WDPN31 PGTW 170300 MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI// SUBJ/PROGNOSTIC REASONING FOR TROPICAL STORM 20W (TALIM) WARNING NR 34// RMKS// 1. FOR METEOROLOGISTS. 2. 6 HOUR SUMMARY AND ANALYSIS. TROPICAL STORM 20W (TALIM), LOCATED APPROXIMATELY 120 NM SOUTH OF SASEBO, JAPAN, HAS TRACKED NORTHEASTWARD AT 14 KNOTS OVER THE PAST SIX HOURS. ANIMATED ENHANCED MULTISPECTRAL SATELLITE IMAGERY DEPICTS DEEPENING CONVECTION IN THE NORTHWESTERN QUADRANT THAT IS PARTIALLY OBSCURING A LOW LEVEL CIRCULATION CENTER (LLCC). THE NORTHERN PORTION OF THE SYSTEM IS NOW OVER SOUTHERN JAPAN. THE INITIAL POSITION IS PLACED WITH HIGH CONFIDENCE BASED ON THE PARTIALLY EXPOSED LLCC IN THE MULTI-SPECTRAL LOOP AND A LOW REFLECTIVITY AREA VISIBLE IN ANIMATED RADAR IMAGERY FROM JMA. THE INITIAL INTENSITY OF 55 KNOTS IS HEDGED ON THE LOWER END OF MULTI AGENCY DVORAK CURRENT INTENSITY ESTIMATES RANGING FROM T3.5 TO T4.0 (55-65 KNOTS) FROM PGTW AND RJTD RESPECTIVELY, AND IS SUPPORTED BY A SATCON ESTIMATE OF 52 KNOTS. ENVIRONMENTAL ANALYSIS SHOWS THAT THE STRONG POLEWARD OUTFLOW CHANNEL, ENHANCED BY THE MID-LATITUDE JET, AND HIGH SEA SURFACE TEMPERATURES, ARE BEING OFFSET BY POOR EQUATORWARD OUTFLOW AND HIGH(25-30 KNOTS) VERTICAL WIND SHEAR. TS TALIM IS CONTINUING TO ACCELERATE NORTHEAST ALONG THE NORTHWESTERN PERIPHERY OF A DEEP- LAYERED SUBTROPICAL RIDGE (STR) TO THE SOUTHEAST. 3. FORECAST REASONING. A. THERE IS NO SIGNIFICANT CHANGE TO THE FORECAST PHILOSOPHY FROM THE PREVIOUS PROGNOSTIC REASONING MESSAGE. B. TS 20W WILL TRACK TO THE NORTHEAST AND GRADUALLY ACCELERATE FOR THE DURATION OF THE FORECAST. THE SUBTROPICAL RIDGE WILL REMAIN THE PRIMARY STEERING FEATURE. THE SYSTEM WILL MAKE LANDFALL WITHIN THE NEXT THREE HOURS TO THE SOUTH OF SASEBO, AS THE NORTHERN PORTIONS OF THE SYSTEM ARE ALREADY OVER SOUTHERN JAPAN. OVER THE NEXT 12 HOURS, THE SYSTEM WILL TRACK ACROSS KYUSHU, THEN SOUTHERN HONSHU, AND EXIT INTO THE SEA OF JAPAN SHORTLY AFTER TAU 12. SLIGHT WEAKENING WILL OCCUR AS TS 20W INTERACTS WITH THE TERRAIN OF SOUTHERN JAPAN. COOL SEA SURFACE TEMPERATURES AND HIGH VERTICAL WIND SHEAR WILL PREVENT RE-INTENSIFICATION AS THE SYSTEM TRACKS THROUGH THE SEA OF JAPAN. INCREASED INTERACTION WITH A MID-LATITUDE TROUGH WILL CAUSE THE SYSTEM TO BEGIN EXTRATROPICAL TRANSITION BY TAU 24. TS 20W IS FORECAST TO COMPLETE EXTRATROPICAL TRANSITION BY TAU 48 AS IT BECOMES IMBEDDED IN THE MID-LATITUDE TROUGH. TS TALIM WILL MAKE A SECONDARY LANDFALL OVER SOUTHERN HOKKAIDO BEFORE EXITING OUT INTO THE SEA OF OKHOSTK AS A COLD CORE LOW WITH A LARGE GALE FORCE WIND FIELD TRACKS TO THE NORTHEAST. DYNAMIC MODEL GUIDANCE REMAINS IN TIGHT AGREEMENT WITH ONLY A MINOR SHIFT TO THE EAST IN THE TRACK LENDING HIGH CONFIDENCE IN THE JTWC TRACK FORECAST.// NNNN