WTJP31 RJTD 041500 WARNING 041500. WARNING VALID 051500. TYPHOON WARNING. TYPHOON 1821 JEBI (1821) 975 HPA AT 40.9N 138.8E SEA OF JAPAN MOVING NORTHNORTHEAST 42 KNOTS. POSITION FAIR. MAX WINDS 65 KNOTS. RADIUS OF OVER 50 KNOT WINDS 60 MILES SOUTHEAST SEMICIRCLE AND 30 MILES ELSEWHERE. RADIUS OF OVER 30 KNOT WINDS 300 MILES SOUTHEAST SEMICIRCLE AND 120 MILES ELSEWHERE. FORECAST POSITION FOR 050300UTC AT 48.1N 138.8E WITH 40 MILES RADIUS OF 70 PERCENT PROBABILITY CIRCLE. 974 HPA, MAX WINDS 55 KNOTS. BECOMING EXTRATROPICAL LOW. FORECAST POSITION FOR 051500UTC AT 51.8N 136.5E WITH 60 MILES RADIUS OF 70 PERCENT PROBABILITY CIRCLE. 976 HPA, MAX WINDS 45 KNOTS. BECOMING EXTRATROPICAL LOW. JAPAN METEOROLOGICAL AGENCY.=