WDPN31 PGTW 040900 MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI// SUBJ/PROGNOSTIC REASONING FOR TYPHOON 12W (DOLPHIN) WARNING NR 034// RMKS/ 1. FOR METEOROLOGISTS. 2. 6 HOUR SUMMARY AND ANALYSIS. SUMMARY: INITIAL POSITION: 25.3N 141.9E INITIAL INTENSITY: 115 KTS GEOGRAPHIC REFERENCE: 44 NM NORTHEAST OF IWO TO MOVEMENT PAST 6 HOURS: WESTWARD AT 11 KTS SIGNIFICANT WAVE HEIGHT: 52 FEET SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION: TYPHOON (TY) 12W (DOLPHIN) HAS UNDERGONE A REMARKABLE TRANSFORMATION OVER THE PAST 6-12 HOURS, WITH THE INNER CORE EXPERIENCING A REINCARNATION OF SORTS. A SERIES OF MICROWAVE IMAGES BETWEEN 032200Z AND 040413Z, INCLUDING A GMI AND AMSR2 PASS, REVEALED THAT THE OUTER RING OF CONVECTION LOCATED APPROXIMATELY 100NM DISTANT FROM THE CENTER HAS BEGUN TO FRAGMENT AND WEAKEN, PARTICULARLY ON THE WESTERN SIDE. THE OVERALL WEAKENING OF THE OUTER RING OF CONVECTION HAS ALLOWED THE INNER CORE TO STEADILY CONSOLIDATE, WITH THE 040413Z AMSR2 89H MICROWAVE IMAGE DEPICTING A FULLY ENCLOSED INNER EYEWALL. ANIMATED MULTISPECTRAL SATELLITE IMAGERY (MSI) DEPICTS A 15NM WIDE, CLOUD-FREE EYE PASSING DIRECTLY OVER THE ISLAND OF NORTH IWO TO. EYE TEMPERATURES HAVE INCREASED RAPIDLY OVER THE PAST TWO HOURS AND ARE CURRENTLY ESTIMATED AT 14C. CLOUD TOP TEMPERATURES HAVE ALSO COOLED SIGNIFICANTLY OVER THE PAST 12 HOURS BUT ARE NOW BEGINNING TO LEVEL OFF AND EVEN WARM SLIGHTLY. ANIMATED WATER VAPOR IMAGERY DEPICTS VIGOROUS RADIAL OUTFLOW AS WELL AS A STRONG POLEWARD OUTFLOW CHANNEL INTO THE BASE OF AN UPPER-LEVEL TROUGH WHICH EXTENDS FROM NORTH OF TY 12W FAR OFF TO THE NORTHEAST. THE SYSTEM HAS EXHIBITED SOME TROCHOIDAL MOTION OVER THE PAST SIX HOURS, BUT IN THE LAST THREE HOURS HAS STABILIZED ONTO A DUE WESTWARD TRACK. THE INITIAL POSITION IS ASSESSED WITH HIGH CONFIDENCE BASED ON THE EYE FEATURE IN THE MSI AND EXTRAPOLATION OF THE MICROWAVE EYE IN THE AMSR2 IMAGE NOTED ABOVE. THE INITIAL INTENSITY IS ASSESSED WITH MEDIUM CONFIDENCE, BIASED TOWARDS THE T6.0 DVORAK CURRENT INTENSITY ESTIMATES FROM PGTW, RJTD AND RCTP AS WELL AS THE 117 KNOT ESTIMATE FROM CIMSS ADT. ENVIRONMENTAL CONDITIONS ARE FAVORABLE. THE SYSTEM IS MOVING OVER THE WARMEST WATERS IN THE WESTERN PACIFIC, THOUGH THE DEPTH OF THE WARM LAYER IS RELATIVELY SHALLOW, GENERATING LOW OHC. UPPER-LEVEL OUTFLOW REMAINS STRONG AND DEEP-LAYER SHEAR IS LOW, THOUGH MODEL-BASED SOUNDINGS SUGGEST A SLIGHTLY HIGHER AMOUNT OF NORTHWESTERLY SHEAR IN THE UPPERLEVELS OF THE ATMOSPHERE, WHICH SEEMS TO BE EVIDENT IN THE OVERALL SATELLITE APPEARANCE. INITIAL WIND RADII BASIS: SCATTEROMETER DATA CURRENT STEERING MECHANISM: SOUTHEASTERN FLANK OF A DEEP-LAYER SUBTROPICAL RIDGE (STR) CENTERED IN THE SEA OF JAPAN. AGENCY DVORAK AND AUTOMATED FIXES: PGTW: T6.0 - 115 KTS RJTD: T6.0 - 115 KTS RCTP: T6.0 - 115 KTS KNES: T5.5 - 102 KTS CIMSS SATCON: 100 KTS AT 040530Z CIMSS ADT: 117 KTS AT 040600Z CIMSS AIDT: 109 KTS AT 040600Z CIMSS D-MINT: 104 KTS AT 040413Z CIMSS D-PRINT: 90 KTS AT 040640Z FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: FAVORABLE VWS: 5-10 KTS SST: 29-30 CELSIUS OUTFLOW: STRONG RADIAL OTHER FACTORS: SLIGHTLY ELEVATED NORTHWESTERLY SHEAR IN THE 400-150MB LEVEL; UPWELLING OF COOLER SUBSURFACE WATERS. ANALYSIS CONFIDENCE: INITIAL POSITION: HIGH INITIAL INTENSITY: MEDIUM INITIAL WIND RADII: HIGH 3. FORECAST REASONING. SIGNIFICANT FORECAST CHANGES: THERE ARE NO SIGNIFICANT CHANGES TO THE FORECAST FROM THE PREVIOUS WARNING. FORECAST DISCUSSION: TY 12W IS FORECAST TO CONTINUE TRACKING WESTWARD AT A NEARLY CONSTANT SPEED, ALONG THE SOUTHERN FLANK OF A DEEP-LAYER STR, CENTERED ANOMALOUSLY IN THE SEA OF JAPAN. THE SYSTEM WILL BEGIN TO SLOW DOWN AFTER TAU 60, AS A STRONG UPPER-LEVEL TROUGH MOVES INTO NORTHEASTERN MANCHURIA AND BEGINS TO ERODE THE STR FROM THE WEST. BY TAU 72 TO TAU 84, THE TROUGH WILL HAVE ERODED THE STR ENOUGH FOR A WEAKNESS TO DEVELOP OVER THE KOREAN PENINSULA, AND THIS WEAKNESS WILL HAVE A SIGNIFICANT IMPACT ON THE LONG-RANGE FORECAST FOR TY 12W. ALL FOUR PRIMARY GLOBAL MODELS DEPICT THE WEAKNESS WITH THE SAME ORIENTATION, STRENGTH AND TIMING. HOWEVER, THE MODELS ARE BEGINNING TO SHOW MAJOR DIFFERENCES IN THE OVERALL IMPACT ON TY 12W. THE GFS HAS SHIFTED AGGRESSIVELY SINCE THE PREVIOUS RUN, NOW SHOWING THE SYSTEM STALLING PRIOR TO REACHING OKINAWA THEN TURNING NORTH BY TAU 120, JOINING THE NAVGEM AND JGSM MODELS IN THIS DEPICTION. THE ECMWF AND THE MAJORITY OF THE ENSEMBLES SUPPORT A STEADY WESTWARD, ALBEIT WITH SIGNIFICANT SLOWING, THROUGH THE END OF THE FORECAST PERIOD. THE NAVGEM AND JGSM HAVE KNOWN POLEWARD BIASES IN THESE SCENARIOS, WHERE AS THE GFS EXHIBITS LESS OF A BIAS. HOWEVER, THE PREPONDERANCE OF THE MODELS (DETERMINISTIC, ENSEMBLE AND AI) SUPPORT PERSISTENCE OF THE WESTWARD TRACK THROUGH TAU 120, AS THE WEAKNESS IN THE RIDGE DOES NOT APPEAR AT THIS TIME TO BE STRONG ENOUGH TO INFLUENCE TY 12W TO TRACK NORTHWARD AS PRONOUNCED AS. THE FORECAST CALLS FOR LANDFALL ON OKINAWA SHORTLY AFTER TAU 72. THOUGH SOMEWHAT DELAYED, THE SYSTEM HAS COMPLETED THE FOURTH EYEWALL REPLACEMENT CYCLE (ERC) AND HAS REINTENSIFIED WITH A RENEWED VIGOR. THE SYSTEM IS EXPECTED TO BRIEFLY REACH 120 KNOTS WITHIN THE NEXT FEW HOURS, BUT THIS FIFTH PEAK INTENSITY WILL BE SHORT-LIVED. ALREADY, THE EYE IS SHOWING SIGNS OF ENLARGING AND THE MSI AND INFRARED IMAGERY SUGGEST A LARGER EYEWALL IS BEGINNING TO FORM. ADDITIONALLY, DUE TO THE EXTREMELY LARGE SIZE OF THE SYSTEM, OCEANIC UPWELLING IS OCCURRING ACROSS A WIDE REGION, RESULTING IN A GENERAL COOLING OF SSTS ALONG THE TRACK. ALL MESOSCALE MODELS SUPPORT A SLOWLY BUT STEADILY ENLARGING INNER CORE AS THE SYSTEM PROGRESSES WESTWARD, SUPPORTING A SLOW STEP-WISE WEAKENING, AS DEPICTED IN THE JTWC FORECAST. HOWEVER, THE SYSTEM IS EXPECTED TO REMAIN A SIGNIFICANT TYPHOON AS IT CROSSES THE RYUKYU ISLANDS AND IMPACTS OKINAWA. MODEL DISCUSSION: UP TO TAU 60, THE TRACK CONSENSUS, AS WELL AS THE ENSEMBLE MEANS, ARE TIGHTLY CONSTRAINED TO A VERY NARROW ENVELOPE, WITH MINIMAL CROSS- OR ALONG-TRACK UNCERTAINTY. THE JTWC FORECAST IS PLACED NEAR THE MULTI-MODEL CONSENSUS MEAN AS WELL AS THE AI CONSENSUS MEAN WITH HIGH CONFIDENCE. AFTER TAU 60, THE GUIDANCE BEGINS TO DIVERGE RAPIDLY. AS DISCUSSED ABOVE, THE GFS, NAVGEM AND JGSM ALL DEPART FROM THE TIGHTLY CONSTRAINED MODEL ENVELOPE, INITIALLY MOVING SOUTHWESTWARD, SLOWING DOWN TO NEARLY QUASI-STATIONARY SPEEDS, AND THEN RAPIDLY TURN NORTHWARD AFTER TAU 72, ENDING UP BETWEEN AMAMI OSHIMA AND YAKUSHIMA BY TAU 120. THE REMAINDER OF THE DETERMINISTIC MODELS (ECMWF, GALWEM, UKMET), THE GEFS, AND ECENS ENSEMBLE MEANS, AS WELL AS ALL AVAILABLE AI MODEL TRACKERS, MOVE THE SYSTEM WESTWARD INTO THE EAST CHINA SEA, WITH STEADILY DECREASING SPEED. THE JTWC FORECAST IS PLACED NORTH OF THE ECMWF, BUT SOUTH OF THE GEFS AND ECENS MEANS, CLOSE TO THE AI CONSENSUS MEAN. THE JTWC EXPERIMENTAL SUPER ENSEMBLE SHOWS A TIGHT MEMBER ENVELOPE THROUGH TAU 72, WITH INCREASED MEMBER DISPERSION THEREAFTER, WITH A FOCUS ON A NORTHWARD TURN AFTER TAU 96. CONFIDENCE IN THE EXTENDED FORECAST IS MEDIUM IN LIGHT OF THE INCREASED UNCERTAINTY IN THE ENSEMBLE MEMBERS AND RECENT SHIFT IN SEVERAL OF THE MODEL TRACKERS. INTENSITY GUIDANCE IS FOR THE MOST PART IN GOOD AGREEMENT. THE ONLY MODEL SHOWING INTENSIFICATION IS CTCX, WHILE THE REMAINDER OF THE CONSENSUS DEPICTS A GRADUAL WEAKENING THROUGH THE FORECAST PERIOD, SUPPORTING THE JTWC FORECAST WITH MEDIUM CONFIDENCE. FORECAST CONFIDENCE: TRACK 00-72 HR: HIGH TRACK 72-120 HR: MEDIUM INTENSITY 00-72 HR: MEDIUM INTENSITY 72-120 HR: LOW// NNNN