MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI// SUBJ/PROGNOSTIC REASONING FOR TROPICAL STORM 15W (KUJIRA) WARNING NR 005// RMKS/ 1. FOR METEOROLOGISTS. 2. 6 HOUR SUMMARY AND ANALYSIS. TROPICAL STORM (TS) 15W (KUJIRA), LOCATED APPROXIMATELY 94 NM NORTHEAST OF MINAMI TORI SHIMA, HAS TRACKED NORTHWESTWARD AT 20 KNOTS (KTS) OVER THE PAST SIX HOURS. ANIMATED ENHANCED INFRARED SATELLITE IMAGERY SHOWS A LOW LEVEL CIRCULATION CENTER (LLCC) OBSCURED BY FLARING DEEP CONVECTION EXTENDING OVER THE NORTHERN AND EASTERN SEMICIRCLES. A 271743Z SSMIS 91 GHZ MICROWAVE IMAGE SHOWS IMPROVED BANDING WRAPPING INTO THE LLCC FROM ALL QUADRANTS; THEREFORE, THERE IS GOOD CONFIDENCE IN THE INITIAL POSITION. THE INITIAL INTENSITY REMAINS ASSESSED AT 35 KTS BASED ON A 271740Z ADVANCED DVORAK TECHNIQUE ESTIMATE OF T2.5 (35 KTS) AND DVORAK CURRENT INTENSITY ESTIMATES OF T2.0-2.5 (30-35 KTS) BY PGTW AND RJTD. UPPER LEVEL ANALYSIS REVEALS AN IMPROVING ENVIRONMENT CHARACTERIZED BY INCREASING POLEWARD OUTFLOW AND ROBUST EQUATORWARD OUTFLOW BEING OFFSET BY A BROAD, CONVERGENT UPPER LOW LOCATED TO THE SOUTHWEST OF THE SYSTEM. WARM (29-30 CELSIUS) SEA SURFACE TEMPERATURES AND LOW (<10 KTS) VERTICAL WIND SHEAR (VWS) REMAIN CONDUCIVE FOR CONTINUED DEVELOPMENT, ESTABLISHING AN OVERALL MARGINALLY FAVORABLE ENVIRONMENT. TS 15W IS TRACKING NORTHWESTWARD ALONG THE PERIPHERY OF A SUBTROPICAL RIDGE (STR) POSITIONED TO THE NORTHEAST. 3. FORECAST REASONING. A. NO CHANGE TO THE FORECAST PHILOSOPHY SINCE THE PREVIOUS PROGNOSTIC REASONING MESSAGE. B. TS 15W IS FORECAST TO TRACK NORTH-NORTHWESTWARD THROUGH TAU 12 WITH STEADY INTENSIFICATION. AFTER TAU 12, TS 15W WILL BEGIN TO ROUND THE STR WITH FURTHER INTENSIFICATION DUE TO IMPROVING POLEWARD OUTFLOW ASSOCIATED WITH A MAJOR SHORTWAVE TROUGH DIGGING SOUTH OF JAPAN. THE SYSTEM IS EXPECTED TO PEAK AT 65 KNOTS BY TAU 36. EXTRATROPICAL TRANSITION (ETT) IS EXPECTED TO BEGIN AROUND TAU 48, IF NOT SOONER, AS TS 15W RECURVES INTO THE MIDLATITUDE WESTERLIES. FOLLOWING THIS, TS 15W WILL STEADILY WEAKEN AS IT ENCOUNTERS INCREASING VWS (25-30 KTS) AND TRACKS OVER COOL SST VALUES (20-23 CELSIUS). THE SYSTEM IS EXPECTED TO COMPLETE ETT NEAR TAU 72 AS IT GAINS FRONTAL CHARACTERISTICS AND BECOMES EMBEDDED WITHIN THE MIDLATITUDE WESTERLIES. NUMERICAL MODEL GUIDANCE AND THE 27/12Z ECMWF ENSEMBLE SOLUTIONS REMAIN IN TIGHT AGREEMENT THROUGHOUT THE FORECAST PERIOD, LENDING HIGH CONFIDENCE TO THE JTWC FORECAST TRACK.// NNNN NNNN