WDPN31 PGTW 290300 MSGID/GENADMIN/NAVMARFCSTCEN PEARL HARBOR HI/JTWC// SUBJ/PROGNOSTIC REASONING FOR TROPICAL STORM 12W (KROVANH)// WARNING NR 05// RMKS/ 1. FOR METEOROLOGISTS. 2. 12-HOUR SUMMARY AND ANALYSIS. A. TROPICAL STORM (TS) 12W (KROVANH) HAS GRADUALLY INTENSIFIED AND TRACKED NORTH-NORTHWESTWARD ALONG THE SOUTHWESTERN PERIPHERY OF A MID-LEVEL SUBTROPICAL RIDGE TO THE NORTHEAST. ENVIRONMENTAL CONDITIONS HAVE BEEN FAVORABLE FOR DEVELOPMENT. ANIMATED WATER VAPOR SATELLITE IMAGERY SHOWS EXCELLENT RADIAL OUTFLOW OVER THE SYSTEM WITH A TROPICAL UPPER TROPOSPHERIC (TUTT) CELL TO THE WEST PROVIDING POLEWARD VENTILA- TION AND AN UPPER LEVEL RIDGE TO THE SOUTH ENHANCING EQUATORWARD OUTFLOW. ITS PROXIMITY TO RIDGE AXES HAS ALSO ACCOUNTED FOR THE LOW VERTICAL WIND SHEAR ALOFT. ADDITIONALLY, ALONG-TRACK TEMPERATURES ARE WELL IN EXCESS OF 28 DEGRESS CELSIUS. CURRENT POSITION AND INTENSITY ARE BASED ON ANIMATED MULTISPECTRAL IMAGERY AND ON DVORAK FIXES FROM PGTW, RJTD, AND KNES WITH A FAIR DEGREE OF CONFIDENCE. 3. FORECAST REASONING. A. THE INTENSITY FORECAST HAS NOT CHANGED BUT THE TRACK FORECAST HAS CHANGED SLIGHTLY SINCE THE PREVIOUS BULLETIN. THIS TRACK IS RIGHT OF THE PREVIOUS FORECAST AND RECURVES THE SYSTEM SOONER WITHOUT MAKING LANDFALL INTO CENTRAL JAPAN. B. TROPICAL STORM KROVANH IS EXPECTED TO CONTINUE TRACKING NORTHWESTWARD ALONG THE PERIPHERY OF THE STEERING RIDGE DESCRIBED IN PARA 2.A AND STEADILY INTENSIFY, PEAKING AT 65 KNOTS AT TAU 36. BY TAU 48, IT WILL BEGIN TO RECURVE TO THE NORTHEAST AS A MID-LEVEL TROUGH CURRENTLY OVER SOUTHERN MONGOLIA, DESCENDS INTO JAPAN AND CAUSES A BREAK/WEAKNESS IN THE STEERING RIDGE. BY TAU 72, TS 12W WILL COMMENCE ITS EXTRA-TROPICAL TRANSITION. C. AFTER TAU 72, TS 12W WILL ACCELERATE NORTHEASTWARD AND BECOME FULLY EXTRA-TROPICAL BY TAU 96. THE AVAILABLE NUMERIC GUIDANCE IS IN BETTER AGREEMENT ON THIS CYCLE. WITH THE EXCEPTION OF EGRR AND JGSM ON THE LEFT SIDE OF THE ENVELOPE, THE REMAINDER OF THE MODEL TRACKERS ARE IN TIGHT PACKING WITH CONSENSUS AND ECMWF ON THE LEFT EDGE OF THE PACKING. THIS TRACK FORECAST IS SLIGHTLY LEFT OF CONSENSUS. FORECAST TEAM: BRAVO.// NNNN