WDPN31 PGTW 211500 MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI// SUBJ/PROGNOSTIC REASONING FOR TROPICAL STORM 01W (DUJUAN) WARNING NR 018// RMKS/ 1. FOR METEOROLOGISTS. 2. 6 HOUR SUMMARY AND ANALYSIS. TROPICAL STORM (TS) 01W (DUJUAN), LOCATED APPROXIMATELY 382 NM SOUTHEAST OF MANILA, PHILIPPINES, HAS TRACKED WEST-NORTHWESTWARD AT 23 KNOTS OVER THE PAST SIX HOURS. ANIMATED ENHANCED INFRARED (EIR) SATELLITE IMAGERY (MSI) SHOWS THE DEEP, EXPANSIVE, FLARING CONVECTION AHEAD OF THE THE LOW LEVEL CIRCULATION (LLC) HAS RAPIDLY ERODED AND SHRUNK AS IT TRACKED ACROSS THE RAGGED TERRAIN OF THE CENTRAL PHILIPPINE ISLANDS. THE INITIAL POSITION IS PLACED WITH FAIR CONFIDENCE BASED ON LOW CLOUD TRACING INTO THE LLC IN THE EIR LOOP AND TRIANGULATED FROM SURFACE WIND OBSERVATIONS OVER LEYTE AND SURIGAO ISLANDS. THE INITIAL INTENSITY OF 35KTS IS BASED ON THE DVORAK ESTIMATE OF T2.5/35KTS FROM PGTW AND THE OBJECTIVE ADT ESTIMATE OF T2.6/37KTS. ANALYSIS INDICATES WARM (29C) ALONG-TRACK SST IN THE PHILIPPINE SEA AND ROBUST WEST AND POLEWARD OUTFLOW ALOFT. RELATIVE VERTICAL WIND SHEAR IS MARGINALLY CONDUCIVE DUE TO THE STORM MOTION BEING IN-PHASE WITH THE MID AND UPPER LEVEL WIND FLOW. 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. UNDER THE STR, TS DUJUAN WILL CONTINUE TRACKING NORTHWESTWARD ACROSS THE CENTRAL PHILIPPINE ISLANDS INCLUDING LEYTE, ROMBLON, AND MINDORO, BEFORE EXITING INTO THE SOUTH CHINA SEA BY TAU 36. INCREASED RELATIVE VWS (25KTS+) COMBINED WITH THE FRICTIONAL EFFECTS OF THE RUGGED TERRAIN WILL ERODE THE TS TO DISSIPATION BY TAU 36, POSSIBLY SOONER. NUMERICAL MODELS DIVERGE SIGNIFICANTLY TO 230NM+ BY TAU 36 WITH NAVGEM ON THE RIGHT AND AEMN ON THE LEFT MARGIN OF THE ENVELOPE. THIS INDICATES UNCERTAINTY IN THE MODELS TRACKING A WEAK VORTEX, LENDING OVERALL LOW CONFIDENCE IN THE JTWC TRACK FORECAST BEYOND TAU 12.// NNNN