WDPN31 PGTW 050300 MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI// SUBJ/PROGNOSTIC REASONING FOR SUPER TYPHOON 09W (BAVI) WARNING NR 017// RMKS/ 1. FOR METEOROLOGISTS. 2. 6 HOUR SUMMARY AND ANALYSIS. SUMMARY: INITIAL POSITION: 12.9N 148.9E INITIAL INTENSITY: 135 KTS GEOGRAPHIC REFERENCE: 253 NM EAST OF NAVSTA GUAM MOVEMENT PAST 6 HOURS: WEST-NORTHWESTWARD AT 07 KTS SIGNIFICANT WAVE HEIGHT: 45 FEET SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION: ANIMATED MULTISPECTRAL SATELLITE IMAGERY (MSI) DEPICTS SUPER TYPHOON (STY) 09W (BAVI) RESPONDING TO A BUILDING STR EXTENSION TO THE NORTHEAST AND SHIFTING ITS TRACK FROM WESTWARD TO WEST-NORTHWESTWARD. ANALYSIS OF THE VISIBLE SATELLITE IMAGERY REVEALS THE PRESENCE OF CIRRUS STRIATIONS INDICATING HIGHLY EFFICIENT UPPER-LEVEL OUTFLOW. CONCURRENTLY, THE FEEDER BANDS SPIRALING TOWARD THE EYEWALL ARE DISPLAYING TALLER, COLDER CLOUD TOPS (-79 C), BUT LOSING THEIR SYMMETRICAL, CONCENTRIC SPIRAL STRUCTURE, INDICATING SOME DRY AIR INTRUSION INTO THE OUTER CORE, PRIMARILY FROM THE SOUTH. WHILE CIMSS MPERC EYEWALL REPLACEMENT CYCLE (ERC) INDICATOR IS AT 68 PERCENT FOR THE FULL MODEL, RECENT MICROWAVE IMAGERY NO LONGER INDICATES AN ERC OCCURRING AT THIS TIME. ADDITIONAL SYNOPTIC AND MESOSCALE ENVIRONMENTAL DIAGNOSTICS REVEAL A CONTINUOUSLY FAVORABLE THERMODYNAMIC AND KINEMATIC REGIME, HIGHLIGHTED BY PREVIOUSLY MENTIONED VIGOROUS UPPER-LEVEL RADIAL OUTFLOW, MINIMAL DEEP-LAYER VERTICAL WIND SHEAR (VWS) RANGING BETWEEN 5-10 KTS AND ELEVATED SEA SURFACE TEMPERATURES (SST) OF 29-30 C. WITHIN THIS CONDUCIVE ENVIRONMENT, MSI SHOWS A NEARLY CLOUD-FREE EYE FEATURE MEASURING 20 NM IN DIAMETER WITH A SLIGHTLY WARMER THAN LAST WARNING CYCLE THERMAL SIGNATURE OF 18 C. THE INITIAL POSITION OF STY 09W IS THEREFORE ASSESSED WITH HIGH CONFIDENCE. CONCURRENTLY, THE INITIAL INTENSITY ESTIMATE IS ASSESSED AT 135 KTS WITH HIGH CONFIDENCE, SYNTHESIZED VIA A CONSENSUS OF AGENCY SUBJECTIVE DVORAK ASSESSMENTS AND OBJECTIVE SATELLITE-DERIVED INTENSITY AIDS. INITIAL WIND RADII BASIS: OBJECTIVE BEST TRACK CURRENT STEERING MECHANISM: BUILDING EASTERN EXTENSION OF A SUBTROPICAL RIDGE (STR) CENTERED TO THE NORTHWEST AGENCY DVORAK AND AUTOMATED FIXES: PGTW: T7.0 - 140 KTS RJTD: T7.0 - 140 KTS RCTP: T6.5 - 127 KTS KNES: T6.5 - 127 KTS CIMSS SATCON: 135 KTS AT 042230Z CIMSS ADT: 127 KTS AT 050100Z CIMSS AIDT: 125 KTS AT 050100Z CIMSS D-MINT: 137 KTS AT 042050Z CIMSS D-PRINT: 133 KTS AT 042350Z FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: FAVORABLE VWS: 5-10 KTS SST: 29-30 CELSIUS OUTFLOW: STRONG RADIAL OTHER FACTORS: MINOR IMPACTS FROM DRY AIR INTRUSION ANALYSIS CONFIDENCE: INITIAL POSITION: HIGH INITIAL INTENSITY: HIGH INITIAL WIND RADII: LOW 3. FORECAST REASONING. SIGNIFICANT FORECAST CHANGES: THERE ARE NO SIGNIFICANT CHANGES TO THE FORECAST FROM THE PREVIOUS WARNING. FORECAST DISCUSSION: EASTERN EXTENSION OF A STR ANCHORED TO THE NORTHEAST IS BEGINNING TO FIRMLY ESTABLISH ITSELF AS THE PRIMARY STEERING FORCE BEHIND THE WEST-NORTHWESTWARD TRACK OF STY 09W. AS THE RIDGING REBUILDS, KINEMATIC ACCELERATION WILL RESUME, DRIVING THE CYCLONE FURTHER ON A WEST-NORTHWESTWARD TRAJECTORY TOWARD THE MARIANA ISLANDS ARCHIPELAGO AND BEYOND THROUGH TAU 96. AFTERWARDS, STY 09W IS FORECAST TO EXECUTE A MORE POLEWARD TURN ALONG THE WEST-SOUTHWESTERN PERIPHERY OF THE DOMINANT STR. HOWEVER, EXTENDED-RANGE BIFURCATION EXISTS REGARDING WHETHER THE VORTEX WILL SHARPLY RECURVE AROUND THE RIDGE AXIS OR MAINTAIN A SHALLOWER TRAJECTORY CLOSER TO NORTHERN TAIWAN. REGARDING THERMODYNAMIC EVOLUTION, THE PEAK INTENSITY IS EXPECTED TO TEMPORARILY PLATEAU BEFORE ACHIEVING A SECONDARY MAXIMUM OF 140 KTS BETWEEN TAU 24 AND TAU 36, FACILITATED BY THE INTRODUCTION OF AN ADDITIONAL, ENHANCED EQUATORWARD AND WESTWARD DIVERGENT OUTFLOW CHANNEL. ANOTHER ERC IS STILL POSSIBLE AS INDICATED BY A RECENT, MESOSCALE HAFS RUN SHOWING POTENTIAL INITIATION OF THE PROCESS AROUND TAU 60. SIMULTANEOUSLY, AN INFLUX OF VWS WILL INITIATE A SLIGHT WEAKENING PHASE. DESPITE THIS PREDICTED DEGRADATION, THE SYSTEM WILL SUSTAIN ROBUST TYPHOON CHARACTERISTICS FEATURING A MASSIVELY EXPANDED WIND RADII ENVELOPE STRETCHING FROM THE NORTHERN PHILIPPINES TO THE SOUTHWEST THROUGH OKINAWA TO THE NORTHEAST. MODEL DISCUSSION: THE DETERMINISTIC NUMERICAL WEATHER PREDICTION TRACK GUIDANCE SUITE EXHIBITS ROBUST SPATIAL COHESION THROUGH TAU 72, HIGHLIGHTED BY A HIGHLY COMPACT CROSS-TRACK SPREAD OF A MERE 36 NM DURING THE CLOSEST POINT OF APPROACH (CPA) TO THE ISLANDS OF TINIAN AND ROTA. EXTENDED-RANGE SPATIAL GUIDANCE INTRODUCES INCREASED ENVELOPE DISPERSION AS WITNESSED BY A CROSS-TRACK SPREAD OF 220 AT THE FINAL TAU OF THE CURRENT FORECAST PERIOD. NAVGEM OPERATES AS THE LONE OUTLIER BY ACCELERATING A SHARP RECURVATURE SCENARIO TOWARD OKINAWA, WHEREAS THE REMAINDER OF THE DYNAMICAL CONSENSUS CLUSTERS ALONG A VECTOR DIRECTED AT NORTHERN TAIWAN. CONSEQUENTLY, THE JOINT TYPHOON WARNING CENTER (JTWC) LONG-TERM TRACK IS ISSUED WITH MEDIUM CONFIDENCE. WITH RESPECT TO INTENSITY PROFILES, HIGH-RESOLUTION MESOSCALE HAFS MODEL DEPICTS A RENEWED PHASE OF MODEST DEEPENING TO A PEAK OF 140-145 KTS, CATALYZED BY OPTIMIZED UPPER-LEVEL OUTFLOW MECHANISMS. CONVERSELY, THE BROADER DYNAMICAL CONSENSUS SUGGESTS A PROLONGED, GRADUAL DECAY INTERMINGLED WITH PERIODS OF INTENSITY MAINTENANCE. ALIGNING WITH THE HIGH-RESOLUTION MESOSCALE INDICATION AND THE CONTINUALLY CONDUCIVE MESOSCALE ENVIRONMENT, THE JTWC OFFICIAL INTENSITY FORECAST IS POSITIONED ALONG THE UPPER BOUNDARY OF THE MULTI-MODEL CONSENSUS, ACCOUNTING FOR THE PROBABILITY OF MINOR NEAR-TERM INTENSIFICATION OVER THE ENSUING 36 HOURS. AFTER TAU 96 ALL AVAILABLE GUIDANCE INDICATES A SHARPER WEAKENING TREND, AS WITNESSED BY A 15 KTS MAX WIND SPEEDS DECREASE BETWEEN TAU 96 AND TAU 120. FORECAST CONFIDENCE: TRACK 00-72 HR: HIGH TRACK 72-120 HR: MEDIUM INTENSITY 00-72 HR: MEDIUM INTENSITY 72-120 HR: MEDIUM// NNNN