WDPN31 PGTW 041500 MSGID/GENADMIN/NAVMARFCSTCEN PEARL HARBOR HI/JTWC// SUBJ/PROGNOSTIC REASONING FOR TROPICAL DEPRESSION 08W WARNING NR 08// RMKS/ 1. FOR METEOROLOGISTS. 2. 12 HOUR SUMMARY AND ANALYSIS. A. TROPICAL STORM (TS) 08W (GONI) HAS TURNED MORE NORTHWESTWARD OVER THE LAST 12 HOURS AS A MIDLATITUDE TROUGH HAS WEAKENED THE SUB- TROPICAL RIDGE (STR) OVER SOUTHERN CHINA. THE SYSTEM HAS ALSO SLOWLY INTENSIFIED OVER THE LAST 12 HOURS DESPITE 15 TO 20 KTS OF VERTICAL WIND SHEAR. ANIMATED INFRARED IMAGERY SHOWS DEEP CONVECTIVE CLOUDS OVER THE CENTER AND TO THE SOUTHWEST OF THE LOW LEVEL CIRCULATION CENTER (LLCC). A 041022Z AMSU IMAGE SHOWS DEEP CONVECTION ASSOCIATED WITH THE LLCC AND ONLY DISJOINTED POCKETS OF SHALLOW CONVECTION IN THE BANDING STRUCTURE. ALSO EVIDENT IN THE AMSU IMAGE IS DRY AIR IN THE MID-LEVELS STARTING TO WRAP INTO THE WESTERN PERIPHERY. B. THE CURRENT POSITION AND INTENSITY ARE BASED ON DVORAK ESTIMATES FROM RJTD, PGTW AND KNES, ALONG WITH RADAR OBSERVATIONS FROM VHHH. 3. FORECAST REASONING. A. THE FORECAST PHILOSOPHY HAS NOT SIGNIFICANTLY CHANGED SINCE THE LAST PROGNOSTIC REASONING BULLETIN. B. TS 08W WILL CONTINUE TO TRACK NORTHWESTWARD AND MAKE LANDFALL WEST OF HONG KONG WITHIN THE NEXT 12 HOURS. THE SYSTEM IS EXPECTED TO MAINTAIN INTENSITY AS IT INITIALLY STARTS TO INTERACT WITH LAND DUE TO FAVORABLE SEA SURFACE TEMPERATURES AND GOOD SOUTHWESTWARD OUTFLOW, BUT THEN THE SYSTEM WILL RAPIDLY DISSIPATE ONCE THE CENTER MOVES OVER THE COAST. THE SYSTEM IS UNDER THE STEERING INFLUENCE OF A LOW- TO MID-LEVEL RIDGE LOCATED IN SOUTHEAST CHINA AND THIS PATTERN WILL CONTINUE TO GUIDE THE REMNANTS OF THE SYSTEM WESTWARD AFTER LANDFALL. AVAILABLE NUMERIC MODEL GUIDANCE INCLUDES FORECAST TRACKS TOWARD THE NORTHWEST THEN ALMOST DUE WEST AFTER LANDFALL.// NNNN