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.//
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