MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI// SUBJ/PROGNOSTIC REASONING FOR TROPICAL DEPRESSION 01W (ONE) WARNING NR 09// RMKS/ 1. FOR METEOROLOGISTS. 2. 6 HOUR SUMMARY AND ANALYSIS. TROPICAL DEPRESSION (TD) 01W (ONE), LOCATED APPROXIMATELY 162 NM EAST-SOUTHEAST OF HO CHI MINH CITY, VIETNAM, HAS TRACKED WEST- NORTHWESTWARD AT 04 KNOTS OVER THE PAST SIX HOURS. ANIMATED MULTISPECTRAL SATELLITE IMAGERY AND A 150154Z ASCAT PASS DEPICT A LOOSELY ORGANIZED LOW LEVEL CIRCULATION CENTER (LLCC) WITH 25 TO 30 KNOT WINDS FOUND TO THE NORTH AND WEST WITHIN THE BULK OF CONVECTION. HOWEVER, THE CONVECTION HAS WANED OVER THE PAST SIX HOURS, LEAVING THE LLCC MOSTLY EXPOSED THEREFORE PROVIDING GOOD CONFIDENCE IN THE CURRENT POSITION. THE INTENSITY HAS BEEN HELD AT 30 KNOTS BASED ON THE ASCAT DATA AND AN UNCHANGED DVORAK INTENSITY ESTIMATE OF T1.5 (25 KNOTS) FROM PGTW. TD 01W REMAINS IN A MARGINAL ENVIRONMENT WITH 15 TO 25 KNOT SOUTHEASTERLY VERTICAL WIND SHEAR OFFSETTING THE DIVERGENT POLEWARD OUTFLOW. ADDITIONALLY, DRY AIR LOCATED TO THE SOUTH AND EAST IS PREVENTING SUSTAINED CONVECTION. TD 01W IS DRIFTING SLOWLY WESTWARD ALONG THE SOUTHERN PERIPHERY OF THE LOW- TO MID-LEVEL SUB-TROPICAL RIDGE POSITIONED TO THE NORTH. 3. FORECAST REASONING. A. NO CHANGE TO THE FORECAST PHILOSOPHY SINCE THE PREVIOUS PROGNOSTIC REASONING MESSAGE. B. TD 01W WILL CONTINUE TO TRACK WESTWARD TO WEST-SOUTHWESTWARD THROUGH THE FORECAST PERIOD. THE CYCLONE WILL MAKE LANDFALL OVER THE SOUTHERN TIP OF VIETNAM IN THE NEXT 24 HOURS. THE SYSTEM WILL MAINTAIN CURRENTLY INTENSITY AS IT APPROACHES LAND AND THEN BEGIN TO DISSIPATE DUE TO LAND INTERACTION. AVAILABLE DYNAMIC MODEL GUIDANCE IS IN GOOD AGREEMENT, THEREFORE, THERE IS HIGH CONFIDENCE IN THE JTWC FORECAST TRACK.// NNNN NNNN