WDPN32 PGTW 061500 MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI// SUBJ/PROGNOSTIC REASONING FOR TROPICAL STORM 06W (KHANUN) WARNING NR 042// RMKS/ 1. FOR METEOROLOGISTS. 2. 6 HOUR SUMMARY AND ANALYSIS. SUMMARY: INITIAL POSITION: 27.4N 130.6E INITIAL INTENSITY: 55 KTS GEOGRAPHIC REFERENCE: 345 NM SOUTH OF SASEBO, JAPAN MOVEMENT PAST 6 HOURS: SOUTHEASTWARD AT 05 KTS SIGNIFICANT WAVE HEIGHT: 34 FEET SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION: TROPICAL STORM (TS) 06W HAS MAINTAINED INTENSITY AT 55 KNOTS WITH A SLOW AND ERRATIC TRACK OVER THE PAST 18 HOURS DUE TO THE PRESENCE OF MULTIPLE MESOVORTICES ROTATING WITHIN A BROAD, EXPOSED CENTER. ANIMATED PROXYVIS SATELLITE IMAGERY AND ANIMATED RADAR IMAGERY SHOW PERSISTENT CONVECTIVE BANDING WRAPPING INTO A DEFINED LOW-LEVEL CIRCULATION CENTER (LLCC), WHICH SUPPORTS THE INITIAL POSITION WITH MEDIUM CONFIDENCE. A 060936Z GMI 37GHZ COLOR COMPOSITE MICROWAVE IMAGE SHOWS TIGHTLY-CURVED BANDING WRAPPING INTO A DEFINED LLCC AND ALSO SUPPORTS THE INITIAL POSITION. ENVIRONMENTAL CONDITIONS REMAIN MARGINALLY FAVORABLE WITH SIGNIFICANT DRY AIR IN THE MID- TO UPPER- LEVELS INDICATED IN THE RECENT KAGOSHIMA AND NAZE SOUNDINGS. HOWEVER, THE DEEP CONVECTIVE STRUCTURE HAS MAINTAINED DUE TO LOW VERTICAL WIND SHEAR (VWS), WARM SST (29C) AND MODERATE EQUATORWARD VENTING. THERE IS MEDIUM CONFIDENCE IN THE INITIAL INTENSITY BASED ON PERSISTENCE AND THE RJTD AND KNES CURRENT INTENSITY ESTIMATES OF 55 KNOTS. INITIAL WIND RADII BASIS: SCATTEROMETER DATA AND SURFACE OBSERVATIONS CURRENT STEERING MECHANISM: WEAK SUBTROPICAL RIDGE (STR) POSITIONED TO THE EAST AND NORTHEAST AGENCY DVORAK AND AUTOMATED FIXES: PGTW: T3.0 - 45 KTS RJTD: T3.5 - 55 KTS RCTP: T3.0 - 45 KTS KNES: T3.5 - 55 KTS CIMSS ADT: 37 KTS AT 061140Z FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: MARGINALLY FAVORABLE VWS: 5-10 KTS SST: 29-30 CELSIUS OUTFLOW: MODERATE EQUATORWARD OTHER FACTORS: DRY AIR ENTRAINMENT ANALYSIS CONFIDENCE: INITIAL POSITION: MEDIUM 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: TS 06W IS WOBBLING SLOWLY SOUTHEASTWARD ALONG THE NORTHWESTERN PERIPHERY OF THE WEAK STR AND IS EXPECTED TO SLOWLY TURN POLEWARD WITHIN THE NEXT 12 HOURS. TRACK SPEEDS REMAIN SLOW DUE TO A DEVELOPING TROPICAL DISTURBANCE TO THE EAST, WHICH IS DISRUPTING THE STR. THE SYSTEM'S SLOW TRACK MOTION IS RESULTING IN PERSISTENT HEAVY RAINBANDS AND GALE-FORCE WINDS SUSTAINING OVER OKINAWA. AFTER TAU 12, TS 06W WILL TURN NORTH-NORTHWESTWARD AND GRADUALLY INTENSIFY DUE PRIMARILY TO IMPROVING POLEWARD OUTFLOW TO A PEAK OF 65 TO 70 KNOTS BY TAU 72. AS THE LARGE (600NM DIAMETER) SYSTEM TRACKS PARALLEL TO THE WESTERN COAST OF KYUSHU, IT WILL GRADUALLY WEAKEN DUE TO FRICTIONAL EFFECTS WITH MORE SIGNIFICANT WEAKENING AS IT APPROACHES THE BUSAN REGION WITH LANDFALL ANTICIPATED NEAR TAU 84. AFTER TAU 84, TS KHANUN WILL TRACK ALONG THE EASTERN PORTION OF THE KOREAN PENINSULA AND BEGIN INTERACTING WITH THE LEADING EDGE OF A SUBTROPICAL SHORTWAVE TROUGH AND WEAK BAROCLINIC ZONE. DESPITE THE BAROCLINIC INFLUENCE, THE SYSTEM IS FORECAST TO DISSIPATE AS IT TRACKS INTO NORTH KOREA AND NORTHEAST CHINA. MODEL DISCUSSION: NUMERICAL MODEL GUIDANCE REMAINS IN FAIR AGREEMENT WITH A 165NM CROSS-TRACK SPREAD IN SOLUTIONS AT TAU 72 (NEAR SASEBO) DIVERGING TO 255NM AT TAU 84 (NEAR BUSAN). IN GENERAL, NUMERICAL GUIDANCE IS IN POOR AGREEMENT AFTER TAU 72 WITH LOW CONFIDENCE (HIGH UNCERTAINTY) IN THE JTWC FORECAST TRACK OVER THE KOREAN PENINSULA. THIS UNCERTAINTY IS ALSO REFLECTED IN THE 060600Z GEFS AND EPS PROBABILISTIC GUIDANCE. OVERALL, THERE IS MEDIUM CONFIDENCE IN THE JTWC INTENSITY FORECAST WITH THE 060000Z COAMPS-TC ENSEMBLE SHOWING AN 80 TO 100 PERCENT PROBABILITY OF REINTENSIFICATION THROUGH TAU 48. FORECAST CONFIDENCE: TRACK 0 - 72 HR: MEDIUM TRACK 72-120 HR: LOW INTENSITY 0 - 72 HR: MEDIUM INTENSITY 72-120 HR: MEDIUM// NNNN