WDPN31 PGTW 010900 MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI// SUBJ/PROGNOSTIC REASONING FOR TROPICAL STORM 06W (JANGMI) WARNING NR 021// RMKS/ 1. FOR METEOROLOGISTS. 2. 6 HOUR SUMMARY AND ANALYSIS. SUMMARY: INITIAL POSITION: 25.6N 127.4E INITIAL INTENSITY: 60 KTS GEOGRAPHIC REFERENCE: 58 NM SOUTH-SOUTHWEST OF KADENA AB MOVEMENT PAST 6 HOURS: NORTHWARD AT 12 KTS SIGNIFICANT WAVE HEIGHT: 35 FEET SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION: ANIMATED MULTISPECTRAL SATELLITE IMAGERY (MSI) DEPICTS A RAGGED, BROAD, AND INCREASINGLY CLOUD-FILLED LOW LEVEL CIRCULATION CENTER (LLCC), APPROXIMATELY 58NM SOUTH OF KADENA AIR BASE, OKINAWA. THE MSI AND A 010717Z SSMIS 37GHZ MICROWAVE IMAGE CONFIRM THAT MULTIPLE MESOVORTICES PERSIST ALONG THE INNER EDGE OF THE DEGRADED EYEWALL. THE MICROWAVE IMAGERY AND HIGH-RESOLUTION MODEL CROSS-SECTIONS VALIDATE THE PRESENCE OF MODERATE WESTERLY SHEAR, CONCURRENT WITH DRY MID-LEVEL SUBSIDENT AIR INTRUDING FROM THE WEST INTO THE SOUTHWESTERN FLANK, WHICH IS RAPIDLY DEGRADING THE SOUTHWESTERN EYEWALL AND CONVECTIVE CORE. ANIMATED WATER VAPOR IMAGERY DEPICTS ROBUST POLEWARD OUTFLOW FLOWING INTO THE RIGHT REAR ENTRANCE REGION OF A 100-KNOT- PLUS JET MAXIMUM OVER CENTRAL HONSHU, AUGMENTED BY A MODERATE EQUATORWARD OUTFLOW CHANNEL TO THE SOUTHEAST. THE ROBUST OUTFLOW SUSTAINS DEEP CONVECTION WITHIN THE EASTERN SEMICIRCLE AND SUPPORTS MAINTENANCE OF THE CURRENT INTENSITY. SURFACE OBSERVATIONS FROM NAHA AND KADENA AB INDICATE PEAK WIND SPEEDS OCCURRED BETWEEN 0000Z-0100Z ASSOCIATED WITH THE PASSAGE OF THE RADIUS OF MAXIMUM WINDS (RMW). CONCURRENTLY, CURRENT SURFACE WINDS HAVE DIMINISHED SIGNIFICANTLY AS THE WIND SPEED MINIMUM ASSOCIATED WITH THE CENTER OF TS 06W TRANSITS OVER THE STATIONS. PRESSURE READINGS CONTINUE TO DECLINE, WITH NAHA REPORTING 980.1MB AT 0810Z, VALIDATING THE INITIAL MSLP ESTIMATE OF 979MB WITH HIGH CONFIDENCE. THE INITIAL POSITION IS ASSESSED WITH HIGH CONFIDENCE, CONSTRAINED BY ANALYSIS OF THE MSI, THE AFOREMENTIONED MICROWAVE IMAGERY, AND JMA RADAR DATA. THE INITIAL INTENSITY IS ASSESSED WITH HIGH CONFIDENCE, DERIVED FROM A BLEND OF SUBJECTIVE AND OBJECTIVE INTENSITY ESTIMATES, SURFACE WIND OBSERVATIONS, AND EXTRAPOLATED SAR DATA. ENVIRONMENTAL CONDITIONS ARE MARGINAL, WITH RAPIDLY DECLINING SSTS AND DRY AIR ENTRAINMENT OFFSET BY ROBUST POLEWARD OUTFLOW AND LOW DEEP-LAYER VWS. INITIAL WIND RADII BASIS: PERSISTENCE CURRENT STEERING MECHANISM: TROPICAL STORM (TS) 06W IS CROSSING THE WESTERN AXIS OF THE SUBTROPICAL RIDGE (STR) CENTERED NEAR IWO TO. AGENCY DVORAK AND AUTOMATED FIXES: PGTW: T4.0 - 65 KTS RJTD: T3.5 - 55 KTS RCTP: T3.5 - 55 KTS KNES: T4.0 - 65 KTS CIMSS SATCON: 55 KTS AT 010500Z CIMSS AIDT: 57 KTS AT 010700Z CIMSS D-MINT: 59 KTS AT 010717Z CIMSS D-PRINT: 54 KTS AT 010700Z FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: MARGINAL VWS: 5-10 KTS SST: 26-27 CELSIUS OUTFLOW: STRONG POLEWARD AND EQUATORWARD OTHER FACTORS: DRY MID-LEVEL AIR AND ASSOCIATED SUBSIDENCE FLOWING INTO THE SOUTHWESTERN FLANK OF THE CIRCULATION. ANALYSIS CONFIDENCE: INITIAL POSITION: HIGH INITIAL INTENSITY: HIGH INITIAL WIND RADII: MEDIUM 3. FORECAST REASONING. SIGNIFICANT FORECAST CHANGES: THERE ARE NO SIGNIFICANT CHANGES TO THE FORECAST FROM THE PREVIOUS WARNING. FORECAST DISCUSSION: 06W (JANGMI) HAS BEEN DOWNGRADED TO A TROPICAL STORM (TS) DUE TO ONGOING DEGRADATION AS IT APPROACHES OKINAWA. THE SYSTEM HAS REACHED THE STR AXIS AND IS COMMENCING A NORTHEASTWARD RECURVATURE. THE CENTER OF TS 06W IS FORECAST TO MAKE IMMINENT LANDFALL OVER THE SOUTHERN TIP OF OKINAWA, SUBSEQUENTLY TRANSITING ALONG THE WESTERN FLANK OF THE ISLAND OVER THE NEXT FEW HOURS. THE SYSTEM WILL CONTINUE TO TRACK NORTHEASTWARD, PARALLELING THE NORTHERN RYUKYU CHAIN, AND PASSING JUST OFFSHORE OF THE SOUTHERN TIP OF KYUSHU BY TAU 24. A BRIEF LANDFALL ALONG THE SOUTHERNMOST POINT OF HONSHU, SOUTH OF KYOTO, IS PROJECTED NEAR TAU 36, AS THE SYSTEM ACCELERATES NORTHEASTWARD ALONG THE TIGHT STEERING GRADIENT ON THE NORTHWESTERN FLANK OF THE STR, WHICH IS FORECAST TO RETROGRADE SOUTHWESTWARD DURING THIS PERIOD. TS 06W WILL TRANSIT ACROSS THE SOUTHERN PORTION OF SAGAMI BAY AND THE APPROACHES TO TOKYO BAY, PRODUCING A CLOSEST POINT OF APPROACH (CPA) TO YOKOSUKA BY TAU 72. THE SYSTEM WILL THEN TRACK EAST-NORTHEASTWARD OVER OPEN OCEAN WHILE STEADILY DECELERATING WITHIN A GRADUALLY WEAKENING STEERING GRADIENT ON THE NORTHERN FLANK OF THE STR FAR TO THE SOUTH. REGARDING INTENSITY, COMPETING ENVIRONMENTAL PARAMETERS, SUCH AS ROBUST OUTFLOW, INCREASING SHEAR, AND DECLINING SSTS, WILL TEMPORARILY OFFSET ONE ANOTHER FOR THE NEXT 24-36 HOURS, RESULTING IN A GRADUAL, STEP-WISE DECAY. AFTER TAU 36, THE SYSTEM WILL WEAKEN AT A FASTER RATE AS IT BECOMES VERTICALLY DECOUPLED, OWING TO ENTRAINED DRY AIR AND VERTICAL WIND SHEAR OVERWHELMING THE STRONG POLEWARD OUTFLOW. THE SYSTEM IS FORECAST TO BEGIN EXTRATROPICAL TRANSITION (ETT) BETWEEN TAU 36 AND TAU 48, WITH COMPLETION OF ETT AS EARLY AS TAU 60. NOTWITHSTANDING A FULLY DECOUPLED, NEARLY EXTRATROPICAL STATE BY THE TIME IT TRANSITS NEAR YOKOSUKA, THE ASSOCIATED WIND FIELD IS PROJECTED TO REMAIN ROBUST AND EXPAND DURING THE TRANSITION PROCESS. MODEL DISCUSSION: THE CONSENSUS PACKAGE IS IN EXTREMELY TIGHT AGREEMENT THROUGH THE ENTIRE FORECAST PERIOD. CROSS-TRACK SPREAD IS 35NM OR LESS FROM TAU 12 TO TAU 72, INCREASING TO 100NM AT TAU 72. THE JTWC FORECAST TRACK IS PLACED NEAR THE MULTI-MODEL CONSENSUS MEAN WITH HIGH CONFIDENCE. INTENSITY GUIDANCE IS ALSO IN STRONG AGREEMENT, WITH NEARLY ALL MEMBERS OF THE CONSENSUS PACKAGE IN AGREEANCE ON A GRADUAL BUT STEADY WEAKENING TREND THROUGH THE FORECAST PERIOD. THE ONLY EXCEPTION IS THE SHIPS-GFS WHICH DEPICTS THE SYSTEM DISSIPATING WITHIN THE NEXT 48 HOURS. THE JTWC FORECAST IS PLACED NEAR THE CONSENSUS MEAN WITH HIGH CONFIDENCE. FORECAST CONFIDENCE: TRACK 00-72 HR: HIGH TRACK 72-120 HR: --- INTENSITY 00-72 HR: HIGH INTENSITY 72-120 HR: ---// NNNN