WDPN31 PGTW 270300 MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI// SUBJ/PROGNOSTIC REASONING FOR TROPICAL STORM 05W (MIRINAE) WARNING NR 07// RMKS// 1. FOR METEOROLOGISTS. 2. 6 HOUR SUMMARY AND ANALYSIS. TROPICAL STORM 05W (MIRINAE), LOCATED APPROXIMATELY 176 NM EAST- SOUTHEAST OF HANOI, VIETNAM, HAS TRACKED WEST-NORTHWESTWARD AT 12 KNOTS OVER THE PAST SIX HOURS. THE CURRENT POSITION IS BASED ON RECENT SATELLITE FIXES FROM RJTD AND PGTW. THE INTENSITY OF 35 KNOTS IS CONSISTENT WITH SUBJECTIVE T-NUMBER ESTIMATES FROM THE SAME REPORTING AGENCIES. TS 05W HAS EMERGED OVER THE GULF OF TONKIN DURING THE PAST SIX HOURS AFTER CROSSING HAINAN ISLAND. THE SYSTEM CONTINUES TO TRACK WEST-NORTHWESTWARD ALONG THE PERIPHERY OF A SUBTROPICAL STEERING RIDGE TO THE NORTH. PERSISTENT NORTHEASTERLY VERTICAL WIND SHEAR HAS LEFT THE LOW-LEVEL CIRCULATION CENTER PARTIALLY EXPOSED. 3. FORECAST REASONING. A. THE FORECAST PHILOSOPHY HAS NOT CHANGED SINCE THE PREVIOUS FORECAST. B. TS 05W IS EXPECTED TO TRACK WEST-NORTHWESTWARD THROUGH THE FORECAST PERIOD UNDER THE CONTINUED INFLUENCE OF THE CURRENT STEERING RIDGE. SLIGHT INTENSIFICATION IS POSSIBLE WITHIN THE NEXT 12 HOURS AS SUSTAINED VERTICAL WINDS SHEAR COUNTERACTS THE FAVORABLE ENVIRONMENTAL INFLUENCES OF PASSAGE OVER VERY WARM WATER AND STRONG EQUATORWARD DIFFLUENCE ALOFT. TS 05W IS EXPECTED TO TRACK INTO NORTHERN VIETNAM AFTER TAU 12 AND STEADILY DISSIPATE THEREAFTER. NUMERICAL MODEL TRACK FORECAST GUIDANCE IS SPLIT, WITH THE GFS, GEFS, AND GFS-INITIALIZED MESOSCALE MODELS INDICATING A MORE POLEWARD TRACK TOWARD A DEVELOPING BREAK IN THE STEERING RIDGE, AND OTHER MODELS INCLUDING NAVGEM, ECMWF, JGSM, AND TC-EPS DEPICTING A STEADY WEST-NORTHWESTWARD TRACK FOR THE NEXT 36 HOURS. THE CURRENT FORECAST IS CONSISTENT WITH THE SECOND MODEL GROUPING, WHICH HAS DEMONSTRATED A BETTER REPRESENTATION OF THE STEERING PATTERN OVER THE PAST DAY OR SO. GIVEN GOOD AGREEMENT WITHIN THE WEST- NORTHWESTWARD MODEL GROUPING AND RECENT TRACK TRENDS, THERE IS HIGH CONFIDENCE IN THE CURRENT TRACK FORECAST, WHICH LIES TO THE LEFT OF THE MULTI-MODEL CONSENSUS./=