WTJP21 RJTD 040600 WARNING 040600. WARNING VALID 050600. WARNING IS UPDATED EVERY 6 HOURS. TYPHOON WARNING. SEVERE TROPICAL STORM 2521 MATMO (2521) 985 HPA AT 18.4N 115.1E SOUTH CHINA SEA MOVING WEST 14 KNOTS. POSITION FAIR. MAX WINDS 55 KNOTS NEAR CENTER. RADIUS OF OVER 50 KNOT WINDS 40 MILES. RADIUS OF OVER 30 KNOT WINDS 240 MILES NORTHEAST SEMICIRCLE AND 150 MILES ELSEWHERE. FORECAST POSITION FOR 041800UTC AT 19.5N 112.6E WITH 25 MILES RADIUS OF 70 PERCENT PROBABILITY CIRCLE. 975 HPA, MAX WINDS 65 KNOTS NEAR CENTER. FORECAST POSITION FOR 050600UTC AT 20.8N 110.5E WITH 35 MILES RADIUS OF 70 PERCENT PROBABILITY CIRCLE. 965 HPA, MAX WINDS 75 KNOTS NEAR CENTER. EXTENDED OUTLOOK. FORECAST POSITION FOR 060600UTC AT 22.6N 106.5E WITH 55 MILES RADIUS OF 70 PERCENT PROBABILITY CIRCLE. 994 HPA, MAX WINDS 35 KNOTS. FORECAST POSITION FOR 070600UTC AT 23.5N 102.7E WITH 100 MILES RADIUS OF 70 PERCENT PROBABILITY CIRCLE. 1008 HPA. BECOMING TROPICAL DEPRESSION. JAPAN METEOROLOGICAL AGENCY.=