MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI// SUBJ/PROGNOSTIC REASONING FOR TYPHOON 09W (RAMMASUN) WARNING NR 30// RMKS/ 1. FOR METEOROLOGISTS. 2. 6 HOUR SUMMARY AND ANALYSIS. TYPHOON 09W (RAMMASUN), LOCATED APPROXIMATELY 232 NM SOUTH OF HONG KONG, HAS TRACKED NORTHWESTWARD AT 13 KNOTS OVER THE PAST SIX HOURS. ANIMATED ENHANCED INFRARED SATELLITE IMAGERY (EIR) SHOWS TY 09W CONTINUES TO INTENSIFY IN A FAVORABLE ENVIRONMENT WITH HIGH SEA SURFACE TEMPERATURES (30 TO 31 DEGREES CELSIUS) AND STEADY IMPROVE- MENTS IN THE EYEWALL STRUCTURE. THE CURRENT INTENSITY OF 120 KNOTS IS BASED ON DVORAK ESTIMATES RANGING FROM 115 TO 127 KNOTS. UPPER LEVEL ANALYSIS SHOWS A FAVORABLE ENVIRONMENT CHARACTERIZED BY VIGOROUS EQUATORWARD OUTFLOW AND LOW (05 TO 10 KNOTS) VERTICAL WIND SHEAR. THE INITIAL POSITION IS BASED UPON THE DEFINED EYE FEATURE IN THE EIR LOOP WITH HIGH CONFIDENCE. TY 09W IS STEADILY TRACKING WEST-NORTHWEST ALONG THE SOUTHWESTERN PERIPHERY OF THE SUBTROPICAL RIDGE (STR) NORTHEAST OF THE SYSTEM. 3. FORECAST REASONING. A. NO CHANGE TO FORECAST PHILOSOPHY SINCE THE PREVIOUS PROGNOSTIC REASONING MESSAGE. B. TY 09W IS FORECAST TO REMAIN ON A GENERALLY WEST-NORTHWESTWARD TRACK THROUGH THE REMAINDER OF THE FORECAST AS THE STR PERSISTS TO THE NORTHWEST OF THE SYSTEM. TY 09W IS EXPECTED TO STRENGTHEN FOR THE NEXT 12 HOURS BEFORE THE FRICTIONAL EFFECTS OF HAINAN ISLAND BEGIN TO WEAKEN THE SYSTEM BY TAU 24. WEAKENING WILL PERSIST AFTER TRACKING OVER THE NORTHERN HALF OF HAINAN ISLAND AND AS THE SYSTEM BEGINS TO INTERACT WITH THE LUICHOW PENINSULA. ONCE TY 09W MAKES LANDFALL IN THE BORDER REGION OF NORTHERN VIETNAM AND SOUTHERN CHINA, A RAPID WEAKENING WITH COMPLETE DISSIPATION OF THE TROPICAL SYSTEM IS EXPECTED BY TAU 72. NUMERIC MODEL GUIDANCE IS IN VERY TIGHT AGREEMENT WITH THE TRACK FORECAST, WHICH IS POSITIONED WITH HIGH CONFIDENCE, CLOSE TO THE MULTI-MODEL CONSENSUS.// NNNN NNNN