MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI// SUBJ/PROGNOSTIC REASONING FOR TROPICAL STORM 17W (KAMMURI) WARNING NR 18// RMKS/ 1. FOR METEOROLOGISTS. TROPICAL STORM (TS) 17W (KAMMURI), LOCATED APPROXIMATELY 337 NM SOUTHEAST OF NARITA AIRPORT, HAS TRACKED NORTHEASTWARD AT 13 KNOTS OVER THE PAST SIX HOURS. ANIMATED ENHANCED INFRARED SATELLITE (EIR) IMAGERY DEPICTS A WRAPPED, SLIGHTLY EXPOSED LOW-LEVEL CIRCULATION CENTER (LLCC) WITH SOME DEEP CONVECTION SHEARED OVER THE NORTHERN SEMI-CIRCLE. A 281639Z AMSU-B IMAGE REVEALS SOME MODERATE CONVECTION TO THE SOUTH AND NORTHEAST OF THE LLCC. THE INITIAL POSITION IS BASED ON THIS IMAGE AND THE EIR IMAGERY. THE INITIAL INTENSITY IS ASSESSED AT 45 KNOTS BASED ON PERSISTENCE FROM A 281105Z ASCAT IMAGE AS THE DVORAK ESTIMATES ARE NOT REPRESENTATIVE AS THIS SYSTEM BECOMES EXTRA-TROPICAL. UPPER-LEVEL ANALYSIS INDICATES A MARGINAL ENVIRONMENT CHARACTERIZED BY MODERATE (15 TO 30 KNOTS) WESTERLY VERTICAL WIND SHEAR. TS 17W IS TRACKING ALONG THE NORTHWESTERN PERIPHERY OF THE SUBTROPICAL RIDGE (STR) WITHIN MIDLATITUDE WESTERLY FLOW. 3. FORECAST REASONING. A. NO CHANGE TO THE FORECAST PHILOSOPHY SINCE THE PREVIOUS PROGNOSTIC REASONING MESSAGE. B. TS 17W CONTINUES TO UNDERGO EXTRA-TROPICAL TRANSITION (ETT) AND IS INTERACTING WITH THE MIDLATITUDE WESTERLIES AND THE FRONTAL ZONE, LOCATED JUST TO THE NORTH OF THE SYSTEM. KAMMURI IS WELL NORTH OF THE STR AXIS AND CONTINUES TO ACCELERATE NORTHEASTWARD AND WILL WEAKEN SLIGHTLY AS IT BECOMES FULLY EMBEDDED WITHIN THE MIDLATITUDE WESTERLIES. TS 17W WILL COMPLETE ETT BY TAU 24 AS IT GAINS FRONTAL CHARACTERISTICS BUT IS FORECAST TO REMAIN A STRONG COLD-CORE LOW. DYNAMIC MODEL GUIDANCE IS IN VERY TIGHT AGREEMENT, AND, AS SUCH, THERE IS HIGH CONFIDENCE IN THE JTWC TRACK.// NNNN NNNN