WDPN32 PGTW 131500
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL STORM 21W (DOKSURI) 
WARNING NR 08//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.
   TROPICAL STORM 21W (DOKSURI), LOCATED APPROXIMATELY 359 NM EAST OF
DA NANG, VIETNAM, HAS TRACKED WEST-NORTHWESTWARD AT 14 KNOTS OVER
THE PAST SIX HOURS. ANIMATED ENHANCED INFRARED SATELLITE IMAGERY 
SHOWS FRAGMENTED BUT DEEP CONVECTIVE BANDS FEEDING INTO A WELL-
DEFINED LOW LEVEL CIRCULATION. THE INITIAL POSITION IS PLACED WITH 
HIGH CONFIDENCE BASED ON A LOW REFLECTIVITY CIRCULATION FEATURE IN 
THE 1116Z AMSUB MICROWAVE PASS. THE INITIAL INTENSITY OF 45 KNOTS IS
BASED ON DVORAK ESTIMATE OF T3.0 FROM RJTD AND PGTW. ENVIRONMENTAL
ANALYSIS INDICATES THE SYSTEM IS IN AN AREA OF LOW (10-15 KNOT)
VERTICAL WIND SHEAR (VWS), GOOD EQUATORWARD OUTFLOW, AND IS DRIFTING
OVER VERY WARM (29-30 CELSIUS) SEA SURFACE TEMPERATURES (SSTS). TS
21W IS TRACKING UNDER THE INFLUENCE OF AN EXTENSION OF THE
SUBTROPICAL RIDGE (STR) TO THE NORTHEAST.
3. FORECAST REASONING.
   A. THERE IS NO SIGNIFICANT CHANGE TO THE FORECAST PHILOSOPHY FROM
THE PREVIOUS PROGNOSTIC REASONING MESSAGE.
   B. TS DOKSURI WILL CONTINUE TO TRACK WEST-NORTHWESTWARD IN THE 
SOUTH CHINA SEA UNDER THE INFLUENCE OF THE STR THROUGHOUT THE 
FORECAST. BY TAU 36, THE CYCLONE WILL REACH THE GULF OF TONKIN AND 
POISED TO MAKE LANDFALL INTO NORTHERN VIETNAM. THE FAVORABLE 
ENVIRONMENT WILL ALLOW FOR STEADY INTENSIFICATION, PEAKING AT 75 
KNOTS BY TAU 36. AFTER LANDFALL, THE SYSTEM WILL RAPIDLY ERODE AND 
DISSIPATE BY TAU 72 OVER THE MOUNTAINS OF NORTHERN THAILAND. DYNAMIC 
MODEL GUIDANCE REMAINS IN TIGHT AGREEMENT, LENDING HIGH CONFIDENCE 
IN THE JTWC TRACK FORECAST.//
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