WDPN31 PGTW 151500
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL STORM 01W (VONGFONG) WARNING 
NR 016//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.
   TROPICAL STORM (TS) 01W (VONGFONG), LOCATED APPROXIMATELY 38 NM 
NORTHEAST OF MANILA, PHILIPPINES, HAS TRACKED NORTH-NORTHWESTWARD AT 
11 KNOTS OVER THE PAST SIX HOURS. ANIMATED ENHANCED INFRARED 
SATELLITE IMAGERY (EIR) SHOWS A COMPACT SYSTEM WITH A TIGHT CORE OF 
DENSE CONVECTION.  THE INITIAL INTENSITY IS ASSESED AT 55 KNOTS WITH 
FAIR CONFIDENCE BASED ON MULTI-AGENCY DVORAK INTENSITY ESTIMATES 
RANGING FROM T3.0-T4.0 (45-65 KNOTS) FROM PGTW, RJTD AND RCTP. THE 
INITIAL POSITION IS BASED WITH GOOD CONFIDENCE ON A DECAYING 
MICROWAVE EYE SEEN IN A 151036Z SSMIS 91GHZ PASS. ENVIRONMENTAL 
PARAMETERS REMAIN WITH A STRONG POLEWARD OUTFLOW CHANNEL, NEARBY 
WARM (30-31 DEGREES CELSIUS) SEA SURFACE TEMPERATURES (SST) AND LOW 
(10-15 KT) VERTICAL WIND SHEAR (VWS). TS 01W IS TRACKING ALONG THE 
WESTERN PERIPHERY OF A SUBTROPICAL RIDGE (STR) TO THE EAST. 
3. FORECAST REASONING.
   A. THERE HAS BEEN NO SIGNIFICANT CHANGE TO THE FORECAST 
PHILOSOPHY. 
   B. TS 01W IS FORECAST TO TRACK NORTHWARD ALONG THE WESTERN 
PERIPHERY OF THE STEERING STR THROUGH TAU 24. AN UPPER-LEVEL TROUGH 
TO THE NORTH WILL PASS BETWEEN TAU 12-24, ERODING THE STR AND 
FORCING IT TO RECEDE EASTWARD. THIS WILL ALLOW 01W TO GRADUALLY 
ROUND THE STR AXIS BETWEEN TAU 12-24. WITH THE EXCEPTION OF AFUM, 
NUMERICAL MODEL GUIDANCE IS IN GOOD AGREEMENT WITH A CROSS TRACK 
SPREAD OF 70NM AT TAU 48. HOWEVER, THERE IS SIGNIFICANT PROPAGATION 
SPEED DIFFERENCES BETWEEN MODEL SOLUTIONS AS TS 01W RECURVES AROUND 
THE STR. TS 01W IS EXPECTED TO WEAKEN SIGNIFICANTLY AS IT TRACKS 
OVER LAND DESPITE ITS FAVORABLE UPPER LEVEL ENVIRONMENT. TS 01W WILL 
EMERGE OVER 28-30 DEGREE CELSIUS SEA SURFACE TEMPERATURE WATER BY 
TAU 24. HOWEVER, STRONG VWS WILL HAMPER FURTHER INTENSIFICATION. 
AFTER TAU 36, TS 01W WILL BEGIN TO ACCELERATE NORTHEASTWARD.//
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