WDPN31 PGTW 232100 MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI// SUBJ/PROGNOSTIC REASONING FOR TROPICAL DEPRESSION 17W (TALAS) WARNING NR 009// RMKS/ 1. FOR METEOROLOGISTS. 2. 6 HOUR SUMMARY AND ANALYSIS. SUMMARY: INITIAL POSITION: 32.9N 137.2E INITIAL INTENSITY: 25 KTS GEOGRAPHIC REFERENCE: 190 NM SOUTHWEST OF YOKOSUKA, JAPAN MOVEMENT PAST 6 HOURS: EAST-NORTHEASTWARD AT 09 KTS SIGNIFICANT WAVE HEIGHT: 14 FEET SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION: ANIMATED ENHANCED INFRARED (EIR) SATELLITE IMAGERY DEPICTS A RAPIDLY-WEAKENING, RAGGED LOW-LEVEL CIRCULATION (LLC) EMBEDDED IN THE FRONTAL BOUNDARY WITH DEEP CONVECTION SHEARED 140NM NORTH-NORTHEAST. ANIMATED RADAR IMAGERY SHOWS A FRONTAL BAND EXTENDING FROM HONSHU SOUTHWARD WITH NO DEFINED LLC DUE TO THE SHALLOW, WEAK NATURE OF THE SYSTEM. THE INITIAL POSITION IS PLACED WITH HIGH CONFIDENCE BASED ON THE EIR IMAGERY. THE INITIAL INTENSITY OF 25 KTS IS ASSESSED WITH HIGH CONFIDENCE BASED ON THE DVORAK DATA-T ESTIMATES AND CIMSS ADT ESTIMATE. TD 17W IS LOCATED WITHIN AN UNFAVORABLE ENVIRONMENT UNDER THE UPPER-LEVEL WESTERLIES WITH MODERATE TO STRONG VERTICAL WIND SHEAR, AND IS INTERACTING WITH THE BAROCLINIC ZONE. INITIAL WIND RADII BASIS: NOT APPLICABLE (THERE ARE NO INITIAL WIND RADII). CURRENT STEERING MECHANISM: NORTHWESTERN PERIPHERY OF THE LOW- TO MID-LEVEL SUBTROPICAL RIDGE (STR) AGENCY DVORAK AND AUTOMATED FIXES: PGTW: T1.5 - 25 KTS RJTD: T1.5 - 25 KTS CIMSS SATCON: 35 KTS AT 231714Z CIMSS ADT: 25 KTS AT 231750Z FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: UNFAVORABLE VWS: 20-25 KTS SST: 27-28 CELSIUS OUTFLOW: MODERATE POLEWARD OTHER FACTORS: BAROCLINIC INTERACTION AND DRY AIR ENTRAINMENT ANALYSIS CONFIDENCE: INITIAL POSITION: HIGH INITIAL INTENSITY: HIGH INITIAL WIND RADII: NOT APPLICABLE 3. FORECAST REASONING. SIGNIFICANT FORECAST CHANGES: THERE ARE NO SIGNIFICANT CHANGES TO THE FORECAST FROM THE PREVIOUS WARNING. FORECAST DISCUSSION: TD 17W WILL CONTINUE TRACKING EAST-NORTHEASTWARD ALONG THE NORTHWESTERN PERIPHERY OF THE LOW-LEVEL STR THROUGH THE FORECAST PERIOD. THE SYSTEM IS RAPIDLY WEAKENING AND IS FORECAST TO DISSIPATE WITHIN THE NEXT 06-24 HOURS AS IT BECOMES ABSORBED IN THE FRONTAL BOUNDARY. THE NEXT WARNING AT 240000Z WILL LIKELY BE THE FINAL WARNING ON THIS SYSTEM. MODEL DISCUSSION: NUMERICAL MODEL GUIDANCE IS IN FAIR AGREEMENT AND GENERALLY SUPPORTS THE JTWC FORECAST TRACK SOUTH OF HONSHU WITH MEDIUM CONFIDENCE. THE BULK OF THE INTENSITY GUIDANCE INDICATES STEADY WEAKENING WITH THE EXCEPTION OF HWRF, WHICH SHOWS AN INCREASE TO 33 KNOTS AT TAU 12 THEN STEADY WEAKENING. THIS INTENSIFICATION IS ASSOCIATED WITH A SURGE OF STRONGER NORTHERLY WINDS OVER THE NORTHWEST QUADRANT ASSOCIATED WITH THE BAROCLINIC ZONE. FORECAST CONFIDENCE: TRACK 0 - 72 HR: MEDIUM INTENSITY 0 - 72 HR: MEDIUM// NNNN