WDPN31 PGTW 050900 MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI// SUBJ/PROGNOSTIC REASONING FOR SUPER TYPHOON 09W (BAVI) WARNING NR 018// RMKS/ 1. FOR METEOROLOGISTS. 2. 6 HOUR SUMMARY AND ANALYSIS. SUMMARY: INITIAL POSITION: 13.4N 148.1E INITIAL INTENSITY: 145 KTS GEOGRAPHIC REFERENCE: 188 NM EAST OF ANDERSEN AFB MOVEMENT PAST 6 HOURS: NORTHWESTWARD AT 09 KTS SIGNIFICANT WAVE HEIGHT: 48 FEET SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION: ANIMATED MULTISPECTRAL SATELLITE IMAGERY (MSI) DEPICTS AN EXTREMELY POWERFUL SUPER TYPHOON (STY) STEADILY APPROACHING THE MARIANA ISLANDS. AFTER A BRIEF JOG TO THE NORTH, STY BAVI HAS RESUMED ITS WEST-NORTHWEST MOTION AT A HIGHER RATE OF 9 KTS. THE 3-HOURLY JT UPDATED POSITION PRODUCT (JTUP) WILL BE PRODUCED BEGINNING AT 040900Z. THE COLD CLOUD TOPS ASSOCIATED WITH THE CENTRAL DENSE OVERCAST HAVE SIGNIFICANTLY COOLED, WITH A THICK RING OF THE CMG SHADE IN THE BD CURVE-ENHANCED INFRARED IMAGE NEARLY ENCIRCLING THE EYE. POSSESSING A DIAMETER OF 25 NM, THE EYE HAS CLEARED OUT, AND GALE-FORCE WINDS NOW EXTEND 170 NM OUTWARD FROM THE CENTER. THE PERFECTLY CIRCULAR EYE IS VISIBLE ON THE PGUA WSR-88D RADAR, AND RAIN BANDS ARE SWEEPING OVER THE SOUTHERN MARIANA ISLANDS FROM NORTH TO SOUTH. OBSERVATIONS FROM SAIPAN AND GUAM INDICATE THAT GUSTS HAVE INCREASED TO NEAR 40 KTS. RECENT MICROWAVE RADIOMETER PASSES FROM AMSR2 AT 050336Z AND SSMIS AT 050553Z PROVIDED EVIDENCE THAT AN EYEWALL REPLACEMENT CYCLE (ERC) IS CURRENTLY NOT UNDERWAY BY SHOWING IN THE 37 GHZ IMAGE MULTIPLE INCOMPLETE RINGS SPIRALING INTO THE CENTER. HOWEVER, SUCH A CONVECTIVE STRUCTURE IS QUITE SUSCEPTIBLE TO ADDITIONAL ERC EVENTS, AND THE FULL MODEL FROM THE CIMSS MPERC ALGORITHM ESTIMATES A 62 PERCENT CHANCE OF ERC ONSET. THE ENVIRONMENT IS HIGHLY CONDUCIVE FOR INTENSIFICATION, CHARACTERIZED BY HIGH OCEAN HEAT CONTENT (OHC) OF 125 KJ PER SQUARE CM, LOW VERTICAL WIND SHEAR (VWS), ABUNDANT DEEP-LAYER MOISTURE, AND EXCELLENT RADIAL OUTFLOW. THE INITIAL POSITION IS ASSESSED WITH HIGH CONFIDENCE BASED ON THE SHARPLY DEFINED EYE ON VISIBLE HIMAWARI-9 IMAGERY. THE INITIAL INTENSITY IS RAISED TO 145 KTS WITH HIGH CONFIDENCE BASED ON THE SUBSTANTIAL IMPROVEMENTS DISCUSSED ABOVE AND A BLEND OF T7.0-7.5 SUBJECTIVE DVORAK FIXES FROM JTWC, KNES, RJTD, AND RCTP. INITIAL WIND RADII BASIS: SCATTEROMETER DATA CURRENT STEERING MECHANISM: EASTERN EXTENSION OF A DEEP-LAYER SUBTROPICAL RIDGE (STR) CENTER NEAR OKINAWA AGENCY DVORAK AND AUTOMATED FIXES: PGTW: T7.0 - 140 KTS RJTD: T7.5 - 155 KTS RCTP: T7.0 - 140 KTS KNES: T7.0 - 140 KTS CIMSS SATCON: 140 KTS AT 050600Z CIMSS ADT: 137 KTS AT 050600Z CIMSS AIDT: 137 KTS AT 050600Z CIMSS D-MINT: 140 KTS AT 050553Z CIMSS D-PRINT: 131 KTS AT 050600Z FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: HIGHLY FAVORABLE VWS: 10-15 KTS SST: 29-30 CELSIUS OUTFLOW: STRONG RADIAL ANALYSIS CONFIDENCE: INITIAL POSITION: HIGH INITIAL INTENSITY: MEDIUM INITIAL WIND RADII: MEDIUM 3. FORECAST REASONING. SIGNIFICANT FORECAST CHANGES: THE FORECAST TRACK AT THE TIME OF PASSAGE THROUGH THE MARIANA ISLANDS HAS SHIFTED 15 NM POLEWARD, AND THE NEAR-TERM INTENSITY FORECAST HAS BEEN INCREASED BY 10 KTS. FORECAST DISCUSSION: STY 09W HAS BEGUN A FASTER RATE OF MOTION TOWARDS THE WEST-NORTHWEST, WHICH WILL CONTINUE TO TAU 36 AS IT APPROACHES A STRONG STR CENTERED OVER THE RYUKYU ISLANDS. THE RIDGE WILL FLATTEN THE TRACK TO BE MORE WESTERLY FROM TAU 36 TO TAU 72. AT THE END OF THE FORECAST PERIOD, THE SYSTEM WILL BEGIN TO ROUND THE SOUTHWEST PERIPHERY OF THE STR AND TURN TOWARDS THE NORTHWEST. THE ENVIRONMENT IS BECOMING EVEN MORE CONDUCIVE FOR INTENSIFICATION. AN UPPER-LEVEL TROUGH UPSTREAM OF THE TYPHOON IS ACTIVELY DRAWING MASS FROM THE TYPHOON AND ENHANCING WESTWARD AND POLEWARD OUTFLOW. FURTHERMORE, STY 09W WILL MOVE OVER A POOL OF HIGHER OHC IN EXCESS OF 150 KJ PER SQUARE CM AND WARMER SEA SURFACE TEMPERATURE (SST) OF 30-31 DEGREES CELSIUS, WHILE THE UPPER-LEVEL DIVERGENCE INCREASES AS A RESULT OF THE TROUGH. THESE FACTORS WILL FUEL ADDITIONAL NEAR-TERM INTENSIFICATION AS THE LARGE CIRCULATION APPROACHES AND PASSES THE SOUTHERN MARIANA ISLANDS. THE ONLY INHIBITING FACTOR IS ERC POTENTIAL, THE TIMING, DURATION, AND IMPACT OF WHICH CANNOT BE RELIABLY PREDICTED WITH HIGH FIDELITY. SLOW WEAKENING WILL COMMENCE AT TAU 48 DUE TO INCREASING VWS AND POSSIBLE ERC EXPLICITLY DEPICTED BY HAFS-A. AT TAUS 96 AND 120, THE SYSTEM WILL WEAKEN MORE QUICKLY WHEN IT TRAVERSES OVER LOWER OHC IN THE FACE OF MODERATE TO HIGH VWS. THE CIRCULATION OF 09W IS EXPANDING, AND GALE-FORCE WINDS WILL EXTEND OUTWARD TO NEARLY 300 NM FROM THE CENTER AT TAU 120. IMPACTS WILL EXTEND FAR FROM THE CENTER. MODEL DISCUSSION: DUE TO A NORTHWARD JOG WITHIN THE PAST SIX HOURS, THE GUIDANCE ENVELOPE HAS SHIFTED NORTHWARD, NECESSITATING A SLIGHT POLEWARD ADJUSTMENT OF THE JTWC FORECAST TRACK FROM TAU 12 TO TAU 36. THE MODEL TRACKERS REMAIN TIGHTLY CLUSTERED TO TAU 72 WITH A CROSS-TRACK SPREAD OF 110 NM. THE SPREAD INCREASES TO 225 NM AT TAU 120 WITH NAVGEM AND THE AI MODELS ON THE POLEWARD SIDE AND GALWEM AND HWRF ON THE EQUATORWARD SIDE. NEARLY ALL OF THE GUIDANCE TAKES THE STORM CENTER BETWEEN TINIAN AND ROTA. THE JTWC TRACK IS LAID WITH HIGH CONFIDENCE NEAR THE MULTI-MODEL CONSENSUS, WHICH IS CLOSEST TO JGSM, GFS, AND ECMWF. STY BAVI CONTINUES TO PERFORM EXCEPTIONALLY WELL, INTENSIFYING TO LEVELS ABOVE THE SOLUTIONS FROM NEARLY ALL OF THE RELIABLE INTENSITY AIDS. HAFS-A REMAINS THE MOST AGGRESSIVE MEMBER AND DEPICTS A PEAK OF 155-160 KTS. GIVEN RECENT TRENDS AND THE OPTIMAL ENVIRONMENT, A HIGHER PEAK THAN FORECAST IS WELL WITHIN THE REALM OF POSSIBILITY. HAFS-A, COAMPS-TC, AND THE EXPERIMENTAL GOOGLE DEEPMIND MODEL DEPICT A GRADUAL WEAKENING TREND BY TAU 24-48 AND A STEADIER RATE BY 72-96. THE JTWC INTENSITY FORECAST IS AT THE UPPER END OF THE RELIABLE GUIDANCE AND FOLLOWS THE AVERAGE RATE OF DECLINE DEPICTED BY THESE MODELS. FORECAST CONFIDENCE: TRACK 00-72 HR: HIGH TRACK 72-120 HR: HIGH INTENSITY 00-72 HR: MEDIUM INTENSITY 72-120 HR: MEDIUM// NNNN