MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI// SUBJ/PROGNOSTIC REASONING FOR TROPICAL STORM 13W (PODUL) WARNING NR 10// RMKS/ 1. FOR METEOROLOGISTS. 2. 6 HOUR SUMMARY AND ANALYSIS. TROPICAL STORM (TS) 13W (PODUL), LOCATED APPROXIMATELY 316 NM EAST OF HUE, VIETNAM, HAS TRACKED WESTWARD AT 10 KNOTS (KTS) OVER THE PAST SIX HOURS. ANIMATED ENHANCED INFRARED SATELLITE (EIR) IMAGERY SHOWS THE CENTRAL CONVECTION DISPLACED APPROXIMATELY 70NM SOUTHWESTWARD OF THE PARTIALLY EXPOSED LOW LEVEL CIRCULATION (LLC). THE INITIAL POSITION IS PLACED WITH FAIR CONFIDENCE BASED ON THE PARTIALLY EXPOSED LLC IN THE EIR LOOP AND MOSTLY CONCENTRIC WITH AN LLC FEATURE IN A COMPOSITE RADAR REFLECTIVITY LOOP FROM CMA. THE INITIAL INTENSITY OF 35 KNOTS IS BASED ON MULTI-AGENCY DVORAK ESTIMATES OF T2.5/35KTS AND IS CONSISTENT WITH NEARBY SURFACE OBSERVATIONS INCLUDING THOSE FROM XISHA DAO, APPROXIMATELY 72NM TO THE WEST-SOUTHWEST. THE ENVIRONMENT IS MARGINAL AT BEST WITH UNFAVORABLY STRONG (25-30 KT) VERTICAL WIND SHEAR (VWS) OFFSETTING FAVORABLE WESTWARD OUTFLOW, IN-PHASE STORM MOTION, AND WARM SEA SURFACE TEMPERATURES (29-30 CELSIUS). TS 13W IS TRACKING ALONG THE SOUTHERN 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 13W WILL CONTINUE TRACKING WEST-NORTHWESTWARD UNDER THE STEERING INFLUENCE OF THE STR UNTIL MAKING LANDFALL OVER NORTH CENTRAL VIETNAM SHORTLY AFTER TAU 30. MARGINAL ENVIRONMENTAL CONDITIONS WILL SUSTAIN THE INTENSITY UP TO 12 HOURS THEN GRADUALLY WEAKEN PRIOR TO LANDFALL. AFTERWARD, THE SYSTEM WILL RAPIDLY ERODE AND SHOULD DISSIPATE DUE TO LAND INTERACTION NO LATER THAN TAU 48. MODEL GUIDANCE IS IN GOOD AGREEMENT WITH NAVGEM AS THE NOTABLE RIGHT-OF-TRACK OUTLIER. THE JTWC TRACK FORECAST IS LAID WITH FAIR CONFIDENCE JUST LEFT OF AND SLOWER THAN CONSENSUS TO OFFSET NAVGEMS UNLIKELY POLEWARD TRACK TOWARD THE STR.// NNNN NNNN