MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI// SUBJ/PROGNOSTIC REASONING FOR TROPICAL STORM 23W (MATMO) WARNING NR 003// RMKS/ 1. FOR METEOROLOGISTS. 2. 6 HOUR SUMMARY AND ANALYSIS. TROPICAL STORM (TS) 23W (MATMO), LOCATED APPROXIMATELY 230 NM SOUTHEAST OF DA NANG, VIETNAM, HAS TRACKED WEST-NORTHWESTWARD AT 09 KNOTS OVER THE PAST SIX HOURS. ANIMATED ENHANCED INFRARED SATELLITE IMAGERY AND A 300605Z AMSR2 89GHZ IMAGE DEPICT IMPROVED DEEP CONVECTIVE BANDING OVER THE WESTERN SEMICIRCLE WRAPPING INTO A DEFINED LOW-LEVEL CIRCULATION CENTER (LLCC), WHICH SUPPORTS THE CURRENT POSITION WITH GOOD CONFIDENCE. A 300210Z ASCAT-A IMAGE SHOWS EXTENSIVE 35-40 KNOT WINDS OVER THE WESTERN SEMICIRCLE, WHICH SUPPORTS THE CURRENT INTENSITY ASSESSMENT OF 40 KNOTS. DVORAK INTENSITY ESTIMATES RANGING FROM T2.5-3.0 (35-45 KNOTS) ALSO SUPPORT THE INTENSITY ASSESSMENT. UPPER-LEVEL ANALYSIS REVEALS A FAVORABLE ENVIRONMENT WITH ROBUST POLEWARD OUTFLOW OFFSET SLIGHTLY BY LOW (10- 15 KNOTS) EASTERLY VERTICAL WIND SHEAR. SST VALUES OF 28-29C ARE CONDUCIVE FIR FURTHER DEVELOPMENT. TS 23W IS TRACKING ALONG THE SOUTHERN PERIPHERY OF A SUBTROPICAL RIDGE (STR) POSITIONED TO THE NORTH. 3. FORECAST REASONING. A. THERE IS NO SIGNIFICANT CHANGE TO THE FORECAST PHILOSOPHY FROM THE PREVIOUS PROGNOSTIC REASONING MESSAGE. B. TS MATMO WILL CONTINUE ON ITS CURRENT TRACK UNDER THE STR, MAKING LANDFALL BY TAU 12 ALONG THE EAST COAST OF VIETNAM. NUMERICAL MODEL GUIDANCE IS IN TIGHT AGREEMENT THROUGH THE FORECAST PERIOD, LENDING HIGH CONFIDENCE TO THE JTWC TRACK FORECAST. SLIGHT INTENSIFICATION IS LIKELY PRIOR TO LANDFALL WITH A PEAK INTENSITY NEAR 45 KNOTS EXPECTED WITHIN THE NEXT NINE HOURS. AFTER LANDFALL, RAPID WEAKENING IS ANTICIPATED AS THE SYSTEM TRACKS OVER THE MOUNTAINOUS TERRAIN OF VIETNAM.// NNNN NNNN