MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI// SUBJ/PROGNOSTIC REASONING FOR TROPICAL STORM 15W (KUJIRA) WARNING NR 007// RMKS/ 1. FOR METEOROLOGISTS. 2. 6 HOUR SUMMARY AND ANALYSIS. TROPICAL STORM (TS) 15W (KUJIRA), LOCATED APPROXIMATELY 232 NM NORTH OF MINAMI TORI SHIMA, HAS TRACKED NORTH-NORTHWESTWARD AT 16 KNOTS OVER THE PAST SIX HOURS. ANIMATED MULTISPECTRAL SATELLITE IMAGERY DEPICTS A PARTIALLY-EXPOSED, WELL-DEFINED LOW-LEVEL CIRCULATION CENTER (LLCC) WITH PERSISTENT DEEP CONVECTION OVER THE WESTERN SEMICIRCLE. A 280622Z SSMIS 37GHZ MICROWAVE IMAGE REVEALS SHALLOW BANDING WRAPPING TIGHTLY INTO A DEFINED LLCC, WHICH SUPPORTS THE INITIAL POSITION WITH GOOD CONFIDENCE. THE INITIAL INTENSITY IS ASSESSED AT 45 KNOTS BASED ON A PGTW DVORAK ESTIMATE OF T3.0 (45 KNOTS) AND RECENT ASCAT DATA. UPPER-LEVEL ANALYSIS INDICATES A MARGINALLY-FAVORABLE ENVIRONMENT WITH ROBUST POLEWARD OUTFLOW, WARM SST (29-30C) AND LOW VERTICAL WIND SHEAR (VWS). HOWEVER, STRONG CONVERGENCE OVER THE SOUTHERN SEMICIRCLE CONTINUES TO HINDER CONVECTIVE DEVELOPMENT. TS 15W IS TRACKING NORTH-NORTHWESTWARD UNDER THE STEERING INFLUENCE 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 NORTHWARD TO NORTH-NORTHEASTWARD THROUGH TAU 24 AS IT ROUNDS THE SUBTROPICAL RIDGE. AFTER TAU 24, TS 15W WILL TURN NORTHEASTWARD AND SHOULD BEGIN EXTRATROPICAL TRANSITION (ETT) NEAR TAU 36 AS IT INTERACTS WITH MIDLATITUDE WESTERLIES AND ENCOUNTERS INCREASING VWS (20-30 KNOTS). THE SYSTEM IS FORECAST TO INTENSIFY TO A PEAK INTENSITY OF 65 KNOTS BY TAU 36. GRADUAL WEAKENING IS EXPECTED AFTER TAU 36 AS VWS INCREASES TO 30-40 KNOTS AND THE SYSTEM TRACKS OVER COOL SST (24-20C). AS THE SYSTEM RECURVES EAST-NORTHEASTWARD TO EASTWARD, IT WILL COMPLETE ETT BETWEEN TAU 60 TO 72 AS IT GAINS FRONTAL CHARACTERISTICS AND BECOMES EMBEDDED WITHIN THE MIDLATITUDE WESTERLIES. NUMERICAL MODEL GUIDANCE AND THE ECMWF ENSEMBLE SOLUTIONS REMAIN IN TIGHT AGREEMENT THROUGHOUT THE FORECAST PERIOD. THUS, THERE IS HIGH CONFIDENCE IN THE JTWC FORECAST TRACK.// NNNN NNNN