WDPN31 PGTW 300300 MSGID/GENADMIN/NAVMARFCSTCEN PEARL HARBOR HI/JTWC// SUBJ/PROGNOSTIC REASONING FOR TROPICAL STORM 12W (KROVANH)// WARNING NR 09// RMKS/ 1. FOR METEOROLOGISTS. 2. 12-HOUR SUMMARY AND ANALYSIS. A. TROPICAL STORM (TS) 12W (KROVANH) HAS INTENSIFIED SLIGHTLY AND MOVED ON A MORE WEST-NORTHWESTWARD DIRECTION ALONG THE SOUTH- WESTERN PERIPHERY OF A MID-LEVEL SUBTROPICAL RIDGE (STR) TO THE NORTHEAST. ANIMATED WATER VAPOR IMAGERY SHOWS THE NORTHERN FLANK OF THE STORM IS NOW ENCOUNTERING STRONG WESTERLIES ASSOCIATED WITH THE SUBTROPICAL JET STREAM. THIS, IN THE INTERIM, IS PROVIDING POLEWARD VENTILATION TO THE SYSTEM. THE UPPER-LEVEL ENVIRONMENT, FOR NOW, REMAINS FAVORABLE AS THE SYSTEM TRACKS UNDER A RIDGE AXIS IN A ZONE OF LOW TO MODERATE VERTICAL WIND SHEAR. ADDITIONALLY, THE SEA SURFACE TEMPERATURES ALONG ITS TRACK ARE WELL IN EXCESS OF 28 DEGREES CELSIUS. THE CURRENT INTENSITY AND POSITION ARE BASED ON DVORAK FIXES FROM PGTW, RJTD, AND KNES WITH A FAIR DEGREE OF CONFIDENCE. 3. FORECAST REASONING. A. THERE IS NO SIGNIFICANT CHANGE TO THE FORECAST PHILOSOPHY SINCE THE LAST BULLETIN. B. TS KROVANH IS EXPECTED TO CONTINUE TRACKING NORTHWESTWARD UP TO TAU 12 BEFORE IT RECURVES TO THE NORTHEAST AND BEGINS ITS RAPID EXTRATROPICAL TRANSITION. THE SYSTEM WILL THEN GRADUALLY WEAKEN AFTER RECURVATURE. THE FAVORABLE CONDITIONS DESCRIBED IN PARA 2.A WILL RAPIDLY DIMINISH AS THE SYSTEM GETS EMBEDDED IN THE BAROCLINIC ZONE. THE AVAILABLE NUMERIC GUIDANCE IS IN GOOD AGREEMENT WITH CONSENSUS JUST TO THE RIGHT OF THIS TRACK FORECAST. GFS HAS EMERGED AS THE EXTREME LEFT OUTLIER. WORTH MENTIONING IS THAT JGSM, ECMWF, AND GFS ARE JUST LEFT OF THIS FORECAST AND BRING THE SYSTEM TO A LANDFALL IN CENTRAL JAPAN. FORECAST TEAM: BRAVO.// NNNN