AT 100 KTS WITH MEDIUM CONFIDENCE TO ALIGN WITH THE DEGRADED CORE STRUCTURE AND SUBJECTIVE DVORAK TRENDS AND OBJECTIVE INTENSITY ESTIMATES LISTED BELOW. INITIAL WIND RADII BASIS: OBJECTIVE BEST TRACK CURRENT STEERING MECHANISM: ELONGATED SUBTROPICAL RIDGING CENTERED TO THE NORTHEAST AGENCY DVORAK AND AUTOMATED FIXES: PGTW: T5.0 - 90 KTS RJTD: T5.5 - 102 KTS RCTP: T4.5 - 77 KTS KNES: T5.0 - 90 KTS CIMSS SATCON: 92 KTS AT 091200Z CIMSS ADT: 87 KTS AT 091200Z CIMSS AIDT: 85 KTS AT 091200Z CIMSS D-MINT: 99 KTS AT 090859Z CIMSS D-PRINT: 86 KTS AT 091200Z FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: MARGINALLY FAVORABLE VWS: 20-25 KTS SST: 29-30 CELSIUS OUTFLOW: STRONG EQUATORWARD ANALYSIS CONFIDENCE: INITIAL POSITION: MEDIUM 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: OVERALL STEERING DYNAMICS FOR TY 09W REMAIN GOVERNED BY AN ELONGATING AND CONSOLIDATING NORTHEASTERN STR, WHICH WILL SUSTAIN A GENERALLY NORTHWESTWARD TRANSLATIONAL VECTOR THROUGH LANDFALL. ALONG THIS TRAJECTORY, TY 09W IS FORECAST TO TRANSIT THE IMMEDIATE PROXIMITY OF ISHIGAKIJIMA JUST PRIOR TO TAU 36. SUBSEQUENT TO THIS MARITIME PASSAGE AND SOON AFTER TAU 48, THE SYSTEM WILL EXECUTE LANDFALL OVER THE EASTERN CHINESE SEABOARD. NOTWITHSTANDING CENTRAL CORE KINEMATICS, AN EXPANSIVE GALE-FORCE WIND RADII FIELD WILL ENCOMPASS A MASSIVE GEOGRAPHIC FOOTPRINT STRETCHING FROM TAIWAN THROUGH THE RYUKYU ARC TO OKINAWA. THERMODYNAMICALLY, INTENSITY FLUCTUATIONS ARE HIGHLY PROBABLE OVER THE INITIAL 36 HOURS DUE TO INHERENT PREDICTIVE UNCERTAINTIES GOVERNING THE ONGOING ERC AND FLUCTUATIONS IN VWS. A TRANSIENT RELAXATION IN VWS NEAR TAU 12 PRESENTS A WINDOW WERE DEGRADATION INCURRED DURING THE ERC MAY STABILIZE, ALLOWING FOR MINOR INTENSIFICATION OR SUSTAINMENT OF MAXIMUM SUSTAINED SPEEDS FOR AN ENSUING 12-HOUR PERIOD. ADVANCING BEYOND TAU 24, HOWEVER, A RENEWED ESCALATION IN VWS COUPLED WITH CYCLONE DISPLACEMENT AWAY FROM THE HIGHLY EFFICIENT EQUATORWARD OUTFLOW CHANNEL WILL ARREST DEVELOPMENT. CONCURRENTLY, TY BAVI WILL TRANSIT OUT OF ROBUST OCEAN HEAT CONTENT REGIME ALONG ITS PATH, BEGINNING A TERMINAL DECAY PHASE NEAR TAU 36. TERRESTRIAL FRICTION INDUCED BY THE POST-TAU 48 LANDFALL WILL CATALYZE A RAPID WEAKENING TREND. ONCE SITUATED INLAND OVER THE ASIAN CONTINENT, LAND INTERACTION AND ENGAGEMENT WITH DEEP-LAYER BAROCLINICITY WILL FORCE THE REMNANT VORTEX TO DEFLECT NORTHWARD AND SUBSEQUENTLY NORTHEASTWARD, WHILE ULTIMATELY COMPLETING DISSIPATION. MODEL DISCUSSION: DETERMINISTIC NUMERICAL WEATHER PREDICTION TRACK GUIDANCE EXHIBITS ROBUST COHESION THROUGH THE PRE-LANDFALL PHASE, HIGHLIGHTED BY A TIGHT CROSS-TRACK ENVELOPE SPREAD OF A MERE 45 NM WHEN OMITTING THE LONE OUTLIER, NAVGEM. WHILE THE VAST MAJORITY OF PHYSICS-BASED DYNAMICAL SUITES DEPICT THE AFOREMENTIONED NORTHWARD AND NORTHEASTWARD DEFLECTION POST-LANDFALL, NAVGEM CONTINUES TO MAINTAIN A PERSISTENT WESTWARD TRAJECTORY. OF SIGNIFICANT DIAGNOSTIC INTEREST, THE EXPERIMENTAL AI ENSEMBLE ADVOCATES FOR A SLIGHTLY MORE EASTERN TRACK, BRINGING THE LLCC EAST OF ISHIGAKIJIMA AND PROJECTING AN ONSHORE LANDING ADDITIONAL 25 NM NORTHEAST OF THE PHYSICS-BASED CONSENSUS MEAN. WEIGHING THESE DIVERGENT SPATIAL SOLUTIONS, THE OFFICIAL JTWC TRACK PROGNOSIS IS POSITIONED MARGINALLY TO THE EAST OF THE MULTI-MODEL CONSENSUS MEAN TO COUNTERBALANCE THE NAVGEM WESTWARD BIAS. REGARDING INTENSITY PROFILES, NUMERICAL GUIDANCE UNANIMOUSLY AGREES UPON AN INITIALLY SLUGGISH DECAY OR STEADY-STATE MAINTENANCE THROUGH THE FIRST 36 TO 48 HOURS, SUCCEEDED BY RAPID OVERLAND DISINTEGRATION. DETERMINISTIC GFS IS CURRENTLY THE ONLY MODEL INDICATING POTENTIAL FOR SLIGHT INTENSIFICATION (UP BY 5-10 KTS) BEFORE TAU 36. PREVIOUSLY MOST AGGRESSIVE HAFS NOW INDICATES A MORE RAPID DECAY OVER THE NEXT 24 HOURS, FOLLOWED BY A STABILIZATION OVER THE FOLLOWING 12 HOURS, ENDING WITH RAPID TERMINAL DECAY AFTERWARD. CONSEQUENTLY, THE JTWC OFFICIAL INTENSITY FORECAST IS ISSUED WITH MEDIUM CONFIDENCE AND IS PLACE NEAR THE MULTI-MODEL CONSENSUS. FORECAST CONFIDENCE: TRACK 00-72 HR: HIGH TRACK 72-120 HR: MEDIUM INTENSITY 00-72 HR: MEDIUM INTENSITY 72-120 HR: MEDIUM// NNNN