WDPN31 PGTW 210900 MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI// SUBJ/PROGNOSTIC REASONING FOR TROPICAL STORM 01W (DUJUAN) WARNING NR 017// RMKS/ 1. FOR METEOROLOGISTS. 2. 6 HOUR SUMMARY AND ANALYSIS. TROPICAL STORM (TS) 01W (DUJUAN), LOCATED APPROXIMATELY 518 NM SOUTHEAST OF MANILA, PHILIPPINES, HAS TRACKED WEST-NORTHWESTWARD AT 17 KNOTS OVER THE PAST SIX HOURS. ANIMATED MULTISPECTRAL SATELLITE IMAGERY (MSI) SHOWS DEEP, EXPANSIVE, FLARING CONVECTION OVER SOUTHEASTERN PHILIPPINES AND AHEAD OF THE THE LOW LEVEL CIRCULATION (LLC). INITIAL POSITION IS PLACED WITH FAIR CONFIDENCE BASED ON LOW CLOUD TRACING INTO THE LLC IN THE MSI LOOP AND LINED UP WITH A RAGGED LLC FEATURE IN THE 210425Z AMSR2 MICROWAVE IMAGE. THE INITIAL INTENSITY OF 35KTS IS BASED ON AN OVERALL ASSESSMENT OF AGENCY DVORAK ESTIMATES OF T1.0/25KTS (KNES), T2.0/30KTS (RJTD), T2.5/35KTS (PGTW), AND OBJECTIVE ADT OF T3.2/47KTS, AND REFLECTS THE 6-HR CONVECTIVE IMPROVEMENT. ANALYSIS INDICATES WARM (29C) ALONG-TRACK SST IN THE PHILIPPINE SEA AND ROBUST WEST AND POLEWARD OUTFLOW ALOFT. A SLIGHT DECREASE IN VWS DUE TO THE STORM MOTION MOVING MORE IN-PHASE WITH THE MID AND UPPER LEVEL WIND FLOW HAS ENHANCED THE CONVECTION AHEAD OF THE LLC. ADDITIONALLY, THE WARM MOIST AIR AHEAD OF THE TS IS CONTINUALLY OVERRUNNING THE COLDER NORTHEASTERLY WIND IN THE PHILIPPINE SEA INCREASING THE INSTABILITY. THE CYCLONE IS TRACKING UNDER THE STEERING INFLUENCE OF THE SUBTROPICAL RIDGE (STR) TO THE NORTHEAST. 3. FORECAST REASONING. A. THERE IS NO SIGNIFICANT CHANGE IN THE FORECAST PHILOSOPHY FROM THE PREVIOUS PROGNOSTIC REASONING MESSAGE. B. TS DUJUAN WILL CONTINUE TRACKING NORTHWESTWARD UNDER THE STR, MAKING INITIAL LANDFALL OVER LEYTE, PHILIPPINES, AFTER TAU 12 AND THEN CROSS THE VISAYAN ISLANDS, CLIPPING THE SOUTHERN TIP OF MINDORO, BEFORE EXITING INTO THE SOUTH CHINA SEA. THE SYSTEM WILL MAINTAIN ITS CURRENT INTENSITY UP TO TAU 12; AFTERWARD, INCREASED RELATIVE VWS (25KTS+) COMBINED WITH THE RUGGED TERRAIN OF THE ISLANDS WILL ERODE THE TS TO DISSIPATION BY TAU 48, POSSIBLY SOONER. NUMERICAL MODELS DIVERGE AND BIFURCATE TO 320NM+ BY TAU 48 WITH NAVGEM, UKMET, AND JGSM OFFERING A MORE POLEWARD SOLUTION AND THE REMAINDER OF THE MODEL ENVELOPE, INCLUDING ECMWF AND GFS, OFFERING A MORE EQUATORWARD TRACK . THIS INDICATES UNCERTAINTY IN THE MODELS TRACKING A WEAK VORTEX, LENDING OVERALL LOW CONFIDENCE IN THE JTWC TRACK FORECAST BEYOND TAU 24.// NNNN