WDPN31 PGTW 170300
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL STORM 11W (SON-TINH) 
WARNING NR 07//
RMKS//
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.
   TROPICAL STORM 11W (SON-TINH), LOCATED APPROXIMATELY 283 NM
SOUTHEAST OF HONG KONG, HAS TRACKED WESTWARD AT 28 KNOTS OVER THE
PAST SIX HOURS. ANIMATED MULTISPECTRAL SATELLITE IMAGERY SHOWS 
FLARING CENTRAL DENSE OVERCAST COVERING THE LOW LEVEL CENTER. THE 
INITIAL POSITION IS PLACED WITH FAIR CONFIDENCE BASED ON THE MSI 
LOOP AND A 162216Z SSMIS 91GHZ MICROWAVE IMAGE. THE INITIAL 
INTENSITY OF 35 KTS IS BASED ON THE IMPROVED CONVECTIVE STRUCTURE 
AND DVORAK CURRENT INTENSITY ESTIMATES RANGING FROM T2.0 (30 KTS) TO 
T2.5 (35 KTS) FROM RJTD, PGTW, AND KNES, AND IS SLIGHTLY UNDER A 
162031Z SATCON ESTIMATE OF 43 KTS. UPPER-LEVEL ANALYSIS INDICATES 
THE SYSTEM IS IN AN AREA OF LOW TO MODERATE (10-20 KT) VWS AND THAT 
EQUATORWARD OUTFLOW IS IMPROVING. ALONG TRACK SSTS ARE HIGHLY 
CONDUCIVE AT 30 CELSIUS. OVERALL, THE ENVIRONMENT IS SLIGHTLY 
FAVORABLE FOR DEVELOPMENT. TD 11W IS TRACKING WESTWARD ALONG THE 
SOUTHERN PERIPHERY OF THE STR TO THE NORTH, AND HAS ACCELERATED AS 
IT ENTERED THE SOUTH CHINA SEA.
3. FORECAST REASONING.
   A. THERE IS NO CHANGE TO THE FORECAST PHILOSOPHY SINCE THE
PREVIOUS PROGNOSTIC REASONING MESSAGE.
   B. TD 11W IS FORECAST TO CONTINUE TRACKING QUICKLY WESTWARD. AS 
ITS FORWARD MOTION ACCELERATES, IT IS NOW EXPECTED TO MAKE LANDFALL 
ON HAINAN ISLAND IN 24 HOURS, AND IMPACT NORTHERN VIETNAM JUST AFTER 
TAU 36. THE MARGINALLY FAVORABLE ENVIRONMENT WILL PERSIST AND 
PROMOTE MODEST INTENSIFICATION, PEAKING AT 40 KTS BEFORE TAU 24, 
BEFORE IT MAKES LANDFALL ON HAINAN. AFTERWARD, LAND INTERACTION FROM 
HAINAN AND VIETNAM WILL RAPIDLY WEAKEN THE SYSTEM, LEADING TO 
DISSIPATION OVER LAND BY TAU 72. THE AVAILABLE NUMERICAL GUIDANCE IS 
IN TIGHT AGREEMENT ABOUT THE WESTWARD TRACK AND MARGINAL 
INTENSIFICATION FOLLOWED BY WEAKENING TREND, LENDING HIGH CONFIDENCE 
TO THE JTWC TRACK FORECAST.//
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