MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI// SUBJ/PROGNOSTIC REASONING FOR TYPHOON 09W (CHAN-HOM) WARNING NR 35// RMKS/ 1. FOR METEOROLOGISTS. 2. 6 HOUR SUMMARY AND ANALYSIS. TYPHOON (TY) 09W (CHAN-HOM), LOCATED APPROXIMATELY 261 NM SOUTH- SOUTHEAST OF KADENA AB, HAS TRACKED NORTHWESTWARD AT 12 KNOTS OVER THE PAST SIX HOURS. ANIMATED MSI DEPICTS THINNING DEEP CONVECTION WITH A 28 NM DIAMETER EYE. THE CURRENT POSITION IS BASED ON THE EYE FEATURE WITH HIGH CONFIDENCE. THE INITIAL INTENSITY REMAINS AT 90 KNOTS BASED ON DVORAK CURRENT INTENSITY ESTIMATES FROM PGTW. UPPER-LEVEL ANALYSIS INDICATES TY 09W IS LOCATED IN AN AREA OF LOW TO MODERATE (10 TO 20) VWS BEING OFFSET BY THE EXCELLENT EQUATORWARD OUTFLOW AS EVIDENT ON THE WATER VAPOR IMAGERY. THE CYCLONE IS TRACKING ALONG THE SOUTHWESTERN PERIPHERY OF AN EXTENSION OF THE STR TO THE NORTH. 3. FORECAST REASONING. A. NO CHANGE TO THE FORECAST PHILOSOPHY SINCE THE PREVIOUS PROGNOSTIC REASONING MESSAGE. B. TY 09W IS FORECAST TO CONTINUE TRACKING NORTHWESTWARD UNDER THE STEERING INFLUENCE OF THE STR THROUGH TAU 72. FAVORABLE CONDITIONS WILL PERSIST, ALLOWING TY CHAN-HOM TO STEADILY INTENSIFY LEADING TO A PEAK INTENSITY OF 115 KNOTS BY TAU 36. AFTERWARD, TY CHAN-HOM IS EXPECTED TO BEGIN ITS WEAKENING TREND AS THE SYSTEM INTERACTS WITH THE EASTERN COAST OF CHINA. DYNAMIC GUIDANCE IS IN TIGHT AGREEMENT THROUGH THIS PERIOD, LENDING HIGH CONFIDENCE TO THIS PORTION OF THE TRACK FORECAST. C. IN THE EXTENDED TAUS, AN APPROACHING MID-LATITUDE TROUGH WILL PASS TO THE NORTH, CAUSING A BREAK IN THE STR AND ALLOWING TY 09W TO TURN NORTHEASTWARD. UNFAVORABLE ENVIRONMENTAL CONDITIONS ALONG WITH LAND INTERACTION WILL FURTHER DECAY THE SYSTEM. NUMERICAL MODEL GUIDANCE SHOWS A LARGE SPREAD AND SIGNIFICANT DIFFERENCES IN THE TRACK SPEEDS; THEREFORE, DUE TO SOME UNCERTAINTY IN TIMING AND SPEED OF THE SYSTEM IN THE EXTENDED FORECAST TRACK, THE JTWC TRACK FORECAST CONFIDENCE LEVEL REMAINS LOW.// NNNN NNNN