WDPN31 PGTW 201500 MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI// SUBJ/PROGNOSTIC REASONING FOR TROPICAL DEPRESSION 01W (DUJUAN) WARNING NR 014// RMKS/ 1. FOR METEOROLOGISTS. 2. 6 HOUR SUMMARY AND ANALYSIS. TROPICAL DEPRESSION (TD) 01W (DUJUAN), LOCATED 724 NM EAST- SOUTHEAST OF MANILA, PHILIPPINES, HAS TRACKED NORTH-NORTHWESTWARD AT 10 KNOTS OVER THE PAST SIX HOURS. ANIMATED ENHANCED INFRARED (EIR) SATELLITE IMAGERY SHOWS A PARTLY EXPOSED, RAGGED, LOW LEVEL CIRCULATION (LLC) THAT IS DECOUPLED 100NM+ SOUTHEASTWARD FROM THE MAIN CONVECTION. A SMALL BALL OF CONVECTION HAS MOMENTARILY FLARED UP IN BETWEEN (30NM TO THE NORTHWEST) BUT HAS SINCE WANED. INITIAL POSITION IS PLACED WITH FAIR CONFIDENCE BASED ON THE LLC IN THE EIR LOOP. THE INITIAL INTENSITY OF 30KTS IS BASED ON DVORAK ESTIMATES OF T2.0/30KTS (PGTW/RJTD) AND SUPPORTED BY THE ADT OBJECTIVE ESTIMATE OF T2.2/32KTS. ANALYSIS INDICATES WARM (29-30C) ALONG-TRACK SST AND STRONG WESTWARD AND POLEWARD OUTFLOW ALOFT. ADDITIONALLY, THE WARM MOIST AIR AHEAD OF THE TD IS OVERRUNNING THE COLD NORTHEASTERLY WIND SURGE IN THE PHILIPPINE SEA. THIS COMBINATION IS FUELING THE DEEP/EXPANSIVE MAIN CONVECTION EVEN THOUGH IT IS DISPLACED BY HIGH (30KT) SOUTHEASTERLY VERTICAL WIND SHEAR (VWS). THE CYCLONE HAS BEGUN TO TRACK POLEWARD ALONG THE SOUTHWESTERN PERIPHERY OF THE DEEP LAYERED SUBTROPICAL RIDGE (STR) TO THE NORTHEAST. 3. FORECAST REASONING. A. THERE IS NO SIGNIFICANT CHANGE IN THE FORECAST PHILOSOPHY FROM THE PREVIOUS PROGNOSTIC REASONING MESSAGE. B. TD 01W WILL TRACK MORE NORTHWESTWARD AS THE STEERING STR TO THE NORTHEAST BUILDS, MAKING LANDFALL OVER SAMAR, PHILIPPINES, AFTER TAU 30. AS THE STORM MOTION BECOMES MORE IN-PHASE WITH THE UPPER LEVEL WIND FLOW, THE VWS WILL RELAX A BIT AND MAY ALLOW A SLIGHT INTENSIFICATION TO 35KTS BY TAU 12. AFTERWARD, INCREASED RELATIVE VWS, AS THE TD INTERACTS WITH THE COLD NORTHEASTERLY WIND SURGE WILL WEAKEN THE TD TO 30KTS BY TAU 24. AFTER TAU 24, THE ADDITION OF LAND INTERACTION TO THE HIGH VWS WILL ERODE THE TD TO DISSIPATION BY TAU 48, POSSIBLY SOONER. NUMERICAL MODELS DIVERGE SIGNIFICANTLY TO 250NM+ BY TAU 48. THIS INDICATES UNCERTAINTY IN THE MODELS TRACKING A WEAK VORTEX, LENDING OVERALL LOW CONFIDENCE IN THE JTWC TRACK FORECAST.// NNNN