MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI// SUBJ/PROGNOSTIC REASONING FOR TROPICAL DEPRESSION 01W (ONE) WARNING NR 05// RMKS/ 1. FOR METEOROLOGISTS. 2. 6 HOUR SUMMARY AND ANALYSIS. TROPICAL DEPRESSION (TD) 01W (ONE), LOCATED APPROXIMATELY 369 NM SOUTHWEST OF MANILA, PHILIPPINES, HAS TRACKED WESTWARD AT 17 KNOTS OVER THE PAST SIX HOURS. ANIMATED ENHANCED INFRARED SATELLITE IMAGERY DEPICTS AN EXPOSED LOW-LEVEL CIRCULATION CENTER (LLCC) WITH DISORGANIZED, PERSISTENT DEEP CONVECTION OVER THE NORTHWEST QUADRANT. A 021821Z GMI 89GHZ IMAGE REVEALS SHALLOW BANDING WRAPPING INTO A DEFINED LLCC, WHICH SUPPORTS THE INITIAL POSITION WITH FAIR CONFIDENCE. UPPER-LEVEL ANALYSIS INDICATES A MARGINAL ENVIRONMENT WITH LOW TO MODERATE (15 TO 20 KNOTS) VERTICAL WIND SHEAR (VWS) AND BROAD DIFFLUENCE. CONSEQUENTLY, TD 01W HAS STRUGGLED TO ORGANIZE BUT HAS MAINTAINED AN INITIAL INTENSITY OF 30 KNOTS, WHICH IS SUPPORTED BY SURFACE OBSERVATIONS FROM PUERTO PRINCESA, PHILIPPINES, SHOWING 27 KNOT SUSTAINED WINDS (10 MINUTE MEAN). 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 UNDER THE INFLUENCE OF THE STR WHICH IS LOCATED TO THE NORTH AND SHOULD MAINTAIN INTENSITY AT 30 KNOTS THROUGH TAU 24. AFTER TAU 24, 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.// NNNN NNNN