WDPN31 PGTW 030300
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL DEPRESSION 01W (ONE) WARNING 
NR 06//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.
   TROPICAL DEPRESSION (TD) 01W (ONE), LOCATED APPROXIMATELY 538 NM 
EAST OF HO CHI MINH CITY, VIETNAM, HAS TRACKED WEST-NORTHWESTWARD AT
18 KNOTS OVER THE PAST SIX HOURS. ANIMATED MULTISPECTRAL SATELLITE 
IMAGERY DEPICTS A PARTIALLY-EXPOSED LOW-LEVEL CIRCULATION CENTER 
(LLCC) POSITIONED ON THE SOUTHERN EDGE OF AN AREA OF DISORGANIZED, 
PERSISTENT DEEP CONVECTION. A 021935Z NOAA-19 89GHZ IMAGE REVEALS A 
WEAKLY DEFINED LLCC WITH HIGHLY DISORGANIZED DEEP CONVECTION SHEARED 
TO THE NORTH. 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 REMAINS ASSESSED AT 30 
KNOTS, HEDGED SLIGHTLY ABOVE THE DVORAK CURRENT INTENSITY ESTIMATES 
OF 1.5 (25 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 CONTINUE TRACKING 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 SST AS IT APPROACHES VIETNAM AND IS 
FORECAST TO MAKE LANDFALL NEAR TAU 36. THE SYSTEM IS EXPECTED TO 
DISSIPATE RAPIDLY AS IT TRACKS INLAND. MODEL GUIDANCE REMAINS IN 
FAIR AGREEMENT AND, WITH THE EXCEPTION OF ECMWF AND THE ECMWF 
ENSEMBLE, REMAINS VERY INCONSISTENT. OVERALL, THERE IS LOW 
CONFIDENCE IN THE JTWC FORECAST TRACK DUE TO THE LARGE SPREAD IN 
MODEL SOLUTIONS AFTER TAU 12. THE JTWC FORECAST TRACK CONTINUES TO 
FAVOR THE ECMWF SOLUTION, WHICH PROVIDES THE MOST CONSISTENT AND 
METEOROLOGICALLY SOUND SOLUTION.//
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