MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI// SUBJ/PROGNOSTIC REASONING FOR TROPICAL STORM 04W (MERBOK) WARNING NR 07// RMKS// 1. FOR METEOROLOGISTS. 2. 6 HOUR SUMMARY AND ANALYSIS. TROPICAL STORM 04W (MERBOK), LOCATED APPROXIMATELY 21 NM SOUTHEAST OF HONG KONG, HAS TRACKED NORTHWARD AT 09 KNOTS OVER THE PAST SIX HOURS. ANIMATED INFRARED (IR) SATELLITE IMAGERY SHOWS FLARING CONVECTION LOCATED TO THE SOUTH OF THE LOW LEVEL CIRCULATION CENTER (LLCC). THE CONVECTION IS DISPLACED DUE TO INCREASING VERTICAL WIND SHEAR IMPACTING THE SYSTEM. THE INITIAL POSITION IS BASED ON ANIMATED IR IMAGERY AND A 121038Z F17 SSMIS 37GHZ MICROWAVE IMAGE THAT SHOWS A DISORGANIZED LOWER LEVEL CONVECTIVE STRUCTURE AS THE SYSTEM BEGINS TO INTERACT WITH LAND. THE INITIAL INTENSITY OF 45 KNOTS IS BASED ON MULTIAGENCY DVORAK ESTIMATES OF T3.0 AND A SATCON ESTIMATE OF 45 KNOTS. ENVIRONMENTAL ANALYSIS SHOWS DETERIORATING UPPER LEVEL CONDITIONS AS TS 04W IS NOW IN AN AREA OF MODERATE TO UNFAVORABLE VERTICAL WIND SHEAR (20-25 KNOTS) AND THE EQUATORWARD OUTFLOW CHANNEL HAS BECOME LESS ORGANIZED. TS MERBOK IS CURRENTLY TRACKING NORTHWEST HOWEVER, THE TRACK IS TURNING TO THE EAST DUE TO THE SYSTEM ROUNDING THE NORTHWEST PERIPHERY OF A SUBTROPICAL STEERING RIDGE (STR). 3. FORECAST REASONING. A. NO SIGNIFICANT CHANGE TO THE FORECAST PHILOSOPHY SINCE THE PREVIOUS PROGNOSTIC REASONING MESSAGE. B. TS 04W IS FORECAST TO MAKE LANDFALL BEFORE TAU 12 TO THE EAST OF HONG KONG. ONCE THE SYSTEM MAKES LANDFALL IT WILL RECURVE TO THE NORTHEAST AS IT CONTINUES TO ROUND THE NORTHWESTERN PERIPHERY OF THE STR. THE SYSTEMS CURRENT PROXIMITY TO LAND WILL PREVENT FURTHER INTENSIFICATION PRIOR TO LANDFALL. THE RUGGED TERRAIN OF SOUTHEAST CHINA WILL RAPIDLY DETERIORATE THE SYSTEM POST LANDFALL RESULTING IN COMPLETE DISSIPATION BY TAU 36. AFTER TAU 36 THE REMNANTS OF TS MERBOK WILL MOVE INTO THE EAST CHINA SEA WITH A LIMITED POSSIBILITY OF RE-INTENSIFICATION. THE DYNAMIC MODEL GUIDANCE REMAINS IN STRONG AGREEMENT LENDING HIGH CONFIDENCE IN THE JTWC TRACK FORECAST.// NNNN NNNN