MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI// SUBJ/PROGNOSTIC REASONING FOR TROPICAL STORM 16W (FUNG-WONG) WARNING NR 21// RMKS// 1. FOR METEOROLOGISTS. 2. 6 HOUR SUMMARY AND ANALYSIS. TROPICAL STORM (TS) 16W (FUNG-WONG), LOCATED APPROXIMATELY 135 NM SOUTH-SOUTHEAST OF SHANGHAI, CHINA, HAS TRACKED NORTHWARD AT 10 KNOTS OVER THE PAST SIX HOURS. ANIMATED ENHANCED INFRARED (EIR) SATELLITE IMAGERY DEPICTS THE DEEP CONVECTION HAS WEAKENED AND SHEARED TO THE NORTHEAST. A 221138Z SSMIS MICROWAVE IMAGE REVEALS TIGHTLY-CURVED BANDING OVER THE EASTERN SEMI-CIRCLE WRAPPING INTO A WELL-DEFINED CENTER. THE CURRENT POSITION IS BASED ON EIR ANIMATION AND AFOREMENTIONED MICROWAVE IMAGE WITH GOOD CONFIDENCE. THE INITIAL INTENSITY OF 40 KNOTS IS BASED ON AN OVERALL ASSESSMENT OF DVORAK CURRENT INTENSITY ESTIMATES FROM ALL REPORTING AGENCIES AND WEAKENING TREND. UPPER-LEVEL ANALYSIS INDICATES TS 16W IS LOCATED IN AN AREA OF STRONG (25 TO 30 KNOT) WESTERLY VERTICAL WIND SHEAR (VWS). HOWEVER, THE SAME STRONG WINDS ASSOCIATED WITH THE PREVAILING WESTERLIES IS PROVIDING POLEWARD VENTILATION TO THE WEAKENING CONVECTION. TS 16W IS TRACKING ALONG THE NORTHWESTERN PERIPHERY OF A SUBTROPICAL RIDGE (STR) TO THE EAST. 3. FORECAST REASONING. A. NO CHANGE TO THE FORECAST PHILOSOPHY SINCE THE PREVIOUS PROGNOSTIC REASONING MESSAGE. B. TS FUNG-WONG WILL CONTINUE TRACKING NORTH-NORTHEASTWARD UNDER THE STEERING INFLUENCE OF THE STR. INCREASING VWS WILL GRADUALLY ERODE AND EVENTUALLY DISSIPATE THE SYSTEM BY TAU 36. CONCURRENTLY, TS 16W UNDERGOES EXTRA-TROPICAL TRANSITION AND WILL BECOME A WEAK COLD-CORE LOW BY END OF THE FORECAST PERIOD. AVAILABLE MODEL GUIDANCE IS OVERALL IN GOOD AGREEMENT, LENDING HIGH CONFIDENCE IN THE JTWC FORECAST.// NNNN NNNN