WDPN31 PGTW 161500 MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI// SUBJ/PROGNOSTIC REASONING FOR TYPHOON 14W (KAI-TAK) WARNING NR 17// RMKS// 1. FOR METEOROLOGISTS. 2. 6 HOUR SUMMARY AND ANALYSIS. TYPHOON (TY) 14W (KAI-TAK), LOCATED APPROXIMATELY 155 NM SOUTH OF HONG KONG, HAS TRACKED WEST-NORTHWESTWARD AT 14 KNOTS OVER THE PAST SIX HOURS. ANIMATED INFRARED SATELLITE IMAGERY INDICATES THAT DEEP CONVECTION HAS DECREASED IN AREAL EXTENT OVER THE PAST SIX HOURS WITH SLIGHT WEAKENING IN DEEP CONVECTIVE BANDING. DESPITE THIS DEGRADED IR SIGNATURE, A 161247Z SSMIS IMAGE CONTINUES TO INDICATE A WELL-DEFINED LOW-LEVEL CIRCULATION CENTER WITH TIGHTLY-CURVED CONVECTIVE BANDING WRAPPING INTO THE CENTER. SATELLITE IMAGERY, HOWEVER, SHOWS THAT THE BULK OF THE DEEP CONVECTION REMAINS CONFINED TO THE SOUTHERN SEMI-CIRCLE. ANIMATED WATER VAPOR IMAGERY SHOWS THAT A TUTT CELL, WHICH WAS LOCATED OVER THE NORTHERN PERIPHERY OF THE SYSTEM, HAS RAPIDLY TRACKED WEST INTO CHINA AND NORTHEASTERLY UPPER- LEVEL FLOW HAS SLACKENED LEADING TO THE IMPROVED ENVIRONMENT. THE INITIAL POSITION IS BASED ON RADAR FIXES AND THE SSMIS IMAGE WITH GOOD CONFIDENCE. THE INITIAL INTENSITY IS HELD AT 65 KNOTS BASED ON DVORAK ESTIMATES OF 65 KNOTS FROM PGTW, KNES AND RJTD. 3. FORECAST REASONING. A. NO CHANGE TO THE FORECAST PHILOSOPHY SINCE THE PREVIOUS PROGNOSTIC REASONING MESSAGE. B. TY 14W IS TRACKING ALONG THE SOUTHERN PERIPHERY OF A DEEP SUBTROPICAL RIDGE (STR) POSITIONED OVER SOUTHEAST CHINA. THE 16/00Z 500MB UPPER-AIR DATA INDICATES THAT THE STR HAS STRENGTHENED AND BROADENED OVER THE PAST 24 HOURS WITH EASTERLY FLOW ENTRENCHED ACROSS SOUTHERN CHINA, THEREFORE, MODEL GUIDANCE IS IN TIGHT AGREEMENT AND SUPPORTS A CONTINUED WESTWARD TO WEST-NORTHWESTWARD TRACK THROUGH THE FORECAST PERIOD. TY 14W IS EXPECTED TO INTENSIFY UNDER FAVORABLE CONDITIONS THROUGH TAU 12 BUT SHOULD THEN WEAKEN SIGNIFICANTLY DUE TO INCREASING INTERACTION WITH LAND. AFTER TAU 24, TY 14W WILL RAPIDLY DECAY AS IT TRACKS AWAY FROM THE GULF OF TONKIN AND OVER THE MOUNTAINOUS REGION OF NORTHERN VIETNAM. THERE IS HIGH CONFIDENCE IN THE FORECAST TRACK.// NNNN