WTJP21 RJTD 121200 WARNING 121200. WARNING VALID 131200. WARNING IS UPDATED EVERY 6 HOURS. STORM WARNING. SEVERE TROPICAL STORM 1702 MERBOK (1702) UPGRADED FROM TROPICAL STORM 990 HPA AT 22.0N 114.4E SOUTH CHINA SEA MOVING NORTH 10 KNOTS. POSITION FAIR. MAX WINDS 50 KNOTS NEAR CENTER. RADIUS OF OVER 30 KNOT WINDS 90 MILES. FORECAST POSITION FOR 130000UTC AT 23.9N 114.2E WITH 30 MILES RADIUS OF 70 PERCENT PROBABILITY CIRCLE. 1004 HPA. BECOMING TROPICAL DEPRESSION. FORECAST POSITION FOR 131200UTC AT 25.6N 115.2E WITH 60 MILES RADIUS OF 70 PERCENT PROBABILITY CIRCLE. 1004 HPA. BECOMING TROPICAL DEPRESSION. JAPAN METEOROLOGICAL AGENCY.=