WDPN33 PGTW 171500 MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI// SUBJ/PROGNOSTIC REASONING FOR TYPHOON 16W (NANMADOL) WARNING NR 020// RMKS/ 1. FOR METEOROLOGISTS. 2. 6 HOUR SUMMARY AND ANALYSIS. SUMMARY: INITIAL POSITION: 27.6N 132.0E INITIAL INTENSITY: 125 KTS GEOGRAPHIC REFERENCE: 351 NM SOUTH-SOUTHEAST OF SASEBO, JAPAN MOVEMENT PAST 6 HOURS: NORTH-NORTHWESTWARD AT 10 KTS SIGNIFICANT WAVE HEIGHT: 48 FEET SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION: ANIMATED ENHANCED INFRARED (EIR) SATELLITE IMAGERY DEPICTS A LARGE, WELL DEFINED TYPHOON WITH SPIRAL BANDS OF DEEP CONVECTION WRAPPING INTO A 12NM EYE. DECENT MICROWAVE IMAGERY REMAINS ILLUSIVE, THE LAST FULL PASS WAS A 170732Z SSMIS 91GHZ MICROWAVE IMAGE WHICH INDICATED A SYMMETRIC CENTRAL CORE WITH A NEARLY COMPLETE SECONDARY EYE-WALL LIKE FEATURE. AS THE SYSTEM HAS PROGRESSED POLEWARD, 16W FORTUNATELY ENTERED RADAR RANGE WHICH SHOWS A SLIGHTLY FRAGMENTED WESTERN BANDING REGION WITH A TIGHT CORE AND SOMEWHAT INTACT SECONDARY EYEWALL. THE INITIAL POSITION IS PLACED WITH HIGH CONFIDENCE BASED ON EIR, SSMIS AND ANIMATED RADAR IMAGERY. THE INITIAL INTENSITY OF 125 KTS IS ASSESSED WITH MEDIUM CONFIDENCE BASED ON ALL AGENCY DVORAK INTENSITY ESTIMATES NOTING A DROP IN FINAL T NUMBER AS THE EYE COOLS AND CLOUD TOPS WARM, BUT MAINTAINING THE LISTED CURRENT INTENSITIES OF 115-127KTS WHICH IS CONSISTENT WITH CIMMS ADT AND THE JTWC FORECAST. INITIAL WIND RADII BASIS: PERSISTENCE CURRENT STEERING MECHANISM: SOUTHWESTERN PERIPHERY OF A DEEP-LAYER SUBTROPICAL RIDGE (STR) AGENCY DVORAK AND AUTOMATED FIXES: PGTW: T6.0 - 115 KTS RJTD: T6.0 - 115 KTS KNES: T6.5 - 127 KTS CIMSS ADT: 124 KTS AT 171140Z FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: MARGINAL VWS: 5-10 KTS SST: 29-30 CELSIUS OUTFLOW: MODERATE RADIAL 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: NO LONGER SUPER, TY 16W (NANMADOL) HAS ENTERED THE PREVIOUSLY FORECAST OCEAN HEAT CONTENT (OHC) COLD POOL LOITERING SOUTH OF KYUSHU. THE SYSTEM IS FORECAST TO CONTINUE TRACKING GENERALLY NORTH-NORTHWESTWARD UNDER THE STEERING INFLUENCE OF A STR TO THE NORTHEAST. THOUGH THE ENVIRONMENT IS CHARACTERIZED BY LOW VERTICAL WIND SHEAR (5-10KTS), WARM SST (29-30C) AND RADIAL OUTFLOW ALOFT, THE AFOREMENTIONED DECLINING OHC VALUES WILL RESULT IN GRADUAL LOSS IN INTENSITY THROUGH TAU 12. BY TAU 24, AN APPROACHING COLD FRONT AND ACCOMPANYING SHORTWAVE TROUGH WILL BEGIN TO BREAKDOWN THE STEERING RIDGE, AS A RESULT 16W WILL BEGIN TO EXECUTE A DRAMATIC NORTHEASTERLY TURN. AT THE SAME TIME, 16W WILL INCREASE ITS LAND INTERACTION AS IT PASSES SOUTH OF NAGASAKI AND DROPS BELOW 95KTS. BY TAU 36, NOW OVER KYUSHU, 16W WILL BEGIN TO SIGNIFICANTLY WEAKEN AS LAND INTERACTION WITH JAPAN AND SHEAR VALUES INCREASE. NEAR TAU 48, 16W DRASTICALLY INCREASES TRACK SPEEDS AND PROGRESSES ALONG THE FRONTAL BOUNDARY AS IT IS RIPPED APART BY INCREASING SHEAR VALUES AS WELL AS BY JAPAN ITSELF. SHORTLY AFTER TAU 48, AS THE SYSTEM PROGRESSES NORTH-NORTHEASTWARD, IT WILL CONTINUE TO WEAKEN AND ALSO BEGIN TO INTERACT WITH AND INTEGRATE INTO THE PASSING TROUGH THEREBY STARTING EXTRA-TROPICAL TRANSITION (ETT). AFTER TAU 72 THE REMNANTS OF 16W WILL EXIT INTO THE PACIFIC OCEAN AND COMPLETE ETT BY TAU 96. MODEL DISCUSSION: NUMERICAL MODEL GUIDANCE IS IN GOOD AGREEMENT THROUGH TAU 48 WITH A 100NM SPREAD IN SOLUTIONS. THIS QUICKLY DEVOLVES INTO SIGNIFICANT ALONG TRACK SPREADING AS MODELS ATTEMPT TO HANDLE ETT. BY TAU 72, TWO CLEAR GROUPS IMMERGE, THE FIRST LARGELY TERMINATE NEAR TOKYO (NVGM, ECMWF AND GFS). THE SECOND GROUP CONTINUES THE SYSTEM INTO THE PACIFIC ALONG WITH THE JTWC FORECAST TRACK (AFUM, UKMET AND COAMPS-TC). THE SOLID NEAR TERM AGREEMENT IS OVERSHADOWED BY THE ALONG TRACK SPREADING AFTER TAU 36, AND THE JTWC TRACK FORECAST IS THEREFOR PLACED WITH LOW CONFIDENCE. ON THE BRIGHT SIDE, RELIABLE MODEL INTENSITY GUIDANCE IS IN FAIR AGREEMENT WITH ALL MEMBERS WEAKENING THE SYSTEM THROUGH THE FORECAST PERIOD, THOUGH THE RATE OF DECLINE IS SOMEWHAT SPREAD. THE JTWC INTENSITY FORECAST IS PLACED SLIGHTLY ABOVE THE MULTI-MODEL CONSENSUS TO COMPENSATE FOR COAMPS-TC (BOTH VERSIONS) AND AHNI WHICH PLUMMET THE SYSTEMS INTENSITY UNREALISTICALLY. FOR THIS REASON THE JTWC INTENSITY FORECAST IS PLACED WITH MEDIUM CONFIDENCE. FORECAST CONFIDENCE: TRACK 0 - 72 HR: LOW TRACK 72-120 HR: LOW INTENSITY 0 - 72 HR: MEDIUM INTENSITY 72-120 HR: MEDIUM// NNNN