MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI// SUBJ/PROGNOSTIC REASONING FOR TROPICAL DEPRESSION 01W (BOLAVEN) WARNING NR 07// RMKS/ 1. FOR METEOROLOGISTS. 2. 6 HOUR SUMMARY AND ANALYSIS. TROPICAL DEPRESSION (TD) 01W (BOLAVEN), LOCATED APPROXIMATELY 477 NM EAST OF HO CHI MINH CITY, VIETNAM, HAS TRACKED NORTHWESTWARD AT 13 KNOTS OVER THE PAST SIX HOURS. ANIMATED MULTISPECTRAL SATELLITE IMAGERY DEPICTS A PARTIALLY EXPOSED LOW LEVEL CIRCULATION CENTER (LLCC) POSITIONED ON THE SOUTHEASTERN EDGE OF AN AREA OF DISORGANIZED, PERSISTENT DEEP CONVECTION. A 030600Z HIMAWARI VISIBLE SATELLITE IMAGE SHOWS THE AFOREMENTIONED LLCC WITH CONVECTION LOCATED TO THE NORTHWEST. UPPER-LEVEL ANALYSIS INDICATES A MARGINAL ENVIRONMENT WITH LOW TO MODERATE (15 TO 20 KNOTS) VERTICAL WIND SHEAR (VWS) AND BROAD DIFFLUENCE. THE INITIAL INTENSITY ASSESSMENT REMAINS AT 30 KNOTS BASED ON AN RJTD DVORAK ESTIMATE OF T2.0 (30 KNOTS). SEA SURFACE TEMPERATURES REMAIN FAVORABLE, NEAR 27 DEGREES CELSIUS. TD 01W IS TRACKING WESTWARD UNDER THE STEERING INFLUENCE OF AN EAST-WEST ORIENTED SUBTROPICAL RIDGE (STR) POSITIONED TO THE NORTH. 3. FORECAST REASONING. A. THERE IS NO CHANGE IN THE FORECAST PHILOSOPHY SINCE THE PREVIOUS PROGNOSTIC REASONING MESSAGE. B. TD 01W IS FORECAST TO TRACK WESTWARD TO WEST-NORTHWESTWARD UNDER THE STEERING INFLUENCE OF THE STR WHICH IS LOCATED TO THE NORTH AND SHOULD MAINTAIN INTENSITY AT 30 KNOTS THROUGH TAU 12. AFTER TAU 12, TD 01W WILL WEAKEN GRADUALLY DUE TO PERSISTENT VWS AND COOLER SEA SURFACE TEMPERATURES AS IT APPROACHES VIETNAM. TD 01W IS FORECAST TO MAKE LANDFALL SHORTLY AFTER TAU 24. THE SYSTEM IS EXPECTED TO DISSIPATE RAPIDLY AS IT TRACKS INLAND. NUMERICAL MODEL GUIDANCE REMAINS IN FAIR AGREEMENT THROUGH TAU 12 WITH INCREASED SPREADING IN MODEL GUIDANCE BEYOND TAU 12. OVERALL, THERE IS LOW CONFIDENCE IN THE JTWC FORECAST TRACK DUE TO THE LARGE SPREAD IN MODEL SOLUTIONS AFTER TAU 12.// NNNN NNNN