WDPN31 PGTW 221500 MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI// SUBJ/PROGNOSTIC REASONING FOR TROPICAL STORM 03W WARNING NR 06// RMKS// 1. FOR METEOROLOGISTS. 2. 6 HOUR SUMMARY AND ANALYSIS. TROPICAL STORM (TS) 03W (SANVU), LOCATED APPROXIMATELY 605 NM SOUTH OF IWO TO, JAPAN, HAS TRACKED NORTHWESTWARD AT 12 KNOTS OVER THE PAST SIX HOURS. ANIMATED INFRARED SATELLITE IMAGERY SHOWS THE SYSTEM HAS FURTHER CONSOLIDATED AND CONVECTION HAS RESURGED, ESPECIALLY ALONG THE NORTHEAST FLANK. THE INITIAL POSITION WAS BASED ON THE ABOVE ANIMATION AND EXTRAPOLATED FROM A 220804Z SSMIS MICROWAVE IMAGE. THE INITIAL INTENSITY WAS BASED ON THE HIGH END OF DVORAK ESTIMATES FROM PGTW, KNES, AND RJTD. UPPER LEVEL ANALYSIS INDICATES A TROPICAL UPPER TROPOSPHERIC TROUGH (TUTT) TO THE WEST AND NORTHEAST OF TS 03W ARE CAUSING MODERATE POLEWARD OUTFLOW. HOWEVER, THERE IS NO SIGNIFICANT OUTFLOW EQUATORWARD OF THE SYSTEM. THESE ARE EVIDENT ON ANIMATED WATER VAPOR SATELLITE IMAGERY. TS 03W IS TRACKING ALONG THE SOUTHWESTERN PERIPHERY OF THE SUBTROPICAL RIDGE (STR) EXTENSION TO THE NORTHEAST. LIGHT VERTICAL WIND SHEAR (VWS) AT 05-10 KNOTS AND WARM SEA SURFACE TEMPERATURE (SST) AT 29-30 DEGREES CELSIUS ARE ALSO CONTRIBUTING TO THE CYCLONE'S CONTINUED DEVELOPMENT. 3. FORECAST REASONING. A. THE FORECAST PHILOSOPHY HAS NOT CHANGED SINCE THE PREVIOUS PROGNOSTIC REASONING BULLETIN. B. TS 03W IS EXPECTED TO ROUND THE WESTERN EDGE OF THE STEERING STR OVER THE NEXT 72 HOURS, GRADUALLY INTENSIFY AND PEAK AT 75 KNOTS BY TAU 48 BEFORE RECURVING NORTHEASTWARD. THE INITIAL EXPOSURE TO THE STRONG WESTERLIES ASSOCIATED WITH THE SUBTROPICAL JET STREAM WILL PROVIDE EXCELLENT OUTFLOW PRIOR TO RECURVATURE. THIS, IN ADDITION TO THE LIGHT VWS AND WARM SST, WILL FUEL THE INTENSIFICATION. C. BY TAU 72, TS SANVU 03W IS FORECAST TO ACCELERATE NORTHEASTWARD AND COMMENCE EXTRA-TROPICAL TRANSITION (ETT). INCREASING VWS AND COOLING SST WILL RAPIDLY ERODE AND WEAKEN THE SYSTEM. BY TAU 120, TS 03W WILL HAVE BECOME FULLY EMBEDDED IN THE BAROCLINIC ZONE AND COMPLETED ETT. THE AVAILABLE NUMERICAL GUIDANCE IS IN A TIGHTER ENVELOPE WITH NO SIGNIFICANT OUTLIERS. THIS TRACK FORECAST IS VERY CLOSE TO MODEL CONSENSUS (CONW) EXCEPT DURING THE EXTENDED TAUS WHERE IT IS SLIGHTLY FASTER THAN CONW TO ACCOUNT FOR KNOWN MODEL TENDENCIES DURING ETT. // NNNN