WDPN31 PGTW 311500 MSGID/GENADMIN/NAVMARFCSTCEN PEARL HARBOR HI/JTWC// SUBJ/PROGNOSTIC REASONING FOR TROPICAL STORM 12W (KROVANH)// WARNING NR 15// RMKS/ 1. FOR METEOROLOGISTS. 2. 12 HOUR SUMMARY AND ANALYSIS. A. TROPICAL STORM (TS) 12W (KROVANH) HAS BEGUN TO WEAKEN AS IT ENCOUNTERS INCREASING VERTICAL WIND SHEAR AHEAD OF AN APPROACHING BAROCLINIC SYSTEM. TS 12W HAS ALSO BEGUN ACCELERATING TO THE NORTH- NORTHEAST OVER THE PAST 12 HOURS AS IT HAS CRESTED THE RIDGE AXIS. THERE IS GOOD CONFIDENCE IN THE CURRENT POSITION AS THE SYSTEM REMAINS IN RADAR RANGE OF MAINLAND JAPAN. CURRENT INTENSITY IS BASED ON DVORAK SATELLITE INTENSITY ESTIMATES FROM PGTW AND RJTD. 3. FORECAST REASONING. A. THE FORECAST REASONING HAS NOT CHANGED SINCE THE LAST PROGNOSTIC REASONING BULLETIN. B. TS 12W WILL CONTINUE TO ACCELERATE TO THE NORTH-NORTHEAST THROUGH TAU 12 BEFORE TURNING MORE EASTWARD NEAR TAU 24. THE SYSTEM IS EXPECTED TO BEGIN EXTRATROPICAL TRANSITION NEAR TAU 12, AND TO BE FULLY EXTRATROPICAL BY TAU 36. THE AVAILABLE NUMERIC MODEL GUIDANCE SUPPORTS THIS SCENARIO WITH CAPTURE OF THE SYSTEM BY THE BAROCLINIC SYSTEM RANGING FROM TAU 18 TO TAU 30, WITH ALL AVAILABLE GUIDANCE INDICATING TRANSITION WILL BE COMPLETE BY TAU 36. FORECAST TEAM: DELTA.// NNNN