WDPN31 PGTW 012100
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL DEPRESSION 04W (CHOI-WAN) 
WARNING NR 013//
RMKS//
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.
   TROPICAL DEPRESSION (TD) 04W (CHOI-WAN), LOCATED APPROXIMATELY 
239 NM SOUTHEAST OF MANILA, PHILIPPINES, HAS TRACKED WESTWARD 
AT 14 KNOTS OVER THE PAST SIX HOURS. ANIMATED ENHANCED INFRARED 
(EIR) SATELLITE IMAGERY DEPICTS A DISORGANIZED LOW-LEVEL CIRCULATION 
(LLC) WITH DEEP CONVECTION BEING SHEARED TO THE SOUTHWEST OF THE 
CENTER. THE INITIAL POSITION IS PLACED WITH LOW CONFIDENCE BASED ON 
RADAR IMAGERY AND SURFACE OBSERVATIONS. THE INITIAL INTENSITY 
REMAINS AT 30 KNOTS, WHICH IS IN LINE WITH THE RJTD DVORAK CURRENT 
INTENSITY ESTIMATE OF 2.0 (30KTS) AND AN ADT CURRENT INTENSITY 
ESTIMATE OF 2.2 (32 KTS). TD 04W IS CURRENTLY IN A MARGINAL 
ENVIRONMENT FOR FURTHER DEVELOPMENT WITH MODERATE TO HIGH (15-25 
KTS) VWS AND CONVERGENT FLOW ALOFT DUE TO AN UPPER LEVEL TROUGH. 
HOWEVER, THERE IS GOOD EQUATORWARD OUTFLOW AND WARM (30C) SSTS 
SUSTAINING THE SYSTEM. TD 04W IS TRACKING WESTWARD ALONG THE 
SOUTHWEST EDGE OF THE A SUBTROPICAL RIDGE TO THE NORTH AND NORTHEAST.
3. FORECAST REASONING.
   A. THERE IS NO CHANGE TO THE FORECAST PHILOSOPHY.  
   B. TD 04W IS FORECAST TO BEGIN TURNING NORTHWESTWARD AND REACH AN 
INTENSITY OF 35KTS OVER THE SIBUYAN SEA JUST BEFORE MAKING LANDFALL 
OVER LUZON AND PASSING SLIGHTLY TO THE WEST OF MANILA JUST BEFORE 
TAU 24. THE MOUNTAINOUS TERRAIN OF NORTHERN LUZON WILL DISRUPT THE 
LOW LEVEL CIRCULATION, WEAKENING THE SYSTEM TO 30 KTS AS IT 
REEMERGES OVER WATER UNDER UPPER-LEVEL EASTERLIES AND MODERATE VWS. 
THIS WEAKENING TREND WILL CONTINUE AS TD 04W RECURVES NORTH-
NORTHEASTWARD AT TAU 48 AND TRACKS INTO THE WESTERLIES BY TAU 72, 
WHICH FURTHER DISSIPATE THE SYSTEM. THE JTWC FORECAST TRACK LIES 
SLIGHTLY WEST OF THE MULTI-MODEL CONSENSUS THROUGHOUT THE FORECAST 
PERIOD, BUT DUE TO THE UNCERTAINTY OF THE IMPACT OF THE LAND 
INTERACTION, THERE IS LOW CONFIDENCE IN BOTH THE JTWC FORECAST TRACK 
AND INTENSITY.//
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