WDPN31 PGTW 031500
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL DEPRESSION 01W (BOLAVEN) 
WARNING NR 08//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.
   TROPICAL DEPRESSION (TD) 01W (BOLAVEN), LOCATED APPROXIMATELY 391 
NM EAST OF HO CHI MINH CITY, VIETNAM, HAS TRACKED WEST-NORTHWESTWARD 
AT 16 KNOTS OVER THE PAST SIX HOURS. ANIMATED INFRARED SATELLITE 
IMAGERY DEPICTS FLARING CONVECTION TO THE NORTHWEST OF THE LOW LEVEL
CIRCULATION CENTER (LLCC) ASSOCIATED WITH TD 01W. A 031035Z 91 GHZ
SSMIS MICROWAVE IMAGE SHOWS THE AFOREMENTIONED CONVECTION AND WEAK
BANDING FEATURES AROUND THE LLCC. UPPER-LEVEL ANALYSIS INDICATES A
MARGINAL ENVIRONMENT WITH LOW TO MODERATE (15 TO 20 KNOT) VERTICAL
WIND SHEAR (VWS) AND BROAD DIFFLUENCE. THE INITIAL INTENSITY REMAINS
ASSESSED 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 WEST-NORTHWESTWARD UNDER THE
STEERING INFLUENCE OF THE STR WHICH IS LOCATED TO THE NORTH AND WILL
WEAKEN TO 25 KNOTS BY TAU 12. AFTER TAU 12, TD 01W WILL CONTINUE TO
WEAKEN DUE TO PERSISTENT VWS AND COOLER SEA SURFACE TEMPERATURES AS
IT APPROACHES VIETNAM. TD 01W IS FORECAST TO MAKE LANDFALL SHORTLY
BEFORE 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