MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI// SUBJ/PROGNOSTIC REASONING FOR TROPICAL DEPRESSION 01W (ONE) WARNING NR 01// RMKS/ 1. FOR METEOROLOGISTS. 2. 6 HOUR SUMMARY AND ANALYSIS. TROPICAL DEPRESSION (TD) 01W (ONE), LOCATED APPROXIMATELY 377 NM SOUTHEAST OF MANILA, PHILIPPINES, HAS TRACKED WESTWARD AT 16 KNOTS OVER THE PAST SIX HOURS. ANIMATED ENHANCED INFRARED SATELLITE IMAGERY DEPICTS A CONSOLIDATING SYSTEM WITH A SYMMETRIC AREA OF DEEP CONVECTION OBSCURING THE LOW-LEVEL CIRCULATION CENTER (LLCC) AND IMPROVED CONVECTIVE BANDING OVER THE NORTHERN SEMI-CIRCLE. A 011829Z SSMI 85GHZ IMAGE SHOWS CURVED DEEP CONVECTIVE BANDING WRAPPING INTO THE NORTHWEST AND WEST QUADRANTS OF THE SYSTEM WITH A PARTIALLY- EXPOSED LLCC POSITIONED ON THE SOUTHEAST EDGE OF THE CENTRAL CONVECTION. THEREFORE, THERE IS FAIR CONFIDENCE IN THE INITIAL POSITION. A 011331Z ASCAT PARTIAL IMAGE REVEALED 25-30 KNOT NORTHERLY WINDS OVER THE BOHOL SEA, JUST NORTH OF MINDANAO, WHICH SUPPORTS THE INITIAL INTENSITY ASSESSMENT OF 30 KNOTS. UPPER-LEVEL ANALYSIS INDICATES A MARGINALLY FAVORABLE ENVIRONMENT WITH LOW TO MODERATE (10 TO 20 KNOTS) VERTICAL WIND SHEAR (VWS) OFFSET BY STRONG EASTERLY DIFFLUENT FLOW ALOFT. TD 01W IS TRACKING QUICKLY WESTWARD ACROSS THE PHILIPPINES UNDER THE STEERING INFLUENCE OF AN EAST-WEST ORIENTED LOW-LEVEL SUBTROPICAL RIDGE POSITIONED TO THE NORTH. 3. FORECAST REASONING. A. THIS IS THE FIRST PROGNOSTIC REASONING MESSAGE AND SETS THE FORECAST PHILOSOPHY. B. TD 01W IS FORECAST TO CONTINUE TRACKING QUICKLY WESTWARD THROUGH TAU 36 UNDER THE STEERING INFLUENCE OF THE DEEP-LAYERED LOW- TO MID-LEVEL SUBTROPICAL RIDGE (STR) ENTRENCHED TO THE NORTH. ENVIRONMENTAL CONDITIONS ARE EXPECTED TO REMAIN GENERALLY FAVORABLE THROUGH TAU 36, HOWEVER, INTERACTION WITH LAND SHOULD SLOW DEVELOPMENT WITH A PEAK INTENSITY OF 45 KNOTS FORECAST AT TAU 24 AND TAU 36 AS THE SYSTEM TRACKS OVER THE SOUTH CHINA SEA. AFTER TAU 36, TD 01W SHOULD TURN WEST-NORTHWESTWARD AND SLOW AS IT TRACKS ALONG THE WESTERN PERIPHERY OF THE STR. GRADUAL WEAKENING IS EXPECTED DUE TO INCREASING VWS AND COOLER SST (25-26C). C. AFTER THE SYSTEM MAKES LANDFALL OVER VIETNAM NEAR TAU 72, TD 01W WILL WEAKEN RAPIDLY AND SHOULD DISSIPATE BY TAU 96. DYNAMIC MODEL GUIDANCE IS IN TIGHT AGREEMENT THROUGH TAU 36 THEN RAPIDLY DIVERGES WITH GFS AND THE GFS ENSEMBLE DEPICTING AN UNLIKELY RE- CURVE NORTHWARD DIRECTLY INTO THE STR. THE JTWC FORECAST TRACK FAVORS THE ECMWF SOLUTION AND IS POSITIONED JUST WEST OF THE MULTI- MODEL CONSENSUS AT TAU 72 AND TAU 96. OVERALL, THERE IS LOW CONFIDENCE IN THE JTWC FORECAST TRACK DUE TO UNCERTAINTY IN THE INITIAL POSITION AND THE LARGE SPREAD IN MODEL SOLUTIONS AFTER TAU 36.// NNNN NNNN