MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI// SUBJ/PROGNOSTIC REASONING FOR TROPICAL STORM 04W (MERBOK) WARNING NR 06// RMKS// 1. FOR METEOROLOGISTS. 2. 6 HOUR SUMMARY AND ANALYSIS. TROPICAL STORM 04W (MERBOK), LOCATED APPROXIMATELY 72 NM SOUTH- SOUTHEAST OF HONG KONG, HAS TRACKED NORTH-NORTHWESTWARD AT 08 KNOTS OVER THE PAST SIX HOURS. ANIMATED MULTISPECTRAL SATELLITE IMAGERY (MSI) SHOWS PERSISTENT CONVECTION LOCATED TO THE SOUTHEAST OF THE LOW LEVEL CIRCULATION CENTER (LLCC), THE RESULT OF INCREASING VERTICAL WIND SHEAR. THE INITIAL POSITION IS BASED ON ANIMATED MSI AND A 120228Z METOP-A AMSU 89GHZ MICROWAVE IMAGE. THE INITIAL INTENSITY ESTIMATE OF 45 KNOTS IS HEDGED ON THE UPPER END OF SATCON AND MULTIAGENCY DVORAK ESTIMATES RANGING FROM T2.5 TO T3.0 AND A 120229Z METOP-A ASCAT IMAGE SHOWING A LARGE 40 KNOT WIND FIELD IN THE EASTERN SEMI CIRCLE. THOUGH SEA SURFACE TEMPERATURES REMAIN VERY WARM (30-31 C) ALONG THE FORECAST TRACK, UPPER LEVEL CONDITIONS ARE DETERIORATING WITH VERTICAL WIND SHEAR VALUES INCREASING (20-25 KNOTS) AND A LESS ORGANIZED EQUATORWARD OUTFLOW CHANNEL. TS 04W IS CURRENTLY TRACKING AROUND 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 MERBOK IS FORECAST TO MAKE LANDFALL BEFORE TAU 12 TO THE EAST OF HONG KONG AND BEGIN RECURVING TO THE NORTHEAST AS IT ROUNDS THE NORTHWESTERN PERIPHERY OF THE STR. THE DETERIORATING UPPER LEVEL CONDITIONS AND THE SYSTEMS PROXIMITY TO LAND WILL PREVENT FURTHER INTENSIFICATION. ONCE THE SYSTEM MAKES LANDFALL, INTERACTION WITH THE RUGGED TERRAIN WILL RAPIDLY DISSIPATE THE SYSTEM LEADING TO COMPLETE DISSIPATION BY TAU 36. THE REMNANTS OF TS 04W WILL EXIT INTO THE EAST CHINA SEA WITH A LIMITED OPPORTUNITY FOR RE- INTENSIFICATION. THE DYNAMIC MODEL GUIDANCE REMAINS IN TIGHT AGREEMENT LENDING HIGH CONFIDENCE IN THE JTWC TRACK FORECAST.// NNNN NNNN