WDPN31 PGTW 052100 MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI// SUBJ/PROGNOSTIC REASONING FOR SUPER TYPHOON 09W (BAVI) WARNING NR 020// RMKS/ 1. FOR METEOROLOGISTS. 2. 6 HOUR SUMMARY AND ANALYSIS. SUMMARY: INITIAL POSITION: 14.0N 146.1E INITIAL INTENSITY: 155 KTS GEOGRAPHIC REFERENCE: 53 NM EAST OF ROTA MOVEMENT PAST 6 HOURS: WEST-NORTHWESTWARD AT 08 KTS SIGNIFICANT WAVE HEIGHT: 54 FEET SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION: ANIMATED ENHANCED INFRARED (EIR) SATELLITE IMAGERY DEPICTS A VERY SYMMETRICAL, 25 NM IN DIAMETER, EYE FEATURE SURROUNDED BY A UNIFORM CENTRAL DENSE OVERCAST OF SUPER TYPHOON (STY) 09W (BAVI). EVALUATION OF CURRENT SYNOPTIC AND MESOSCALE DIAGNOSTICS REVEALS A CONTINUOUSLY FAVORABLE KINEMATIC AND THERMODYNAMIC ENVIRONMENT, UNDERSCORED BY MINIMAL DEEP-LAYER VERTICAL WIND SHEAR (VWS) OF 5-10 KTS, ELEVATED SEA SURFACE TEMPERATURES (SST) OF 29-30 C WITH HIGH OCEAN HEAT CONTENT, AND VIGOROUS UPPER-LEVEL RADIAL OUTFLOW. STY BAVI IS EXECUTING A TRAJECTORY SHIFT FROM BRIEFLY WESTWARD TO WEST-NORTHWESTWARD IN RESPONSE TO A CONSOLIDATING SUBTROPICAL RIDGE (STR) EXTENSION TO THE NORTHEAST. DEEP CONVECTIVE FEEDER BANDS SPIRALING TOWARD THE CENTRAL CORE EXHIBIT EXTREMELY COLD CLOUD TOPS REACHING -82 C, WITH THE EYE TEMPERATURE OF 19 C, RESULTING IN AN EXTREME THERMAL DIFFERENTIAL OF 101 C. BASED ON THE EXCELLENT EYE PRESENTATION, THE INITIAL SYNOPTIC POSITION IS ANCHORED WITH HIGH CONFIDENCE. AN INITIAL INTENSITY OF 155 KTS IS ESTABLISHED WITH MEDIUM CONFIDENCE, DERIVED FROM A STRICT CONSENSUS OF AGENCY SUBJECTIVE DVORAK ASSESSMENTS, WHILE CIMSS OBJECTIVE SATELLITE-DERIVED INTENSITY ESTIMATES ARE STILL HOVERING AROUND 140-145 KTS, WITH THE CURRENT INTENSITY (CI) READING FROM ADT OF T7.1. INITIAL WIND RADII BASIS: OBJECTIVE BEST TRACK CURRENT STEERING MECHANISM: EASTERN EXTENSION OF A DEEP-LAYER SUBTROPICAL RIDGE (STR) CENTERED NEAR OKINAWA AGENCY DVORAK AND AUTOMATED FIXES: PGTW: T7.5 - 155 KTS RJTD: T7.5 - 155 KTS RCTP: T7.5 - 155 KTS KNES: T7.5 - 155 KTS CIMSS SATCON: 141 KTS AT 051800Z CIMSS ADT: 143 KTS AT 051800Z CIMSS AIDT: 140 KTS AT 051800Z CIMSS D-MINT: 147 KTS AT 051611Z CIMSS D-PRINT: 151 KTS AT 051800Z FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: HIGHLY FAVORABLE VWS: 5-10 KTS SST: 29-30 CELSIUS OUTFLOW: STRONG RADIAL 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: SYNOPTIC STEERING DYNAMICS ARE CURRENTLY DOMINATED BY THE STILL DEVELOPING EASTERN EXTENSION OF A NORTHWESTERN STR, WHICH WILL FUNCTION AS THE PRIMARY DRIVER FOR THE WEST-NORTHWESTWARD PROPAGATION OF STY 09W. AS THIS RIDGING MECHANISM REBUILDS, KINEMATIC ACCELERATION WILL INITIATE, PROPELLING THE CYCLONE THROUGH THE MARIANA ISLANDS ARCHIPELAGO ON A WEST-NORTHWESTWARD HEADING THROUGH TAU 96. BEYOND THIS TEMPORAL THRESHOLD, STY 09W IS FORECAST TO ALTER ITS VECTOR MORE POLEWARD ALONG THE WEST-SOUTHWESTERN PERIPHERY OF THE STEERING STR. EXTENDED-RANGE TRAJECTORY BIFURCATION INTRODUCES UNCERTAINTY REGARDING WHETHER THE METEOROLOGICAL SYSTEM WILL EXECUTE A SHARP RECURVATURE AROUND THE RIDGE AXIS OR SUSTAIN A SHALLOWER APPROACH TOWARD NORTHERN TAIWAN, WITH THE LATTER BEING CURRENTLY HEAVILY FAVORED AMONG THE PREDICTION MODELS. THERMODYNAMICALLY, THE CYCLONE IS PROJECTED TO UNDERGO A BRIEF PHASE OF MODEST DEGRADATION DRIVEN BY A TEMPORARY REDUCTION IN UPPER-LEVEL OUTFLOW POTENTIAL. RESUMPTION OF DEEPENING IS ANTICIPATED POST TAU 12, WITH INTENSIFICATION PROPAGATING THROUGH TAU 36 AS A HIGHLY EFFICIENT, AUXILIARY WESTWARD DIVERGENT OUTFLOW CHANNEL EXCAVATES. SUBSEQUENT TO THIS SECONDARY PEAK, AN ESCALATION IN DEEP-LAYER VWS COUPLED WITH CONCURRENT OUTFLOW REDUCTION WILL ARREST INTENSIFICATION AND LEAD TO A GRADUAL, BUT STEADY WEAKENING. NEVERTHELESS, THE SYSTEM WILL PRESERVE FORMIDABLE TYPHOON CHARACTERISTICS, MANIFESTING A MASSIVELY EXPANDED WIND RADII ENVELOPE. MODEL DISCUSSION: DETERMINISTIC NUMERICAL WEATHER PREDICTION TRACK GUIDANCE REMAINS HIGHLY COHESIVE THROUGH TAU 96, EVIDENCED BY AN EXCEPTIONALLY COMPACT CROSS-TRACK SPREAD OF ONLY 8 NM DURING THE CLOSEST POINT OF APPROACH (CPA) TO ROTA AND 65 NM AT TAU 72. HOWEVER, SPATIAL DISPERSION EXPANDS IN THE EXTENDED RANGE, CULMINATING IN A 270 NM CROSS-TRACK SPREAD BY THE FINAL FORECAST TAU. WITHIN THIS LATE-STAGE BIFURCATION, NAVGEM FUNCTIONS AS THE SOLE OUTLIER BY ACCELERATING A RECURVATURE PATH CLOSER TO OKINAWA, WHILE THE BULK OF THE DYNAMICAL CONSENSUS CLUSTERS ALONG A VECTOR ORIENTED TOWARD NORTH OF TAIWAN. THE ALONG-TRACK SPREAD ENVELOPE IS ESTIMATED AT 120 NM AT TAU 72. IN LIGHT OF THIS OVERALL DIVERGENCE, THE JTWC EXTENDED TRACK TRAJECTORY IS ISSUED WITH MEDIUM CONFIDENCE. REGARDING INTENSITY PROFILES, THE HIGH-RESOLUTION MESOSCALE HAFS MODEL INDICATES ANOTHER PHASE OF MODEST INTENSIFICATION PEAKING AT 145-150 KTS, DRIVEN BY OPTIMIZED UPPER-LEVEL OUTFLOW MECHANISMS. CONVERSELY, THE BROADER DYNAMICAL CONSENSUS ADVOCATES FOR A PROLONGED, GRADUAL DECAY PRECEDED BY AN INITIAL PHASE OF INTENSITY MAINTENANCE. IN ALIGNMENT WITH THE FAVORABLE MESOSCALE ENVIRONMENT AND HAFS GUIDANCE, THE JTWC OFFICIAL INTENSITY PROGNOSIS LIES ON THE UPPER BOUNDARY OF THE MULTI-MODEL CONSENSUS, REFLECTING THE PROBABILITY OF MINOR NEAR-TERM DEEPENING OVER THE NEXT 36 HOURS FOLLOWING A BRIEF WEAKENING. BEYOND TAU 36, NEARLY ALL MEMBERS OF THE AVAILABLE NUMERICAL CONSENSUS AGREE ON A STEADY WEAKENING TREND. FORECAST CONFIDENCE: TRACK 00-72 HR: HIGH TRACK 72-120 HR: MEDIUM INTENSITY 00-72 HR: MEDIUM INTENSITY 72-120 HR: MEDIUM// NNNN