WDPN31 PGTW 280300 MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI// SUBJ/PROGNOSTIC REASONING FOR TYPHOON 21W (DUJUAN) WARNING NR 26// RMKS/ 1. FOR METEOROLOGISTS. 2. 6 HOUR SUMMARY AND ANALYSIS. TYPHOON (TY) 21W (DUJUAN LOCATED APPROXIMATELY 162 NM SOUTHEAST OF TAIPEI, TAIWAN, HAS TRACKED WEST-NORTHWESTWARD AT 11 KNOTS OVER THE PAST SIX HOURS. ANIMATED MSI CONTINUES TO SHOW THE SYSTEM HAS MAINTAINED SYMMETRIC DEEP CONVECTION WRAPPING TIGHTLY INTO A LARGE 46-NM EYE, ALLOWING FOR THE CURRENT POSITION TO BE LAID WITH HIGH CONFIDENCE. THE INITIAL INTENSITY IS BASED ON DVORAK INTENSITY ESTIMATES FROM ALL REPORTING AGENCIES AT 127 KNOTS AND SATCON INTENSITY OF 126 KNOTS. UPPER LEVEL ANALYSIS INDICATES THE SYSTEM REMAINS IN A LOW (05-10 KNOT) VWS AREA WITH NEAR RADIAL OUTFLOW. THE CYCLONE IS CURRENTLY TRACKING ALONG THE SOUTHERN PERIPHERY OF AN EXTENSION OF THE STR TO THE EAST. 3. FORECAST REASONING. A. NO SIGNIFICANT CHANGE IN THE FORECAST PHILOSOPHY SINCE THE PREVIOUS PROGNOSTIC REASONING MESSAGE. B. TY DUJUAN WILL MAINTAIN A WEST-NORTHWESTWARD TRAJECTORY THROUGH THE END OF THE FORECAST PERIOD UNDER THE STEERING INFLUENCE OF THE STR AS THE EXTENSION SLOWLY RETREATS TO THE EAST AND THE RIDGE SLOWLY TRACKS TO THE WEST. EXPECT TY 21W TO BEGIN TO DECREASE IN INTENSITY AS IT IMPACTS EASTERN TAIWAN IN TAU 12 AND TRACKS OVER THE CENTRAL MOUNTAINS RE-EMERGING IN THE COOL WATERS OF THE TAIWAN STRAIT. BEYOND TAU 24, TY 21W WILL MAKE LANDFALL IN CHINA AND CONTINUE TO DECAY AS FRICTIONAL FORCES WILL CAUSE THE SYSTEM TO COMPLETELY DISSIPATE BY TAU 48. ADDITIONALLY, AN APPROACHING MID- LATITUDE TROUGH WILL FORCE THE SYSTEM TO TURN MORE POLEWARD AT THE END OF THE FORECAST PERIOD. DYNAMIC MODEL GUIDANCE IS IN GOOD AGREEMENT THROUGHOUT THE FORECAST PERIOD LEADING TO HIGH CONFIDENCE IN THE JTWC FORECAST WHICH IS IN LINE WITH MULTI-MODEL GUIDANCE.// NNNN