WDPN31 PGTW 300300
MSGID/GENADMIN/NAVMARFCSTCEN PEARL HARBOR HI/JTWC//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL STORM 20W (NESAT) WARNING NR 
27//
RMKS/
1. FOR METEOROLOGISTS.
2. 12 HOUR SUMMARY AND ANALYSIS.
   A. TROPICAL STORM (TS) 20W (NESAT), LOCATED APPROXIMATELY 100 NM 
EAST OF 
HANOI, VIETNAM, HAS TRACKED WEST-NORTHWESTWARD AT 13 KNOTS OVER THE 
PAST SIX 
HOURS. ANIMATED MULTISPECTRAL SATELLITE IMAGERY INDICATES THAT TS 
20W IS APPROACHING LANDFALL IN THE HAI PHONG-CAM PHA AREA. THE 
SYSTEM IS MAINTAINING VIGOROUS CONVECTION BUT OBSERVATIONS FROM 
HANOI (VVNB) INDICATE THAT THE AREA OF 35 KNOT WINDS HAS CONTRACTED 
SIGNIFICANTLY. THICK CONVECTIVE BANDING AND AN EXPANDING AREA OF 
COLD TOPS ON INFRARED IMAGERY INDICATE TS 22W IS GENERATING HEAVY 
RAINS OVER A WIDESPREAD AREA. TS 20W HAS ACCELERATED ALONG TRACK AND 
IS NOW ON PACE TO COME ASHORE WITHIN THE NEXT SIX HOURS. 
3. A. THE FORECAST PHILOSOPHY HAS NOT CHANGED. 
   B. TS 20W WILL STEER ALONG THE SOUTHWESTERN PERIMETER OF A MID- 
TO UPPER LEVEL ANTICYCLONE AND THE SYSTEM WILL DISSIPATE AS A 
SIGNIFICANT TROPICAL CYCLONE WITHIN THE NEXT 24 HOURS. LAND 
INTERACTION WILL BE THE PRIMARY WEAKENING MECHANISM, AS VERTICAL 
WIND SHEAR WILL REMAIN BELOW 10 KNOTS. THE LATEST GUIDANCE INDICATES 
THAT THE STORM WILL TRACK NORTH OF HANOI. A TRACK THAT STEERS THE 
REMAINING LOW LEVEL CIRCULATION CENTER THROUGH THE RUGGED TERRAIN 
NORTH OF HANOI RATHER THAN THROUGH THE RED RIVER DELTA WILL HASTEN 
THE WEAKENING PROCESS. ALTHOUGH IT WILL GENERATE A SEVERE RAIN 
EVENT, TS 20W WILL DISSIPATE OVER LAND BY TAU 24.//
NNNN