MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI// SUBJ/PROGNOSTIC REASONING FOR TROPICAL STORM 08W (WIPHA) WARNING NR 13// RMKS/ 1. FOR METEOROLOGISTS. 2. 6 HOUR SUMMARY AND ANALYSIS. TROPICAL STORM (TS) 08W (WIPHA), LOCATED APPROXIMATELY 105 NM EAST-NORTHEAST OF HANOI, VIETNAM, HAS TRACKED WESTWARD AT 08 KNOTS (KTS) OVER THE PAST SIX HOURS. ANIMATED ENHANCED INFRARED (EIR) SATELLITE IMAGERY DEPICTS CONVECTIVE BANDING WRAPPING INTO A POORLY- DEFINED LOW-LEVEL CIRCULATION CENTER. THE INITIAL POSITION WAS PLACED WITH FAIR CONFIDENCE USING A COMBINATION OF EIR, A 021746Z GMI 89 GHZ MICROWAVE IMAGE, AND ANIMATED RADAR IMAGERY. THE INITIAL 35 KT INTENSITY IS CONSISTENT WITH A RJTD SUBJECTIVE DVORAK INTENSITY ESTIMATE OF T2.5 (35 KTS). THE ENVIRONMENT, WITH MODERATE VERTICAL WIND SHEAR AND FAIR OUTFLOW, IS MARGINALLY FAVORABLE. THAT SAID, WITH THE CENTER POSITIONED OVER LAND, INTENSIFICATION IS UNLIKELY. TS 08W IS TRACKING ALONG THE SOUTHERN PERIPHERY OF A SUBTROPICAL RIDGE (STR). SOME BUILDING OF THE STR HAS ALLOWED THE ALONG-TRACK SPEED TO INCREASE OVER THE PAST SIX HOURS. 3. FORECAST REASONING. A. THERE HAS BEEN NO SIGNIFICANT CHANGE TO THE FORECAST PHILOSOPHY SINCE THE PREVIOUS PROGNOSTIC REASONING MESSAGE. B. FOR THE DURATION OF THE FORECAST, TS 08W IS EXPECTED TO TRACK WEST-SOUTHWESTWARD ALONG THE COAST OF CHINA AND VIETNAM. AROUND TAU 12, THE WEST-SOUTHWESTWARD TRACK WILL CARRY 08W INLAND, JUST SOUTH OF HANOI AND DISSIPATION IS EXPECTED BY TAU 24. DYNAMIC MODEL GUIDANCE IS IN FAIR AGREEMENT WITH THE FORECAST TRACK BUT SOME MEMBERS SHOW A TRACK SLIGHTLY SOUTH OF THE OFFICIAL FORECAST. IF THAT WERE TO OCCUR, THE INTENSITY AND DURATION OF THE FORECAST COULD CHANGE. OVERALL, THERE IS FAIR CONFIDENCE IN THE JTWC FORECAST TRACK.// NNNN NNNN