WDPN32 PGTW 040300 MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI// SUBJ/PROGNOSTIC REASONING FOR TROPICAL STORM 23W (CHOI-WAN) WARNING NR 07// RMKS// 1. FOR METEOROLOGISTS. 2. 6 HOUR SUMMARY AND ANALYSIS. TROPICAL STORM (TS) 23W (CHOI-WAN), LOCATED APPROXIMATELY 343 NM WEST OF WAKE ISLAND, HAS TRACKED WEST-NORTHWESTWARD AT 18 KNOTS OVER THE PAST SIX HOURS. RECENT ANIMATED MULTISPECTRAL SATELLITE IMAGERY (MSI) DEPICTS THE SYSTEM HAS CONSOLIDATED AS INCREASED DEEP CONVECTION WITH FORMATIVE BANDS TIGHTLY WRAP INTO THE CENTROID. A 032326Z METOP-B MICROWAVE IMAGE SHOWS THE BULK OF THE DEEP CONVECTION REMAINS OVER THE NORTHEAST AND SOUTHWEST QUADRANTS. THE CURRENT POSITION IS BASED ON THE MSI, AFOREMENTIONED METOP-B IMAGE, AND SATELLITE FIXES FROM PGTW AND RJTD WITH FAIR CONFIDENCE. ALTHOUGH TS 23W IS STILL A VERY LARGE SYSTEM, IT IS GAINING CHARACTERISTICS TYPICAL OF A TROPICAL STORM, I.E., MORE CENTRALIZED DEEP CONVECTION AND A CONTRACTING WIND FIELD. THE INITIAL INTENSITY HAS RISEN TO 50 KNOTS BASED ON THE IMPROVING STRUCTURE. UPPER-LEVEL ANALYSIS INDICATES A FAVORABLE ENVIRONMENT WITH GOOD OUTFLOW AND LOW VWS. ADDITIONALLY, WARM SSTS ARE CONDUCIVE FOR DEVELOPMENT. TS 23W IS TRACKING ALONG THE SOUTHERN PERIPHERY OF THE STR TO THE NORTH. 3. FORECAST REASONING. A. NO CHANGE TO FORECAST PHILOSOPHY SINCE THE PREVIOUS PROGNOSTIC REASONING MESSAGE. B. TS 23W WILL CONTINUE TRACKING WESTWARD UNDER THE INFLUENCE OF THE STR. FAVORABLE ENVIRONMENTAL CONDITIONS WILL PERSIST; HOWEVER, DUE TO THE BROAD NATURE OF LLCC, TS 23W IS EXPECTED TO GRADUALLY INTENSIFY, LEADING TO A PEAK INTENSITY OF 85 KNOTS BY TAU 48. CONCURRENTLY, CHOI-WAN IS FORECAST TO ROUND THE STR AND TRACK MORE POLEWARD. AS IT GAINS LATITUDE, INCREASING VWS AND DECREASING SSTS WILL BEGIN TO WEAKEN THE SYSTEM. C. BEYOND TAU 72, STRONG VWS IS EXPECTED TO HAMPER TS 23W AS IT ACCELERATES POLEWARD. BY TAU 96, CHOI-WAN IS FORECAST TO COMMENCE EXTRA-TROPICAL TRANSITION AS IT ENTERS THE COLD BAROCLINIC ZONE. THE CYCLONE WILL TRANSFORM INTO A COLD CORE LOW BY TAU 120. AVAILABLE MODEL GUIDANCE IS IN GOOD AGREEMENT, HOWEVER, GIVEN THE UNCERTAINTY IN THE CURRENT STORM MOTION AND THE INITIAL PORTION OF THE FORECAST TRACK, THERE IS LOW CONFIDENCE IN THE JTWC FORECAST TRACK.// NNNN