MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI// SUBJ/PROGNOSTIC REASONING FOR TROPICAL DEPRESSION 36W (THIRTYSIX) WARNING NR 001// RMKS/ 1. FOR METEOROLOGISTS. 2. 6 HOUR SUMMARY AND ANALYSIS. TROPICAL DEPRESSION (TD) 35W (THIRTYFIVE), LOCATED APPROXIMATELY 375 NM EAST-SOUTHEAST OF HO CHI MINH CITY, VIETNAM, HAS TRACKED WESTWARD AT 10 KNOTS OVER THE PAST SIX HOURS. ANIMATED MULTISPECTRAL SATELLITE IMAGERY (MSI) SHOWS A CONSOLIDATING SYSTEM WITH FLARING CONVECTION SLIGHTLY SHEARED NORTHWESTWARD OF THE LOW LEVEL CIRCULATION (LLC). FORMATIVE BANDS ALONG THE SOUTHERN FLANK CAN BE SEEN FEEDING INTO THE LLC. THE INITIAL POSITION IS PLACED WITH FAIR CONFIDENCE BASED ON THE MSI LOOP. THE INITIAL INTENSITY OF 25 KNOTS IS BASED ON THE DVORAK ESTIMATE OF T1.5/25KTS FROM PGTW. UPPER LEVEL ANALYSIS INDICATES THE SYSTEM IS IN AN AREA OF MODERATE (20-25 KNOTS) SOUTHEASTERLY VERTICAL WIND SHEAR (VWS) OFFSET BY EXCELLENT POLEWARD OUTFLOW. SEA SURFACE TEMPERATURES IN THE SOUTH CHINA SEA AND INTO THE GULF OF THAILAND ARE VERY CONDUCIVE AT 28-29 CELSIUS. TD 35W IS TRACKING ALONG THE SOUTHEASTERN PERIPHERY OF A SUBTROPICAL RIDGE (STR) ANCHORED TO THE NORTHWEST. 3. FORECAST REASONING. A. THIS IS THE INITIAL PROGNOSTIC REASONING MESSAGE ON THIS SYSTEM AND SETS THE FORECAST PHILOSOPHY. B. TD 36W IS EXPECTED TO TRACK SOUTHWESTWARD THEN NORTHWESTWARD TOWARD THE GULF OF THAILAND AROUND THE SOUTHERN PERIPHERY OF THE STR. THE VWS IS EXPECTED TO DECREASE AND ALLOW A MODEST INTENSIFICATION TO A PEAK OF 45 KNOTS BY TAU 72 AS IT ENTERS THE GULF OF THAILAND. C. AFTER TAU 72, VWS WILL ONCE AGAIN PICK UP. THIS, IN ADDITION TO LAND INTERACTION AS TD 35W CROSSES THE MALAY PENINSULA AFTER TAU 96 WILL CAUSE A STEADY WEAKENING DOWN TO 30 KNOTS BY TAU 120. THE AVAILABLE NUMERICAL GUIDANCE IS IN FAIRLY GOOD AGREEMENT WITH GRADUAL SPREADING TO 250 NM BY TAU 120 WITH HWRF ON THE LEFT AND NAVGEM ON THE RIGHT MARGIN OF THE MODEL ENVELOPE. HOWEVER, DUE TO THE FORMATIVE NATURE OF THE SYSTEM, THERE IS LOW CONFIDENCE IN THIS INITIAL JTWC TRACK FORECAST THAT IS LAID CLOSE TO THE MODEL CONSENSUS.// NNNN NNNN