WDPN31 PGTW 051500 MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI// SUBJ/PROGNOSTIC REASONING FOR SUPER TYPHOON 09W (BAVI) WARNING NR 019// RMKS/ 1. FOR METEOROLOGISTS. 2. 6 HOUR SUMMARY AND ANALYSIS. SUMMARY: INITIAL POSITION: 13.7N 146.9E INITIAL INTENSITY: 155 KTS GEOGRAPHIC REFERENCE: 117 NM EAST OF ANDERSEN AFB MOVEMENT PAST 6 HOURS: WEST-NORTHWESTWARD AT 12 KTS SIGNIFICANT WAVE HEIGHT: 52 FEET SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION: SUPER TYPHOON 09W HAS THE CLASSIC APPEARANCE OF AN EXTREMELY POWERFUL TROPICAL CYCLONE. OVER THE PAST THREE HOURS, THE SYSTEM HAS TAKEN A MENACING TURN WESTWARD TOWARD ROTA. ANIMATED ENHANCED INFRARED (EIR) SATELLITE IMAGERY DEPICTS A PERFECTLY CIRCULAR, 25 NM-WIDE EYE EMBEDDED IN A SYMMETRIC CENTRAL DENSE OVERCAST (CDO), SURROUNDED BY DENSE CONVECTIVE BANDING FEATURES. CLOUD TOP TEMPERATURES HAVE CONTINUED TO COOL TO -80 DEGREES CELSIUS, WITH A SOLID RING OF THE CMG SHADE ENCIRCLING THE EYE ON ANIMATED INFRARED IMAGERY ENHANCED VIA THE BD CURVE. CONCURRENTLY, THE EYE TEMPERATURE HAS WARMED TO 20 DEGREES CELSIUS. THIS ROBUST STRUCTURE IS SUPPORTED BY EXCEPTIONAL RADIAL OUTFLOW, ENABLING EFFICIENT VENTILATION IN ALL QUADRANTS AND SUSTAINING THE INTENSE CORE CONVECTION. A 050746Z WSF-M MWI PASS REVEALED AN INTENSE EYEWALL SURROUNDED BY MULTIPLE RAINBANDS, THOUGH THIS STRUCTURE DOES NOT YET SIGNIFY AN IMMINENT EYEWALL REPLACEMENT CYCLE (ERC), AS THESE BANDING FEATURES HAVE NOT FULLY CONSOLIDATED INTO A CLOSED CONCENTRIC RING. DATA FROM THE PGUA WSR-88D RADAR REVEALS HEAVY RAINBANDS SWEEPING OVER THE SOUTHERN MARIANA ISLANDS, WITH INBOUND WINDS GREATER THAN 150 KTS AT 16,000 FT AS THE EYEWALL COMES INTO SHARPER FOCUS. GROUND OBSERVATIONS FROM SAIPAN INTERNATIONAL AIRPORT INDICATE THAT TYPHOON-FORCE GUSTS OF 66 KTS HAVE ARRIVED. THE VORTEX IS NOW TRAVERSING VERY WARM SEA SURFACE TEMPERATURES (SST) OF 30-31 DEGREES CELSIUS AND VERY HIGH OCEAN HEAT CONTENT (OHC) OF 150 KJ PER SQUARE CM IN AN ENVIRONMENT OF LOW VERTICAL WIND SHEAR (VWS) AND RICH DEEP-LAYER MOISTURE. THESE FACTORS ARE EXCEPTIONALLY FAVORABLE FOR SUPPORTING A HIGH-END STORM. THE INITIAL POSITION IS ASSESSED WITH HIGH CONFIDENCE BASED ON THE SHARPLY DEFINED EYE ON EIR AND RADAR IMAGERY. THE INITIAL INTENSITY IS RAISED TO 155 KTS WITH MEDIUM CONFIDENCE BASED ON THE IMPROVED CONVECTIVE SIGNATURE AND THE UNANIMOUS SUBJECTIVE DVORAK FIXES OF T7.5 FROM PGTW, KNES, RJTD, AND RCTP, WHICH ARE WELL ABOVE THE OBJECTIVE ESTIMATES FROM CIMSS RANGING FROM 135 KTS TO 143 KTS. INITIAL WIND RADII BASIS: PERSISTENCE CURRENT STEERING MECHANISM: EASTERN EXTENSION OF A DEEP-LAYER SUBTROPICAL RIDGE (STR) CENTER 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: 143 KTS AT 051030Z CIMSS ADT: 140 KTS AT 0512000Z CIMSS AIDT: 139 KTS AT 051200Z CIMSS D-MINT: 135 KTS AT 050814Z CIMSS D-PRINT: 141 KTS AT 051200Z FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: HIGHLY FAVORABLE VWS: 10-15 KTS SST: 30-31 CELSIUS OUTFLOW: STRONG RADIAL ANALYSIS CONFIDENCE: INITIAL POSITION: HIGH INITIAL INTENSITY: MEDIUM INITIAL WIND RADII: MEDIUM 3. FORECAST REASONING. SIGNIFICANT FORECAST CHANGES: THE WESTWARD JOG NECESSITATED A SOUTHWARD SHIFT IN THE TRACK FORECAST AT TAU 12 AND TAU 24 BY 20 NM. FORECAST DISCUSSION: A RECENT SHIFT IN STORM MOTION DUE WEST HAS INCREASED THE POTENTIAL FOR A DIRECT LANDFALL ON OR VERY NEAR ROTA. CONSEQUENTLY, THE FORECAST TRACK AT TAU 12 AND TAU 24 HAS BEEN SHIFTED SOUTHWARD BY 20 NM, BRINGING THE CENTER DIRECTLY OVER THE ISLAND. WHILE THESE SHORT-TERM DEVIATIONS ARE DIFFICULT TO PREDICT, THE SYSTEM WILL RESUME A WEST-NORTHWESTWARD TRAJECTORY SHORTLY, STEERED BY A DEEP-LAYER STR ANCHORED TO THE NORTH. BY TAU 72, STY 09W WILL TURN NORTHWESTWARD AS IT ROUNDS THE SOUTHWESTERN PERIPHERY OF THE RIDGE. STY 09W IS AT OR VERY NEAR PEAK INTENSITY, AND IT WILL REMAIN A POWERFUL TROPICAL CYCLONE THROUGH THE FORECAST PERIOD. EXCEPTIONALLY FAVORABLE CONDITIONS PERSIST, CHARACTERIZED BY VERY HIGH OHC, LOW VWS, STRONG DIVERGENCE ALOFT, AND ABUNDANT MOISTURE. SLIGHT WEAKENING WILL BEGIN BY TAU 24 AS THE SYSTEM TRAVELS OVER LOWER OHC. THE WEAKENING WILL ACCELERATE AFTER TAU 36 DUE TO INCREASING VWS AND THE LIKELIHOOD OF STRUCTURAL DISRUPTIONS FROM ERC. BY TAU 72, AN UPPER-LEVEL RIDGE BUILDING SOUTH OF HONSHU WILL IMPART 20-25 KTS OF EASTERLY SHEAR ON THE SYSTEM. NORMALLY, THIS AMOUNT OF SHEAR WOULD RESULT IN MORE RAPID WEAKENING, BUT STY BAVI WILL UNDERGO MASSIVE EXPANSION IN SIZE, WITH GALE-FORCE WINDS EXTENDING NEARLY 300 NM OUTWARD FROM THE CENTER. THIS SUBSTANTIAL FOOTPRINT OF THE VORTEX WILL INSULATE THE CORE, MITIGATING THE DETRIMENTAL EFFECTS OF VWS. MODEL DISCUSSION: MODEL AGREEMENT IS GOOD THROUGH TAU 72, WITH A CROSS-TRACK SPREAD OF 95 NM. THE UNCERTAINTY ENVELOPE INCREASES TO 230 NM AND 320 NM AT TAU 96 AND TAU 120, RESPECTIVELY, WITH NAVGEM ON THE NORTHERNMOST BOUNDARY OF THE GUIDANCE ENVELOPE AND HWRF BEING THE SOUTHERNMOST OUTLIER. WITHIN THE CORE ENVELOPE, THE AI MODELS BIAS TOWARDS THE POLEWARD SIDE, WHEREAS THE TRADITIONAL PHYSICS-BASED MODELS SKEW EQUATORWARD. THE JTWC FORECAST TRACK IS INTENTIONALLY POSITIONED ALONG THE SOUTHERN EDGE OF THE GUIDANCE ENVELOPE AT TAU 12 AND TAU 24 TO ACCOUNT FOR THE UNEXPECTED, INITIAL WESTWARD MOTION. AFTER THE FIRST 24 HOURS, THE FORECAST TRACK IS LAID ON THE MULTI-MODEL CONSENSUS WITH MEDIUM CONFIDENCE, ALIGNING CLOSELY WITH THE CENTER OF THE TIGHTLY CLUSTERED PHYSICS-BASED MODELS. COAMPS-TC, HAFS-A, AND THE EXPERIMENTAL GOOGLE DEEPMIND MODEL PREDICT A NEAR-STEADY INTENSITY TREND THROUGH TAU 36, FOLLOWED BY A FASTER RATE OF WEAKENING. THE JTWC INTENSITY FORECAST IS SET HIGHER THAN ALL THE INTENSITY AIDS AT TAU 12 AND THEN CLOSELY MIRRORS THE HAFS-A AND DEEPMIND SOLUTIONS FROM TAU 24 TO TAU 120 WITH MEDIUM CONFIDENCE. FORECAST CONFIDENCE: TRACK 00-72 HR: MEDIUM TRACK 72-120 HR: MEDIUM INTENSITY 00-72 HR: MEDIUM INTENSITY 72-120 HR: MEDIUM// NNNN