WDPN31 PGTW 302100 MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI// SUBJ/PROGNOSTIC REASONING FOR SUPER TYPHOON 12W (HINNAMNOR) WARNING NR 011// RMKS/ 1. FOR METEOROLOGISTS. 2. 6 HOUR SUMMARY AND ANALYSIS. SUMMARY: INITIAL POSITION: 26.3N 131.9E INITIAL INTENSITY: 140 KTS GEOGRAPHIC REFERENCE: 221 NM EAST OF KADENA AB MOVEMENT PAST 6 HOURS: WESTWARD AT 16 KTS SIGNIFICANT WAVE HEIGHT: 50 FEET SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION: ANIMATED ENHANCED INFRARED (EIR) SATELLITE IMAGERY DEPICTS A WELL DEFINED SUPER TYPHOON, WITH A SYMMETRIC CENTRAL DENSE OVERCAST SURROUNDING A 9NM WIDE CLEAR EYE WITH EYE TEMPERATURES AROUND 18-20C. A 301315Z GMI 89GHZ MICROWAVE IMAGE SHOWED A SMALL INNER CORE SURROUNDING THE EYE, WITH A MOAT AND A NASCENT SECONDARY EYEWALL BEGINNING TO FORM. JAPANESE RADAR DATA AT THE 1800Z HOUR CONFIRMS A STRONG INNER-EYEWALL WITH A RAGGED AND WEAK SECONDARY EYEWALL CONTINUING TO DEVELOP, PARTICULARLY ON THE WESTERN SIDE OF THE CIRCULATION, MARKING THE ONSET OF ANOTHER EYEWALL REPLACEMENT CYCLE (ERC). THE INITIAL POSITION IS ASSESSED WITH HIGH CONFIDENCE BASED ON THE 9NM WIDE EYE AND THE RADAR DATA. THE INITIAL INTENSITY IS ASSESSED AT 140 KNOTS, SLIGHTLY HIGHER THAN THE SUBJECTIVE AND OBJECTIVE FIXES, BASED ON CONSISTENT SIX HOUR TRENDS IN THE SUBJECTIVE FIXES AND OVERALL STEADY STRUCTURE. THE EXTENT OF THE WIND RADII HAS BEEN SIGNIFICANTLY REDUCED BASED ON A 301240Z ASCAT PASS AS WELL AS OBSERVATIONAL DATA FROM MINAMI DAITO, JUST SOUTHWEST OF STY 12W, REPORTING WINDS AROUND 25 KNOTS. INITIAL WIND RADII BASIS: 301240Z SCATTEROMETER DATA CURRENT STEERING MECHANISM: SOUTHWESTERN PERIPHERY OF A DEEP-LAYER SUBTROPICAL RIDGE (STR) CENTERED TO THE NORTHEAST. AGENCY DVORAK AND AUTOMATED FIXES: PGTW: T7.0 - 140 KTS RJTD: T7.0 - 140 KTS KNES: T6.5 - 127 KTS CIMSS SATCON: 136 KTS AT 301625Z CIMSS ADT: 130 KTS AT 301810Z FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: FAVORABLE VWS: 5-10 KTS SST: 30-31 CELSIUS OUTFLOW: STRONG RADIAL OTHER FACTORS: MODERATE EQUATORWARD OUTFLOW INTO A TROPICAL UPPER TROPOSPHERIC TROUGH (TUTT) CELL FAR TO THE SOUTHEAST. ANALYSIS CONFIDENCE: INITIAL POSITION: HIGH INITIAL INTENSITY: HIGH INITIAL WIND RADII: HIGH 3. FORECAST REASONING. SIGNIFICANT FORECAST CHANGES: THERE ARE NO SIGNIFICANT CHANGES TO THE FORECAST FROM THE PREVIOUS WARNING. FORECAST DISCUSSION: STY 12W HAS TRACKED JUST A SHADE SOUTH OF DUE WEST OVER THE PAST SIX HOURS, AND HAS REACHED AN INFLECTION POINT IN THE STEERING PATTERN. THE SYSTEM IS CURRENTLY BEING STEERED ALONG THE SOUTHWESTERN SIDE OF A STR TO THE NORTHEAST, BUT THE PASSAGE OF A SHORTWAVE TROUGH TO THE NORTH HAS BROKEN THE RIDGE, WITH A COL REGION DEVELOPING IN THE DEEP-LAYER MEAN FLOW JUST WEST OF KYUSHU. HENCE, THE SYSTEM WILL LIKELY SLOW A BIT BEFORE ANOTHER STR TO THE WEST PICKS UP THE BATON AS THE PRIMARY STEERING MECHANISM AND THE SYSTEM WILL START TO TURN MORE SOUTHWESTWARD OVER THE NEXT FEW HOURS AS THE RIDGE TO THE WEST TAKES OVER. AN ADDITIONAL FACTOR IN THE FORECAST TRACK OVER THE NEXT 48 HOURS IS A POTENTIAL BINARY INTERACTION WITH TD 13W, DEVELOPING APROXIMATELY 400NM TO THE SOUTH. AS TD 13W MOVES NORTH-NORTHWESTWARD ALONG THE EASTERN PERIPHERY OF STY 12W, IT WILL LIKELY PULL STY 12W ONTO A SLIGHTLY MORE SOUTHWARD TRAJECTORY, THOUGH THE STRENGTH OF THIS INTERACTION IS HIGHLY UNCERTAIN DUE TO THE RELATIVELY WEAKNESS OF TD 13W. BY TAU 36 THE SYSTEM WILL MOVE INTO A COMPETING STEERING ENVIRONMENT, TRAPPED BETWEEN AND STR TO THE WEST AND NORTHEAST AND A NEAR EQUATORIAL RIDGE (NER) TO THE SOUTH, LEADING TO QUASI-STATIONARY MOTION FROM TAU 36 TO 72. BY TAU 72 THE APPROACH OF A MAJOR SHORTWAVE TROUGH WITH STRONG MID-LATITUDE DYNAMIC FORCING WILL ERODE THE RIDGE TO THE WEST AND ALLOW A BUILDING STR TO THE EAST TO EJECT 12W OUT OF ITS COCOON AND THE SYSTEM WILL BEGIN TRANSITING NORTHWARD THROUGH THE REMAINDER OF THE FORECAST PERIOD. A SECONDARY CPA TO OKINAWA OF APPROXIMATELY 185NM IS ANTICIPATED AROUND 041600Z AS THE SYSTEM MOVES NORTH IN THE EAST CHINA SEA. WHILE ENVIRONMENTAL CONDITIONS REMAIN VERY FAVORABLE, INTENSITY HAS LIKELY PEAKED OVERNIGHT, WITH THE ANTICIPATED ERC EXPECTED TO WEAKEN THE SYSTEM DOWN TO 130 KNOTS WITHIN THE NEXT 12 HOURS. AS THE SYSTEM STALLS SOUTH OF THE RYUKUS, SIGNIFICANT UPWELLING IS ANTICPATED, COUPLED WITH AN INCREASE IN VWS IN FORECAST TO RESULT IN A SHARP DECREASE IN INTENSITY, DOWN TO 95 KNOTS BY TAU 72. HOWEVER, REINTENSIFICATION IS FORECAST AFTER THE SYSTEM KICKS OUT TO THE NORTH AND MOVES BACK OVER WARMER WATERS, SHEAR DECREASES AND IT BEGINS TO TAP INTO STRONG POLEWARD OUTFLOW AHEAD OF THE APPROACHING TROUGH. MODEL DISCUSSION: DETERMINISTIC AND ENSEMBLE GUIDANCE REMAINS IN VERY GOOD AGREEMENT IN THE SHORT-TERM, WITH MINIMAL SPREAD ACROSS THE GUIDANCE THROUGH TAU 36. A DIFFERENT STORY TAKES HOLD AFTER THIS POINT HOWEVER, WITH SIGNIFICANT DISAGREEMENT BETWEEN THE CONSENSUS MEMBERS, WITH TWO DISTINCT GROUPINGS. THE FIRST GROUP CONSISTING OF GFS, ECMWF AND THEIR ENSEMBLE MEANS, HWRF AND THE JGSM, TURN THE SYSTEM SHARPLY NORTH TO NORTH-NORTHEASTWARD AFTER TAU 72, WITH THE ECMWF SHOWING THE SHARPEST INSIDE CURVE. MEANWHILE THE SECOND GROUPING CONSISTING OF NAVGEM, EGRR, UKMET ENSEMBLE AND THE GALWEM TAKE THE SYSTEM FURTHER SOUTH BEFORE TAKING A GRADUAL POLEWARD TURN, TAKING THE SYSTEM OVER TAIWAN. THE JTWC TRACK REMAINS CONSISTENT WITH THE PREVIOUS FORECAST, AND LIES ON THE NORTHERN EDGE OF THE ENVELOPE WITH HIGH CONFIDENCE IN THE SHORT-TERM FORECAST. THE LONGER RANGE FORECAST LIES NORTH AND EAST OF THE CONSENSUS MEAN, AS IT IS PULLED TO FAR SOUTH AND WEST BY THE SECOND GROUPING OF MODELS ABOVE, HEDGED MORE TOWARDS THE GFS AND ECMWF, WITH LOW CONFIDENCE. INTENSITY GUIDANCE IS IN FAIRLY GOOD AGREEMENT THROUGH THE FORECAST PERIOD, THOUGH THE ULTIMATE SECONDARY PEAK IS DEPENDENT UPON THE AMOUNT OF WEAKENING EXPERIENCED IN THE MID-TERM, THUS CONFIDENCE IS MEDIUM, TRENDING LOW. FORECAST CONFIDENCE: TRACK 0 - 72 HR: MEDIUM TRACK 72-120 HR: LOW INTENSITY 0 - 72 HR: MEDIUM INTENSITY 72-120 HR: LOW// NNNN