WDPN31 PGTW 060900 MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI// SUBJ/PROGNOSTIC REASONING FOR TYPHOON 12W (DOLPHIN) WARNING NR 042// RMKS/ 1. FOR METEOROLOGISTS. 2. 6 HOUR SUMMARY AND ANALYSIS. SUMMARY: INITIAL POSITION: 26.6N 132.6E INITIAL INTENSITY: 80 KTS GEOGRAPHIC REFERENCE: 258 NM EAST OF KADENA AB MOVEMENT PAST 6 HOURS: WEST-NORTHWESTWARD AT 10 KTS SIGNIFICANT WAVE HEIGHT: 40 FEET SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION: ANIMATED MULTISPECTRAL SATELLITE IMAGERY (MSI) DEPICTS TYPHOON (TY) 12W (DOLPHIN) AS AN EXPANSIVE SYSTEM, WITH A CLOUD SHIELD APPROXIMATELY 550 NM IN DIAMETER AND LOW-LEVEL INFLOW EXTENDING FAR BEYOND THAT. 12W ALSO SPORTS A CLOUD-FILLED PINHOLE EYE MEASURING APPROXIMATELY 10 NM IN DIAMETER SITUATED ASYMMETRICALLY INSIDE A TIGHTLY WOUND INNER CORE. A DRY SPIRAL EXTENDS FROM THE SOUTHERN PERIPHERY AND WRAPS INWARD, INDICATED IN ANIMATED INFRARED IMAGERY BY A DISTINCT LACK OF COLD CLOUD TOPS. THE 060646Z SSMIS IMAGE CONFIRMS THIS OBSERVATION BY REVEALING AN INNER CORE OF DEEP CONVECTION SURROUNDED BY A LARGE DRY MOAT THAT SEPARATES THE SECOND RING OF DEEP CONVECTION. ENVIRONMENTAL ANALYSIS INDICATES A FAVORABLE ENVIRONMENT, CHARACTERIZED BY LOW (10-15 KTS) VERTICAL WIND SHEAR (VWS), WARM (29-30 C) SEA SURFACE TEMPERATURES (SST), AND GOOD DIVERGENCE ALOFT. THE INITIAL POSITION IS PLACED WITH HIGH CONFIDENCE BASED ON THE PINHOLE EYE. THE INITIAL INTENSITY OF 80 KTS IS ASSESSED WITH MEDIUM CONFIDENCE BASED ON THE AGENCY DVORAK FIXES AND AUTOMATED CIMSS INTENSITY ESTIMATES LISTED BELOW. INITIAL WIND RADII BASIS: ADJUSTED THE NORTHERN 34 KT WIND RADII USING THE 060005Z AND 060144Z ASCAT PASSES. CURRENT STEERING MECHANISM: SOUTHERN FLANK OF A DEEP-LAYER SUBTROPICAL RIDGE (STR) CENTERED OVER THE SEA OF JAPAN AGENCY DVORAK AND AUTOMATED FIXES: PGTW: T4.5 - 77 KTS RJTD: T5.0 - 90 KTS RCTP: T4.0 - 65 KTS KNES: T5.0 - 90 KTS CIMSS SATCON: 84 KTS AT 060630Z CIMSS ADT: 82 KTS AT 060630Z CIMSS AIDT: 85 KTS AT 060630Z CIMSS D-MINT: 80 KTS AT 060646Z CIMSS D-PRINT: 75 KTS AT 060630Z FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: FAVORABLE VWS: 10-15 KTS SST: 29-30 CELSIUS OUTFLOW: MODERATE RADIAL 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: TY 12W IS FORECAST TO CONTINUE TRACKING GENERALLY WEST-NORTHWESTWARD THROUGH TAU 72 WHILE IT REMAINS UNDER THE STEERING INFLUENCE OF THE STR CENTERED OVER THE SEA OF JAPAN. A TROUGH PASSING OVER SIBERIA WILL WEAKEN THE STR, INDUCING SLOWER TRANSLATION SPEEDS BETWEEN TAU 24-72. AROUND TAU 72, THE STEERING RIDGE WILL REORIENT TO THE NORTHEAST OF THE SYSTEM AND BUILD, ACCELERATING TRACK SPEEDS AND INDUCING A NORTHWESTWARD CURVE. 12W IS FORECAST TO MAKE LANDFALL IN CHINA BETWEEN TAU 72-96. REGARDING INTENSITY, 12W IS FORECAST TO GENERALLY MAINTAIN INTENSITY THROUGH TAU 72. THE SYSTEM MAY MOMENTARILY SLIGHTLY INTENSIFY IN THE NEXT 12-24 HOURS AS IT TRACKS OVER A REGION OF SLIGHTLY ELEVATED OCEAN HEAT CONTENT ASSOCIATED WITH THE KUROSHIO CURRENT; HOWEVER, THE LARGE AND COMPLEX STRUCTURE OF THE STORM WILL PREVENT SIGNIFICANT INTENSIFICATION. DOLPHIN IS FORECAST TO WEAKEN SLIGHTLY LEADING UP TO LANDFALL IN CHINA, AS THE OCEAN HEAT CONTENT DROPS AND THE TRACK SPEED SLOWS, INTRODUCING COMPOUNDING EFFECTS FROM THE STORM'S COLD WAKE. AFTER LANDFALL, 12W IS EXPECTED TO DRASTICALLY WEAKEN OVER LAND AND FULLY DISSIPATE AFTER TAU 120. MODEL DISCUSSION: DETERMINISTIC MODEL TRACK GUIDANCE IS IN STRONG AGREEMENT THROUGH TAU 72, WITH THE EXCEPTION OF NAVGEM, WHICH HAS BEEN THE CONSISTENT AND SOLE EQUATORWARD OUTLIER. DISCOUNTING NAVGEM, THE JTWC TRACK FORECAST IS PLACED WITH HIGH CONFIDENCE FROM TAU 0-72. AFTER TAU 72, THE CROSS-TRACK SPREAD DRAMATICALLY INCREASES, AS MODELS DISAGREE ON THE ORIENTATION OF THE STEERING RIDGE, ULTIMATELY INFLUENCING WHERE ALONG THE COAST 12W WILL MAKE LANDFALL AND THE NORTHWESTWARD TURN THEREAFTER. ADDITIONALLY, TERRAIN INTERACTION WILL INTRODUCE ADDITIONAL UNCERTAINTY, AS THE STORM MAY BEHAVE ERRATICALLY AND UNPREDICTABLY OVER LAND. AS A RESULT, THE JTWC TRACK FORECAST IS PLACED WITH LOW CONFIDENCE FROM TAU 72-120. RELIABLE INTENSITY AIDS ARE IN GOOD AGREEMENT THAT 12W WILL GENERALLY MAINTAIN STRENGTH, WITH MINOR FLUCTUATIONS IN INTENSITY. THE JTWC INTENSITY FORECAST IS PLACED IN LINE WITH THE HAFS-A SOLUTION. AS A RESULT, THE JTWC TRACK FORECAST IS ASSESSED WITH OVERALL MEDIUM CONFIDENCE, WITH UNCERTAINTY STEMMING FROM THE POTENTIAL FOR A BRIEF REINTENSIFICATION IN THE NEAR-TERM FORECAST AND THE WEAKENING TREND POST-LANDFALL IN THE LATE-TERM FORECAST. FORECAST CONFIDENCE: TRACK 00-72 HR: HIGH TRACK 72-120 HR: LOW INTENSITY 00-72 HR: MEDIUM INTENSITY 72-120 HR: MEDIUM// NNNN