WDPN32 PGTW 010300 MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI// SUBJ/PROGNOSTIC REASONING FOR TYPHOON 06W (KHANUN) WARNING NR 020// RMKS/ 1. FOR METEOROLOGISTS. 2. 6 HOUR SUMMARY AND ANALYSIS. SUMMARY: INITIAL POSITION: 24.6N 129.4E INITIAL INTENSITY: 120 KTS GEOGRAPHIC REFERENCE: 143 NM SOUTHEAST OF KADENA AB MOVEMENT PAST 6 HOURS: WEST-NORTHWESTWARD AT 10 KTS SIGNIFICANT WAVE HEIGHT: 48 FEET SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION: AFTER A RECENT SHORT-TERM BOUGHT OF WEAKENING, TYPHOON (TY) 06W (KHANUN) HAS ONCE AGAIN EXHIBITED SIGNS OF SLIGHT INTENSIFICATION. DEEP CONVECTION HAS ONCE MORE FLARED UP AND ROTATED UPSHEAR, REESTABLISHING A SOLID EYEWALL ON THE NORTHWESTERN SIDE, WHERE PREVIOUS MICROWAVE IMAGERY SUGGESTED A FRAGMENTARY EYEWALL. WHILE HIGH-RESOLUTION MODEL CROSS-SECTIONS AND THE MOST RECENT SOUNDING FROM MINAMI DAITO JIMA STILL SHOW A WEDGE OF DRY AIR CENTERED AT ABOUT 300MB, THE FLARE UP OF CONVECTION ON THE NORTHERN SIDE HAS PUSHED BACK AGAINST THIS INTRUSION AND ALLOWED THE SYSTEM TO INTENSIFY. THE INITIAL POSITION IS ASSESSED WITH HIGH CONFIDENCE BASED ON A 25NM WIDE EYE IN THE VISIBLE AND INFRARED SATELLITE IMAGERY. THE INITIAL INTENSITY IS ASSESSED WITH MEDIUM CONFIDENCE, BASED ON THE OVERALL AGREEMENT OF BOTH OBJECTIVE AND SUBJECTIVE INTENSITY ESTIMATES INCLUDING THE DPRINT AND DMINT ESTIMATES OF 119 KNOTS AND 123 KNOTS RESPECTIVELY. HOWEVER, CONFIDENCE IS JUST MEDIUM IN LIGHT OF A SIGNIFICANT DIFFERENCE BETWEEN A 312129Z SMAP PASS SHOWING A MAXIMUM 1-MIN CONVERTED WIND OF 81 KNOTS AND A SAR PASS FROM 310914Z WITH A MAXIMUM OF 91 KNOTS. THE VERY LARGE DISCREPANCIES IN THE AVAILABLE INTENSITY ESTIMATES INTRODUCING A FAIR AMOUNT OF UNCERTAINTY IN THE INITIAL INTENSITY. THE SYSTEM HAS STARTED TO TRACK ON A MORE WEST-NORTHWEST (300 DEG VICE THE EARLIER 315 DEG), AS THE STEERING SHIFTS TO THE SUBTROPICAL RIDGE (STR) CENTERED OVER THE BOHAI GULF. THE OVERALL ENVIRONMENT REMAINS FAVORABLE, WITH LOW NORTHERLY SHEAR AND WARM SSTS THOUGH UPPER-LEVEL OUTFLOW IS A BIT LESS ROBUST THAN SEEN IN PREVIOUS ANALYSES, WITH THE SYSTEM STILL TAPPING INTO AN OUTFLOW CHANNEL INTO THE TUTT-CELL SOUTHWEST OF SHANGHAI. OTHERWISE OUTFLOW IS RESTRICTED TO RELATIVELY WEAK EQUATORWARD FLOW AND LOCALIZED RADIAL OUTFLOW IN THE VICINITY OF THE SYSTEM ITSELF. INITIAL WIND RADII BASIS: PERSISTENCE CURRENT STEERING MECHANISM: SOUTHERN PERIPHERY OF A DEEP-LAYER STR CENTERED OVER THE BOHAI GULF. AGENCY DVORAK AND AUTOMATED FIXES: PGTW: T6.0 - 115 KTS RJTD: T6.0 - 115 KTS KNES: T6.0 - 115 KTS CIMSS ADT: 118 KTS AT 010000Z FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: FAVORABLE VWS: 10-15 KTS SST: 29-30 CELSIUS OUTFLOW: MODERATE RADIAL OTHER FACTORS: WEAK OUTFLOW CHANNEL INTO A TUTT-CELL SOUTHWEST OF SHANGHAI; UPPER-LEVEL DRY AIR INTRUSION. ANALYSIS CONFIDENCE: INITIAL POSITION: HIGH INITIAL INTENSITY: MEDIUM INITIAL WIND RADII: LOW 3. FORECAST REASONING. SIGNIFICANT FORECAST CHANGES: THERE ARE NO SIGNIFICANT CHANGES TO THE FORECAST FROM THE PREVIOUS WARNING. FORECAST DISCUSSION: TY KHANUN HAS STARTED TO BEND ONTO A MORE WEST-NORTHWESTWARD TRACK NOW THAT THE PRIMARY STEERING MECHANISM HAS SHIFTED OVER TO THE DEEP-LAYER STR TO THE NORTH. THIS GENERAL MOTION IS EXPECTED TO CONTINUE THROUGH THE FIRST 48 HOURS OF THE FORECAST, THOUGH TRACK SPEEDS ARE EXPECTED TO BEGIN TO SLOW DOWN AFTER TAU 24 AS THE UPPER-LEVEL STEERING PATTERN BEGINS TO WEAKEN. AFTER ROUGHLY TAU 36, THE STR TO THE NORTH WILL SLIDE TO THE SOUTHWEST, WHILE SIMULTANEOUSLY A NEAR EQUATORIAL RIDGE (NER) BUILDS IN TO THE SOUTHEAST AND THE STR TO THE EAST REMAINS FIRMLY ENTRENCHED TO THE EAST OF JAPAN, TRAPPING TY 06W IN THE MIDDLE OF A WEAK AND COMPETING STEERING PATTERN. AS A RESULT, BY TAU 48, TY 06W WILL BECOME QUASI-STATIONARY AND MEANDERING ERRATICALLY IN THE CENTRAL PORTION OF THE EAST CHINA SEA. BY TAU 96 THE SYSTEM WILL BEGIN TO SLOWLY TRACK NORTHEASTWARD AS THE NER TO THE SOUTH ASSUMES THE DOMINATE STEERING ROLE. WHILE THE FORECAST TRACK CALLS FOR A TURN TO THE NORTHEAST, IT MUST BE REITERATED THAT TRACK SPEEDS ARE VERY LOW, LESS THAN 3 KNOTS FOR THE BULK OF FORECAST AFTER TAU 48, AND ERRATIC AND HIGHLY UNCERTAIN TRACK MOTIONS SHOULD BE ANTICIPATED. TY 06W HAS LIKELY REACHED PEAK INTENSITY AND IS EXPECTED TO MAINTAIN ITS CURRENTLY INTENSITY FOR THE NEXT 6 TO 12 HOURS AS IT PASSES TO THE SOUTHWEST OF OKINAWA. AFTER PASSING OKINAWA THE SYSTEM WILL BEGIN A GRADUAL WEAKENING TREND DUE TO REDUCED OUTFLOW ALOFT, PERSISTENT DRY AIR INTRUSION FROM THE NORTH AND A MODEST INCREASE IN SHEAR. AS THE SYSTEM BECOMES QUASI-STATIONARY AROUND TAU 48, THE SYSTEM GENERATE SIGNIFICANT UPWELLING, WITH THE HAFS-A DEPICTING SST REDUCTIONS ON THE ORDER OF 4C OR MORE IN THE EAST CHINA SEA, LEADING TO A RAPID WEAKENING TREND AFTER TAU 48. MODEL DISCUSSION: DETERMINISTIC TRACK GUIDANCE IS IN GOOD CROSS-TRACK AGREEMENT THROUGH THE FIRST 48 HOURS OF THE FORECAST, THOUGH ALONG-TRACK SPREAD INCREASES SHARPLY AFTER TAU 48 AS THE MODELS DISAGREE ON THE TRACK SPEEDS AND HOW FAR WEST THE SYSTEM REACHES BEFORE TURNING BACK TO THE EAST. THE UKMET AND UKMET ENSEMBLE CONTINUE TO TRACK THE SYSTEM INTO EASTERN CHINA, WHILE THE REMAINDER OF THE CONSENSUS MEMBERS INDICATE A SHARP TURN BACK TO THE EAST-NORTHEAST BEGINNING BY TAU 72. THE HAFS-A, JGSM, AND ECMWF TAKE THE SYSTEM A BIT FURTHER WEST (AROUND 123E) BY TAU 72, WHILE THE GFS AND GEFS BEGIN FURTHER EAST. HOWEVER, BY TAU 120, THE ECMWF, GFS, NAVGEM AND THEIR ENSEMBLE MEANS COME INTO CONCURRENCE ON A REACHING A POSITION WEST OF AMAMI OSHIMA. DISCOUNTING THE UKMET MODELS, THE CONSENSUS ENVELOPE REACHES 225NM BY TAU 120. ENSEMBLE GUIDANCE DISPLAYS VERY HIGH UNCERTAINTY, WITH A WIDE SPREAD IN THE ENSEMBLE TRACK MEMBERS, PARTICULARLY AFTER TAU 96, LENDING LOW CONFIDENCE IN THE JTWC FORECAST AFTER TAU 48. INTENSITY GUIDANCE IS IN FAIRLY GOOD AGREEMENT, WITH THE JTWC FORECAST LYING ON THE UPPER END OF THE GUIDANCE ENVELOPE THROUGH THE FORECAST PERIOD WITH MEDIUM CONFIDENCE IN THE EARLY PORTION OF THE FORECAST AND LOW CONFIDENCE THEREAFTER DUE TO THE LARGE UNCERTAINTIES IN THE AMOUNT AND STRENGTH OF THE UPWELLING AND THE IMPACT THAT WILL HAVE ON THE INTENSITY. FORECAST CONFIDENCE: TRACK 0 - 72 HR: HIGH TRACK 72-120 HR: LOW INTENSITY 0 - 72 HR: MEDIUM INTENSITY 72-120 HR: LOW// NNNN