MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI// SUBJ/PROGNOSTIC REASONING FOR TYPHOON 21W (DUJUAN) WARNING NR 21// RMKS/ 1. FOR METEOROLOGISTS. 2. 6 HOUR SUMMARY AND ANALYSIS. TYPHOON (TY) 21W (DUJUAN), LOCATED APPROXIMATELY 282 NM SOUTH- SOUTHEAST OF KADENA AB, JAPAN HAS TRACKED NORTHWESTWARD AT 09 KNOTS OVER THE PAST SIX HOURS. ANIMATED ENHANCED INFRARED SATELLITE IMAGERY SHOWS AN IMPROVING CONVECTIVE CORE STRUCTURE WITH COOLER CLOUD TOPS SURROUNDING A LARGE 33NM EYE WHICH SUPPORTS THE INITIAL POSITION WITH HIGH CONFIDENCE. THE WATER VAPOR LOOP SHOWS A MORE SYMMETRIC CORE STRUCTURE WITH DECREASED DRY AIR IMPACTING THE TYPHOON. HOWEVER, SOME SUBSIDENCE FROM THE STR TO THE NORTHWEST IS CAUSING SOME PRESSURE ON THE WESTERN FRONT. A 261750Z AMSU-B MICROWAVE IMAGE SHOWS A NEARLY CLOSED OFF MICROWAVE EYE FEATURE SURROUNDED BY AN INTENSE CONVECTIVE CORE. THE CURRENT INTENSITY HAS BEEN INCREASED TO 105 KNOTS BASED ON AN ASSESSMENT OF DVORAK INTENSITY ESTIMATES FROM ALL AGENCIES. ENVIRONMENTAL ANALYSIS INDICATES AN IMPROVED ENVIRONMENT WITH NEAR RADIAL OUTFLOW AND LOW VWS. TY DUJUAN IS TRACKING ALONG THE SOUTHWESTERN PERIPHERY OF A DEEP LAYERED STR. 3. FORECAST REASONING. A. NO CHANGE IN THE FORECAST PHILOSOPHY SINCE THE PREVIOUS PROGNOSTIC REASONING MESSAGE. B. TY DUJUAN WILL MAINTAIN A NORTHWESTWARD TRAJECTORY THROUGHOUT THE FORECAST PERIOD AS THE STEERING STR CONTINUES TO BUILD OVER THE SYSTEM. CURRENT ENVIRONMENTAL CONDITIONS WILL SUPPORT INTENSIFICATION OVER THE NEXT 24 HOURS WITH A PEAK OF 120 KNOTS. BEYOND TAU 24, TY 21W WILL BEGIN TO WEAKEN DUE TO LOWER OHC VALUES, AN INCREASE IN VWS AND LAND INTERACTION WITH THE MOUNTAINOUS TERRAIN OF TAIWAN. DUE TO THE HIGH LIKELIHOOD OF A LEEWARD JUMP SCENARIO AS THE TYPHOON PASSES THROUGH TAIWAN, THERE IS LIMITED CONFIDENCE IN THE TAU 48 POSITION. BY TAU 72, EXPECT SIGNIFICANT DEGRADATION OF THE SYSTEM AS IT PROPAGATES THROUGH SOUTHEAST CHINA. C. EXPECT COMPLETE DISSIPATION OF THE SYSTEM BY TAU 96 IN SOUTH CENTRAL CHINA. DYNAMIC MODEL GUIDANCE IS IN GOOD AGREEMENT THROUGHOUT THE FORECAST PERIOD LEADING TO HIGH CONFIDENCE IN THE JTWC FORECAST TRACK.// NNNN NNNN