WDPN31 PGTW 061500 MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI// SUBJ/PROGNOSTIC REASONING FOR SUPER TYPHOON 09W (BAVI) WARNING NR 023// RMKS/ 1. FOR METEOROLOGISTS. 2. 6 HOUR SUMMARY AND ANALYSIS. SUMMARY: INITIAL POSITION: 15.4N 142.7E INITIAL INTENSITY: 140 KTS GEOGRAPHIC REFERENCE: 163 NM NORTHWEST OF ANDERSEN AFB MOVEMENT PAST 6 HOURS: WEST-NORTHWESTWARD AT 14 KTS SIGNIFICANT WAVE HEIGHT: 54 FEET SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION: ANIMATED ENHANCED INFRARED (EIR) SATELLITE IMAGERY DEPICTS A 20 NM-WIDE EYE EMBEDDED WITHIN A MORE RAGGED CENTRAL DENSE OVERCAST (CDO). ON INFRARED IMAGERY ENHANCED VIA THE BD CURVE, THE SPATIAL EXTENT OF THE WHITE SHADE HAS SIGNIFICANTLY DIMINISHED OVER THE PAST SEVERAL HOURS, WHICH CORRELATES WITH THE DECREASING DVORAK FINAL T-NUMBERS. HOWEVER, DEEP CONVECTION WITH VERY COLD TOPS MEASURING -81 DEGREES CELSIUS HAS FLARED UP OVER THE EASTERN SEMICIRCLE OF THE CDO AND IS ACTIVELY WRAPPING AROUND THE EYEWALL. WHILE THE UPPER-LEVEL OUTFLOW REMAINS RESTRICTED ON THE EASTWARD FLANK DUE TO LOW TO MODERATE EASTERLY VERTICAL WIND SHEAR (VWS), THE VENTILATION IS ROBUST ON THE WESTERN SIDE, ENHANCED BY AN UPPER-LEVEL TROUGH PASSING OVER THE PHILIPPINES. RECENT PASSES BY LOW-EARTH ORBITING SATELLITES PROVIDED CRITICAL DATA ON THE STORM'S STRUCTURAL EVOLUTION. A 060800Z SSMIS PASS DEPICTS A ROBUST INNER EYEWALL NEARLY ENCIRCLED BY AN OUTER RING OF DEEP CONVECTION. THIS PARTIAL EYEWALL REPLACEMENT CYCLE (ERC) IS LIKELY RESPONSIBLE FOR THE RECENT DEGRADATION OF THE CDO AND THE OVERALL WEAKENING OF THE SYSTEM. ADDITIONALLY, DATA FROM A 060832Z RCM-2 SAR PASS AND A 061131Z ASCAT-B PASS INDICATE THAT THE EXTENT OF STORM-FORCE WINDS HAS SIGNIFICANTLY EXPANDED, REFLECTING THE MASSIVE SIZE OF THE WIND FIELD. THE ENVIRONMENT IS STILL FAVORABLE FOR THE MAINTENANCE OF SUPER TYPHOON (STY) BAVI. THE OCEAN FEATURES VERY WARM SEA SURFACE TEMPERATURES (SST) AND HIGH OCEAN HEAT CONTENT (OHC), WHILE THE TROPOSPHERE SUPPORTS MODERATE DIVERGENCE ALOFT AND ABUNDANT DEEP-LAYER MOISTURE. THE INITIAL POSITION IS ASSESSED WITH HIGH CONFIDENCE BASED ON THE SHARPLY DEFINED EYE ON EIR IMAGERY. THE INITIAL INTENSITY HAS BEEN LOWERED TO 140 KTS WITH MEDIUM CONFIDENCE BASED ON THE SUBJECTIVE DVORAK FIXES OF T7.0 FROM JTWC, KNES, AND RJTD. INITIAL WIND RADII BASIS: SCATTEROMETER AND SAR DATA CURRENT STEERING MECHANISM: EASTERN EXTENSION OF A DEEP-LAYER SUBTROPICAL RIDGE (STR) CENTERED NEAR OKINAWA AGENCY DVORAK AND AUTOMATED FIXES: PGTW: T7.0 - 140 KTS RJTD: T7.0 - 140 KTS RCTP: T7.5 - 155 KTS KNES: T7.0 - 140 KTS CIMSS SATCON: 142 KTS AT 060900Z CIMSS ADT: 132 KTS AT 061200Z CIMSS AIDT: 131 KTS AT 061200Z CIMSS D-MINT: 139 KTS AT 060822Z CIMSS D-PRINT: 141 KTS AT 061200Z FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: FAVORABLE VWS: 10-15 KTS SST: 29-30 CELSIUS OUTFLOW: MODERATE WESTWARD ANALYSIS CONFIDENCE: INITIAL POSITION: HIGH INITIAL INTENSITY: MEDIUM INITIAL WIND RADII: MEDIUM 3. FORECAST REASONING. SIGNIFICANT FORECAST CHANGES: THERE ARE NO SIGNIFICANT CHANGES TO THE FORECAST FROM THE PREVIOUS WARNING. FORECAST DISCUSSION: STY BAVI WILL MAINTAIN A WEST-NORTHWESTWARD TRAJECTORY WITH A STEADY FORWARD MOTION OF 14 KTS UNDER THE STEERING INFLUENCE OF THE STR FOR THE NEXT 48 HOURS. BY TAU 60, THE SYSTEM WILL DECELERATE SLIGHTLY AND VEER TOWARDS THE NORTHWEST AS IT REACHES THE SOUTHWESTERN PERIPHERY OF THE STEERING RIDGE. SUBSEQUENTLY, THE STR WILL BUILD TO THE EAST, CAUSING THE SYSTEM TO ACCELERATE ALONG ITS NORTHWESTERN TRACK. ON THIS TRAJECTORY, THE STORM CENTER WILL PASS NEAR THE NORTHEASTERN TIP OF TAIWAN BEFORE MAKING LANDFALL OVER CENTRAL CHINA. THE ENVIRONMENT WILL SUPPORT THE STORM'S INTENSITY IN THE NEAR TERM, WITH LOW TO MODERATE VWS PERSISTING FOR THE NEXT 12 HOURS. HOWEVER, AN UPPER-LEVEL RIDGE WILL BUILD TO THE NORTH AND INDUCE STRONGER EASTERLY SHEAR. ALTHOUGH THE TYPHOON WILL CONTINUE TO TRAVEL OVER WARM SST AND HIGH OHC, THIS INCREASED SHEAR WILL TRIGGER A GRADUAL WEAKENING TREND THROUGH TAU 96. FURTHERMORE, POTENTIAL ERC EVENTS, AS DEPICTED BY HAFS-A, INTRODUCE COMPLEXITY AND REDUCE OVERALL CONFIDENCE IN THE INTENSITY FORECAST. BETWEEN TAU 96 AND TAU 120, THE MOUNTAINOUS TERRAIN OF NORTHERN TAIWAN WILL SEVERELY DISRUPT THE STORM'S EXPANSIVE CIRCULATION, LEADING TO RAPID WEAKENING UP TO AND THROUGH LANDFALL AT TAU 120. STY BAVI WILL MAINTAIN A VERY LARGE WIND FIELD UNTIL ITS DEMISE, AND GALE-FORCE WINDS WILL COMPLETELY ENVELOPE BOTH TAIWAN AND OKINAWA DURING ITS PASSAGE. MODEL DISCUSSION: WITH THE EXCEPTION OF NAVGEM, THE MODEL GUIDANCE IS IN TIGHT AGREEMENT THROUGH TAU 48. THE ALONG-TRACK SPREAD IS VERY LOW THROUGHOUT THE ENTIRE FORECAST PERIOD, MEASURING 120 NM AT TAU 120. IN CONTRAST, THE CROSS-TRACK SPREAD EXPANDS SIGNIFICANTLY IN THE EXTENDED PERIOD, REACHING 220 NM AT TAU 96 AND 340 NM AT TAU 120. NAVGEM REPRESENTS THE NORTHERNMOST OUTLIER AMONG THE GUIDANCE, BRINGING THE SYSTEM TO WITHIN 85 NM OF OKINAWA. THE AI TRACKERS, WHICH HAVE SKEWED POLEWARD AND NEARER TO THE RYUKYU ISLANDS, HAVE NOTABLY SHIFTED SLIGHTLY EQUATORWARD. THIS ADJUSTMENT BRINGS THE AI GUIDANCE IN SLIGHTLY CLOSER ALIGNMENT WITH THE PHYSICS-BASED MODELS, WHICH ARE TIGHTLY PACKED AND HAVE CONSISTENTLY PREDICTED A CLOSE APPROACH TO TAIWAN. THE JTWC FORECAST TRACK IS POSITIONED ALONG THE MULTI-MODEL CONSENSUS THROUGH TAU 72 WITH HIGH CONFIDENCE. BEYOND THAT POINT, THE TRACK HEDGES SLIGHTLY POLEWARD OF THE CONSENSUS AT TAU 96 AND TAU 120 WITH MEDIUM CONFIDENCE. THE MAJORITY OF THE INTENSITY AIDS DEPICT A SLOW TO GRADUAL WEAKENING TREND UP TO TAU 96. HWRF IS A MAJOR OUTLIER AND DEPICTS STEADY INTENSIFICATION UP TO 170 KTS AT TAU 72, WHICH WAS DEEMED UNREALISTIC. COAMPS-TC MAINTAINS THE HIGH INTENSITY THROUGH TAU 96. THE JTWC INTENSITY FORECAST IS SET CLOSE TO THE HAFS-A AND THE EXPERIMENTAL GOOGLE DEEPMIND SOLUTIONS, WHICH DEPICT A GRADUAL RATE OF WEAKENING FOR THE FIRST FOUR DAYS. THE INTENSITY AIDS UNANIMOUSLY SHOW RAPID WEAKENING FROM TAU 96 TO TAU 120 AS THE DISRUPTIVE EFFECTS OF LAND INTERACTION TAKE FULL EFFECT. FORECAST CONFIDENCE: TRACK 00-72 HR: HIGH TRACK 72-120 HR: MEDIUM INTENSITY 00-72 HR: MEDIUM INTENSITY 72-120 HR: MEDIUM// NNNN