MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI// SUBJ/PROGNOSTIC REASONING FOR TYPHOON 17W (ATSANI) WARNING NR 15// RMKS// 1. FOR METEOROLOGISTS. 2. 6 HOUR SUMMARY AND ANALYSIS. TYPHOON(TY) 17W (ATSANI), LOCATED APPROXIMATELY 717 NM EAST OF ANDERSEN AFB, GUAM HAS TRACKED NORTHWESTWARD AT 11 KNOTS OVER THE PAST SIX HOURS. ANIMATED ENHANCED INFRARED SATELLITE DEPICTS DEEPENED CONVECTION WITH TIGHTLY-CURVED BANDS WRAPPING INTO A WELL- DEFINED 8 NM DIAMETER EYE THAT SUPPORTS THE HIGH CONFIDENCE IN THE CURRENT POSITION. THE INITIAL INTENSITY OF 105 KNOTS IS BASED ON CORRESPONDING DVORAK INTENSITY ESTIMATES FROM ALL REPORTING AGENCIES. UPPER-LEVEL ANALYSIS INDICATES FAVORABLE ENVIRONMENT WITH LOW VWS AND RADIAL OUTFLOW SUPPORTED BY AN ANALYZED POINT-SOURCE. NEAR RADIAL OUTFLOW AND LOW VWS. TY 17W IS TRACKING ALONG THE SOUTHWESTERN PERIPHERY OF A STR TO THE NORTHEAST. 3. FORECAST REASONING. A. NO CHANGE TO THE FORECAST PHILOSOPHY SINCE THE PREVIOUS PROGNOSTIC REASONING MESSAGE. HOWEVER, THE SYSTEM IS EXPECTED TO REACH PEAK INTENSITY SOONER. B. TY 17W WILL REMAIN ON A NORTHWESTWARD TRAJECTORY THROUGH TAU 72 UNDER THE STEERING STR. VERY FAVORABLE ENVIRONMENTAL AND UPPER- LEVEL CONDITIONS ARE EXPECTED TO PERSIST ALLOWING THE SYSTEM TO FURTHER INTENSIFY LEADING TO A PEAK INTENSITY OF 140 BY TAU 36. AFTER TAU 48, INCREASING VWS WILL BEGIN TO WEAKEN THE SYSTEM. C. IN THE EXTENDED TAUS, TY 17W CONTINUES TO TRACK NORTHWESTWARD UNDER THE STEERING STR. THE COMBINED EFFECTS OF LOWER OHC VALUES AND INCREASED VWS WILL CONTINUE TO DECAY TY ATSANI. AVAILABLE MODEL GUIDANCE REMAINS IN TIGHT AGREEMENT LENDING HIGH CONFIDENCE IN THE JTWC FORECAST TRACK.// NNNN NNNN