MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI// SUBJ/PROGNOSTIC REASONING FOR TROPICAL STORM 13W (THIRTEEN) WARNING NR 003// RMKS/ 1. FOR METEOROLOGISTS. 2. 6 HOUR SUMMARY AND ANALYSIS. TROPICAL STORM (TS) 13W (THIRTEEN), LOCATED APPROXIMATELY 218 NM WEST-SOUTHWEST OF MANILA, PHILIPPINES, HAS TRACKED WEST NORTHWESTWARD AT 08 KNOTS OVER THE PAST SIX HOURS. ANIMATED MULTISPECTRAL SATELLITE IMAGERY SHOWS THE SYSTEM CONTINUED TO SLOWLY CONSOLIDATE AS FORMATIVE BANDING WRAPPED TIGHTER INTO THE LOW LEVEL CIRCULATION (LLC) THAT REMAINS OBSCURED BY A DEEPENING CENTRAL CONVECTION. THE INITIAL POSITION IS PLACED WITH FAIR CONFIDENCE BASED ON A LLC FEATURE IN THE 2023Z SSMIS MICROWAVE IMAGE. THE INITIAL INTENSITY OF 40 KTS IS HELD HIGHER THAN AGENCY DVORAK ESTIMATES AND MORE IN LINE WITH THE ADT ESTIMATE OF T2.9/43KTS TO REFLECT THE IMPROVED STRUCTURE. ANALYSIS INDICATES A FAVORABLE ENVIRONMENT WITH VERY WARM (30-32C) SEA SURFACE TEMPERATURES, MODERATE WESTWARD/EQUATORWARD OUTFLOW, AND MODERATE 15-20KT VERTICAL WIND SHEAR THAT IS MITIGATED BY THE STORM MOTION THAT IS IN-PHASE WITH THE UPPER LEVEL WIND FLOW. THE CYCLONE IS TRACKING ALONG THE SOUTHERN PERIPHERY OF THE SUBTROPICAL RIDGE (STR) TO THE NORTHEAST. 3. FORECAST REASONING. A. THERE IS NO SIGNIFICANT CHANGE TO THE FORECAST PHILOSOPHY FROM THE PREVIOUS PROGNOSTIC REASONING MESSAGE. B. UNDER THE STEERING STR, TS 13W WILL TRACK GENERALLY WEST- NORTHWESTWARD THROUGHOUT THE FORECAST PERIOD ACROSS THE SOUTH CHINA SEA, MAKE LANDFALL OVER CENTRAL VIETNAM NEAR HUE, VIETNAM AROUND TAU 54, THEN DRAG DEEP INTO THE INDOCHINA PENINSULA THROUGH LAOS AND CROSS INTO THAILAND BY TAU 72. THE FAVORABLE ENVIRONMENT WILL PROMOTE STEADY INTENSIFICATION TO A PEAK OF 70 KNOTS BY TAU 48. AFTERWARD, LAND INTERACTION AND INCREASING VWS WILL RAPIDLY ERODE THE SYSTEM DOWN TO 35 KNOTS BY TAU 72. C. AFTER TAU 72, TS 13W WILL CONTINUE TO DETERIORATE AS IT DRAGS ACROSS THE MOUNTAINOUS TERRAIN OF NORTHERN THAILAND, LEADING TO DISSIPATION AFTER IT CROSSES INTO MYANMAR. NUMERICAL MODELS ARE IN GOOD AGREEMENT WITH MINIMAL SPREADING TO 240NM AT TAU 72 LENDING HIGH CONFIDENCE IN THE JTWC FORECAST TRACK.// NNNN NNNN