MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI// SUBJ/PROGNOSTIC REASONING FOR TROPICAL STORM 08W (WIPHA) WARNING NR 05// RMKS// 1. FOR METEOROLOGISTS. 2. 6 HOUR SUMMARY AND ANALYSIS. TROPICAL STORM (TS) 08W (WIPHA), LOCATED APPROXIMATELY 313 NM EAST OF HANOI, VIETNAM, HAS TRACKED NORTHWESTWARD AT 05 KNOTS OVER THE PAST SIX HOURS. ANIMATED ENHANCED INFRARED IMAGERY SHOWS A LARGE AREA OF FRAGMENTED AND POORLY ORGANIZED DEEP CONVECTION WITH MONSOON DEPRESSION CHARACTERISTICS. THE MAIN BANDS ARE FEEDING IN FROM THE SOUTH INTO A BROAD, ELONGATED AND ASYMMETRICAL LOW LEVEL CIRCULATION (LLC). THE INITIAL POSITION AND INTENSITY ARE EXTRAPOLATED FROM A 311415Z DIRECT ASCAT PASS SHOWING MULTIPLE 35-KNOT WIND BARBS ALONG THE NORTHWEST PERIPHERY OF THE LLC. THE INTENSITY IS HELD SLIGHTLY HIGHER THAN RJTD AND PGTW DVORAK ESTIMATES BUT CONSISTENT WITH THE 311800Z T2.5/35KTS FIX FROM RCTP. UPPER LEVEL ANALYSIS INDICATES AN EASTWARD OUTFLOW CHANNEL TOWARD A TUTT CELL ANCHORED OVER OKINAWA THAT IS PROVIDING VENTILATION TO THE FLARING CONVECTION. HOWEVER, THIS IS OFFSET BY A MODERATE (15-20 KNOT) EASTERLY VERTICAL WIND SHEAR (VWS). TS 08W IS TRACKING ALONG THE SOUTHWESTERN PERIPHERY OF A SUBTROPICAL RIDGE (STR). 3. FORECAST REASONING. A. THERE IS NO CHANGE TO THE FORECAST PHILOSOPHY SINCE THE PREVIOUS PROGNOSTIC REASONING MESSAGE. B. TS WIPHA IS EXPECTED TO REMAIN ON ITS CURRENT TRACK THROUGHOUT THE FORECAST, MAKING LANDFALL OVER THE LEIZHOU PENINSULA SHORTLY AFTER TAU 12. AFTERWARD, IT WILL CROSS THE GULF OF TONKIN MOMENTARILY BEFORE MAKING A FINAL LANDFALL IN SOUTH CHINA NEAR BEIHAI. LAND INTERACTION, IN ADDITION TO THE MODERATE VWS, WILL RAPIDLY ERODE THE SYSTEM, LEADING TO DISSIPATION BY TAU 36. THERE IS A SMALL PROBABILITY THAT TS 08W WILL TRACK MORE WESTWARD RESULTING IN A LONGER DRIFT OVER THE GULF OF TONKIN, HENCE, A LONGER LIFESPAN. AVAILABLE NUMERICAL MODELS ARE IN GOOD AGREEMENT WITH SOME SPREADING AFTER TAU 24, LENDING FAIR CONFIDENCE IN THE JTWC TRACK FORECAST. // NNNN NNNN