WDPN31 PGTW 101500
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL STORM 30W (HAIKUI) 
WARNING NR 07//
RMKS//
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.
   TROPICAL STORM (TS) 30W (HAIKUI), LOCATED APPROXIMATELY 380 NM 
SOUTH-SOUTHEAST OF HONG KONG, HAS TRACKED NORTHWESTWARD AT 11 KNOTS
OVER THE PAST SIX HOURS. ANIMATED ENHANCED INFRARED SATELLITE 
IMAGERY DEPICTS AN AREA OF INTENSE DEEP CONVECTION (CLOUD TOP 
TEMPERATURE -82C) OBSCURING THE LOW-LEVEL CIRCULATION CENTER. A 
101048Z SSMIS 91GHZ COMPOSITE IMAGE SHOWS RAGGED BANDING SURROUNDING 
A WEAK MICROWAVE EYE FEATURE, WHICH SUPPORTS THE INITIAL POSITION 
WITH GOOD CONFIDENCE. THE INITIAL INTENSITY IS ASSESSED AT 40 KNOTS 
BASED ON THE HIGHER END OF DVORAK INTENSITY ESTIMATES RANGING FROM 
T2.0 TO T3.0 (30 TO 45 KNOTS). UPPER-LEVEL ANALYSIS INDICATES A 
FAVORABLE ENVIRONMENT WITH LOW VERTICAL WIND SHEAR (VWS) AND GOOD 
POLEWARD OUTFLOW. TS 30W IS TRACKING NORTHWESTWARD UNDER THE 
STEERING INFLUENCE OF THE DEEP SUBTROPICAL RIDGE (STR) TO THE 
NORTHEAST.
3. FORECAST REASONING.    
   A. THERE IS NO CHANGE TO THE FORECAST PHILOSOPHY SINCE THE 
PREVIOUS PROGNOSTIC REASONING MESSAGE.
   B. TS 30W WILL TRACK WEST-NORTHWESTWARD TO WESTWARD OVER THE NEXT 
36 HOURS ALONG THE SOUTHERN PERIPHERY OF THE STR. ENVIRONMENTAL 
CONDITIONS ARE FORECAST TO REMAIN FAVORABLE WITH A PERSISTENT 
POLEWARD OUTFLOW CHANNEL, ACCOMPANIED BY WARM SSTS. THIS WILL ALLOW 
THE SYSTEM TO INTENSIFY TO A PEAK INTENSITY OF 55 KNOTS BY TAU 24. 
NEAR TAU 48, THE SYSTEM WILL TRACK INTO SLIGHTLY COOLER WATERS AND 
ENCOUNTER INCREASING VWS AND UPPER-LEVEL CONVERGENT FLOW, WHICH WILL 
SERVE TO WEAKEN THE SYSTEM. SHORTLY THEREAFTER, TS 30W TRACK WILL 
BEGIN TO SLOW AS IT TRANSITIONS STEERING TO THE WESTERN STR AND 
BEGINS TO TRACK WEST-SOUTHWESTWARD TO SOUTHWESTWARD. 
   C. AFTER TAU 72, TS 30W WILL CONTINUE TRACKING SOUTHWESTWARD, 
MAKING LANDFALL ALONG THE COAST OF VIETNAM JUST AFTER TAU 96. THE 
SYSTEM WILL WEAKEN RAPIDLY AND IS FORECAST TO DISSIPATE BY TAU 120. 
DYNAMIC MODEL GUIDANCE SHOWS GENERALLY GOOD AGREEMENT THROUGH TAU 36 
BUT DIVERGES AFTER TAU 36 WITH A LARGE DEGREE OF UNCERTAINTY IN THE 
TIMING OF THE SOUTHWESTWARD TURN AND TRACK SPEEDS. COAMPS REMAINS 
THE ONLY TRACKER STILL SHOWING A NORTHWESTWARD TRACK TOWARD HAINAN 
ISLAND. DUE TO THE UNCERTAINTY IN THE MODEL GUIDANCE, THERE IS 
OVERALL LOW CONFIDENCE IN THE FORECAST TRACK.//
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