MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI// SUBJ/PROGNOSTIC REASONING FOR TROPICAL STORM 09W (CHAN-HOM) WARNING NR 47// RMKS/ 1. FOR METEOROLOGISTS. 2. 6 HOUR SUMMARY AND ANALYSIS. TROPICAL STORM (TS) 09W (CHAN-HOM), LOCATED APPROXIMATELY 292 NM SOUTH-SOUTHWEST OF YONGSAN AIN, SOUTH KOREA, HAS TRACKED NORTH- NORTHEASTWARD AT 17 KNOTS OVER THE PAST SIX HOURS. ANIMATED MULTISPECTRAL SATELLITE IMAGERY (MSI) SHOWS SIGNIFICANT WEAKENING OF THE SYSTEM EVIDENCED BY SHEARING AND CONVECTIVE EROSION. THE INITIAL POSITION IS BASED ON THE MSI LOOP AND ON A MICROWAVE EYE FEATURE IN THE 112300Z F18 91V IMAGE WITH HIGH CONFIDENCE. THE INITIAL INTENSITY OF 55 KNOTS IS BASED ON AN ASSESSMENT OF ALL AGENCY DVORAK ESTIMATES AND REFLECTS THE SYSTEMS DEGRADATION. UPPER-LEVEL ANALYSIS INDICATES THE SYSTEM HAS DRIFTED FURTHER INTO THE COLD YELLOW SEA IN AN AREA OF MODERATE TO STRONG (20-30 KNOT) VWS. HOWEVER, A STRONG POLEWARD OUTFLOW IS PROVIDING VENTILATION TO THE WANING CONVECTION. AT THE SURFACE, ALONG-TRACK SSTS ARE BELOW 25 CELSIUS. THE CYCLONE IS ACCELERATING NORTHEASTWARD ON THE POLEWARD SIDE OF THE STEERING STR. 3. FORECAST REASONING. A. THERE IS NO CHANGE TO THE FORECAST PHILOSOPHY SINCE THE PREVIOUS PROGNOSTIC REASONING MESSAGE. B. TS CHANG-HOM IS EXPECTED TO CONTINUE ACCELERATING NORTHEASTWARD THROUGH THE REMAINDER OF THE FORECAST PERIOD. IT WILL MAKE LANDFALL OVER NORTH KOREA, JUST NORTH OF THE DMZ, SHORTLY AFTER TAU 12, THEN DISSIPATE OVER THE RUGGED HAMGYONG MOUNTAINS BY TAU 24. TS 09W WILL CONTINUE TO WEAKEN RAPIDLY DUE TO INCREASING VWS AND COOLING SSTS; BY THE TIME IT MAKES LANDFALL, IT WILL BE AT MINIMAL TROPICAL STORM INTENSITY. HOWEVER, THE CYCLONE PACKS A LARGE WIND RADIUS AND IS STILL EXPECTED TO USHER IN A WIDE SWATH OF GALE-FORCE WINDS TO THE WEST COAST OF KOREA. THE NUMERIC MODELS REMAIN IN TIGHT AGREEMENT, LENDING HIGH CONFIDENCE TO THE JTWC TRACK FORECAST.// NNNN NNNN