WDPN31 PGTW 202100
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL DEPRESSION 01W (DUJUAN) 
WARNING NR 015//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.
   TROPICAL DEPRESSION (TD) 01W (DUJUAN), LOCATED 658 NM SOUTHEAST 
OF MANILA, PHILIPPINES, HAS TRACKED WESTWARD AT 13 KNOTS OVER THE 
PAST SIX HOURS. ANIMATED ENHANCED INFRARED (EIR) SATELLITE IMAGERY 
SHOWS A RAGGED LOW LEVEL CIRCULATION (LLC), INITIAL POSITION IS 
PLACED WITH FAIR CONFIDENCE BASED ON THE EIR LOOP. THE INITIAL 
INTENSITY OF 30KTS IS BASED ON DVORAK ESTIMATES OF T2.0/30KTS 
(PGTW/RJTD) AND SUPPORTED BY THE ADVANCED DVORAK TECHNIQUE (ADT) 
OBJECTIVE ESTIMATE OF T2.4/34KTS. ANALYSIS INDICATES WARM (29-30C) 
ALONG-TRACK SST AND ROBUST WEST AND POLEWARD OUTFLOW ALOFT. 
ADDITIONALLY, THE WARM MOIST AIR AHEAD OF THE TD IS OVERRUNNING THE 
COLD NORTHEASTERLY WIND SURGE IN THE PHILIPPINE SEA. DEEP CONVECTION 
REMAINS AHEAD OF THE DISPLACED LLC BY HIGH (30KT) SOUTHEASTERLY 
VERTICAL WIND SHEAR (VWS). THE CYCLONE IS NOW TRACKING NORTHWESTWARD 
AS THE SUBTROPICAL RIDGE (STR) STEERS IT TOWARDS THE PHILIPPINE 
ISLANDS.   
3. FORECAST REASONING.
   A. THERE IS NO SIGNIFICANT CHANGE IN THE FORECAST PHILOSOPHY FROM 
THE PREVIOUS PROGNOSTIC REASONING MESSAGE.
   B. TD 01W WILL CONTINUE TRACKING NORTHWESTWARD AS THE STEERING 
STR TO THE NORTHEAST BUILDS, THE SYSTEM WILL MAKE INITIAL LANDFALL 
OVER SAMAR, PHILIPPINES, JUST AFTER TAU 24 AND THEN ENTER THE 
SIBUYAN SEA AND ENCOUNTER COOLER 27C SSTS. AFTER TAU 24, HIGH 
RELATIVE VWS COMBINED WITH THE RUGGED TERRAIN OF THE MULTIPLE 
ISLANDS 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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