WDXS31 PGTW 291500 MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI// SUBJ/PROGNOSTIC REASONING FOR TROPICAL CYCLONE 08S (CHENESO) WARNING NR 016// RMKS/ 1. FOR METEOROLOGISTS. 2. 6 HOUR SUMMARY AND ANALYSIS. SUMMARY: INITIAL POSITION: 29.9S 47.6E INITIAL INTENSITY: 50 KTS GEOGRAPHIC REFERENCE: 610 NM SOUTHEAST OF EUROPA ISLAND MOVEMENT PAST 6 HOURS: EAST-SOUTHEASTWARD AT 24 KTS SIGNIFICANT WAVE HEIGHT: 24 FEET SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION: ANIMATED MULTISPECTRAL SATELLITE IMAGERY (MSI) DEPICTS AN EXPOSED, WELL-DEFINED LOW-LEVEL CIRCULATION WITH RAPIDLY-ERODING DEEP CONVECTION SHEARED TO THE SOUTHEAST. THE INITIAL POSITION IS PLACED WITH HIGH CONFIDENCE BASED ON THE MSI. A 291307Z SSMIS 91GHZ MICROWAVE IMAGE REVEALS SHALLOW BANDING WRAPPING INTO THE LOW-LEVEL CIRCULATION CENTER WITH THE BULK OF THE DEEP CONVECTION DISPLACED OVER THE SOUTHERN SEMICIRCLE. ADDITIONALLY, THERE IS EXTENSIVE DRY AIR PRESENT OVER THE WESTERN SEMICIRCLE. THE INITIAL INTENSITY OF 50 KTS IS ASSESSED WITH MEDIUM CONFIDENCE BASED ON A 290601Z METOP-B ASCAT PARTIAL IMAGE, WHICH SHOWS 40-45 KNOT WINDS ALONG THE WESTERN PERIPHERY, AND RECENT SMAP DATA. DUE TO THE LACK OF DEEP CONVECTION, DVORAK SUBJECTIVE ESTIMATES AND ADT OBJECTIVE ESTIMATES ARE UNREALISTICALLY LOW AND ARE NOT INCORPORATED INTO THE INITIAL INTENSITY ASSESSMENT. INITIAL WIND RADII BASIS: OBJECTIVE BEST TRACK CURRENT STEERING MECHANISM: DEEP-LAYERED SUBTROPICAL RIDGE (STR) POSITIONED TO THE NORTHEAST AGENCY DVORAK AND AUTOMATED FIXES: PGTW: T2.0 - 30 KTS DEMS: T2.5 - 35 KTS CIMSS SATCON: 66 KTS AT 290723Z CIMSS ADT: 34 KTS AT 291200Z FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: MARGINALLY UNFAVORABLE VWS: 20-25 KTS SST: 24-25 CELSIUS OUTFLOW: STRONG POLEWARD OTHER FACTORS: DRY AIR ENTRAINMENT ANALYSIS CONFIDENCE: INITIAL POSITION: MEDIUM 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: TROPICAL CYCLONE (TC) 08S HAS COMMENCED EXTRA-TROPICAL TRANSITION (ETT) AND IS BEGINNING TO INTERACT WITH A STRONG BAROCLINIC ZONE. TC 08S WILL ACCELERATE SOUTHEASTWARD OVER THE NEXT DAY AND IS EXPECTED TO RAPIDLY COMPLETE ETT, GAINING FRONTAL CHARACTERISTICS AS IT TRACKS UNDER THE JET NEAR TAU 24. MODEL DISCUSSION: NUMERICAL MODEL GUIDANCE REMAINS IN TIGHT AGREEMENT WITH A 73NM SPREAD IN SOLUTIONS AT TAU 24, THEREFORE, THERE IS HIGH CONFIDENCE IN THE JTWC FORECAST TRACK. RELIABLE INTENSITY GUIDANCE SUPPORTS THE JTWC INTENSITY FORECAST WITH MEDIUM CONFIDENCE. TC 08S IS EXPECTED TO MAINTAIN GALE-FORCE TO STORM-FORCE WINDS AFTER TRANSITIONING TO A COLD-CORE EXTRA-TROPICAL LOW WHILE TRACKING SOUTHEASTWARD. FORECAST CONFIDENCE: TRACK 0 - 72 HR: HIGH INTENSITY 0 - 72 HR: MEDIUM// NNNN