WTJP21 RJTD 031200 WARNING 031200. WARNING VALID 041200. WARNING IS UPDATED EVERY 6 HOURS. TYPHOON WARNING. TYPHOON 1821 JEBI (1821) 945 HPA AT 28.6N 132.6E SEA SOUTH OF JAPAN MOVING NORTH 11 KNOTS. POSITION GOOD. MAX WINDS 85 KNOTS NEAR CENTER. RADIUS OF OVER 50 KNOT WINDS 120 MILES EAST SEMICIRCLE AND 90 MILES ELSEWHERE. RADIUS OF OVER 30 KNOT WINDS 240 MILES EAST SEMICIRCLE AND 180 MILES ELSEWHERE. FORECAST POSITION FOR 040000UTC AT 32.1N 133.9E WITH 40 MILES RADIUS OF 70 PERCENT PROBABILITY CIRCLE. 945 HPA, MAX WINDS 85 KNOTS NEAR CENTER. FORECAST POSITION FOR 041200UTC AT 38.6N 137.7E WITH 80 MILES RADIUS OF 70 PERCENT PROBABILITY CIRCLE. 965 HPA, MAX WINDS 65 KNOTS NEAR CENTER. EXTENDED OUTLOOK. FORECAST POSITION FOR 051200UTC AT 51.5N 137.4E WITH 150 MILES RADIUS OF 70 PERCENT PROBABILITY CIRCLE. 976 HPA, MAX WINDS 40 KNOTS. BECOMING EXTRATROPICAL LOW. JAPAN METEOROLOGICAL AGENCY.=