WDPN31 PGTW 230300 MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI// SUBJ/PROGNOSTIC REASONING FOR TROPICAL STORM 03W (SANVU) WARNING NR 08// RMKS// 1. FOR METEOROLOGISTS. 2. 6 HOUR SUMMARY AND ANALYSIS. TROPICAL STORM (TS) 03W (SANVU), LOCATED APPROXIMATELY 495 NM SOUTH OF IWO TO, JAPAN, HAS TRACKED NORTHWESTWARD AT 11 KNOTS OVER THE PAST SIX HOURS. ANIMATED MULTISPECTRAL SATELLITE IMAGERY (MSI) REVEALS TS 03W HAS MAINTAINED ITS TIGHTLY CURVED BANDING, WITH THE DEEPEST CONVECTION CONCENTRATED IN THE EASTERN SEMI-CIRCLE, WHILE CONVECTION IS LARGELY SUPPRESSED TO THE WEST OF THE LOW LEVEL CIRCULATION CENTER (LLCC). RECENT MICROWAVE IMAGERY SUGGESTS A SLIGHT INCREASE IN OVERALL INTENSITY OVER THE PAST SIX HOURS. A 222040Z SSMIS IMAGE DEPICTS MULTIPLE CONVECTIVE BANDING FEATURES WRAPPING INTO THE LLCC FROM THE NORTH AND EAST. THE CURRENT POSITION IS BASED ON THE ABOVE MSI AND SSMIS IMAGERY WITH FAIR CONFIDENCE. THE CURRENT INTENSITY IS ASSESSED AT 50 KNOTS BASED ON DVORAK ESTIMATES RANGING FROM 35 TO 55 KNOTS FROM RJTD, PGTW, AND KNES. UPPER LEVEL ANALYSIS INDICATES A POINT SOURCE OVER TS 03W, WITH VERTICAL WIND SHEAR (VWS) REMAINING LIGHT AT ABOUT 10 KNOTS. ANIMATED WATER VAPOR IMAGERY SUGGESTS THAT OUTFLOW HAS BECOME MARGINALLY BETTER OVER THE PAST SIX HOURS; HOWEVER THE SYSTEM IS STILL NOT FULLY INTERACTING WITH THE APPROACHING MID-LATITUDE TROUGH. SEA SURFACE TEMPERATURE (SST) REMAINS FAVORABLE AT 29-30 DEGREES CELSIUS. TS 03W IS TRACKING ALONG THE SOUTHWESTERN PERIPHERY OF THE SUBTROPICAL RIDGE (STR) TO THE NORTHEAST. 3. FORECAST REASONING. A. THE FORECAST PHILOSOPHY HAS NOT CHANGED SINCE THE PREVIOUS PROGNOSTIC REASONING BULLETIN. B. TS 03W IS EXPECTED TO GRADUALLY INTENSIFY AS IT ROUNDS THE WESTERN EDGE OF THE STEERING STR OVER THE NEXT 36-48 HOURS, BEFORE RECURVING NORTHEASTWARD. THE PEAK FORECAST INTENSITY PRIOR TO RECURVATURE IS 75 KNOTS. 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. AFTER TAU 48, THE VWS WILL BEGIN TO INCREASE AND THE SST WILL DECREASE, BEGINNING THE DISSIPATION OF TS 03W. C. BY TAU 72, TS 03W IS FORECAST TO ACCELERATE NORTHEASTWARD AND COMMENCE EXTRA-TROPICAL TRANSITION (ETT). INCREASING VWS AND RAPIDLY COOLING SST NORTH OF 24 DEGREES NORTH WILL WEAKEN THE SYSTEM RAPIDLY. BY TAU 96, TS 03W WILL HAVE BECOME FULLY EMBEDDED IN THE BAROCLINIC ZONE AND COMPLETED ETT. ALTHOUGH THERE ARE SOME DIFFERENCES IN THE EXACT SPEED OF FORWARD MOTION AFTER RECURVATURE, THE AVAILABLE NUMERICAL GUIDANCE REMAINS TIGHTLY PACKED, WITH NO SIGNIFICANT OUTLIERS. ADDITIONALLY, THE SINGLE MODEL ENSEMBLE PRODUCTS ALSO SHOW VERY LITTLE SPREAD AMONG THE MEMBERS. THIS TRACK FORECAST IS VERY CLOSE TO MODEL CONSENSUS (CONW) AND THE PREVIOUS FORECAST.// NNNN