WTJP31 RJTD 302100 WARNING 302100. WARNING VALID 312100. TYPHOON WARNING. TYPHOON 1821 JEBI (1821) 925 HPA AT 17.8N 144.8E MARIANAS MOVING WEST 12 KNOTS. POSITION GOOD. MAX WINDS 100 KNOTS NEAR CENTER. RADIUS OF OVER 50 KNOT WINDS 50 MILES. RADIUS OF OVER 30 KNOT WINDS 180 MILES NORTH SEMICIRCLE AND 150 MILES ELSEWHERE. FORECAST POSITION FOR 310900UTC AT 18.4N 142.4E WITH 40 MILES RADIUS OF 70 PERCENT PROBABILITY CIRCLE. 915 HPA, MAX WINDS 105 KNOTS NEAR CENTER. FORECAST POSITION FOR 312100UTC AT 19.3N 140.1E WITH 60 MILES RADIUS OF 70 PERCENT PROBABILITY CIRCLE. 905 HPA, MAX WINDS 110 KNOTS NEAR CENTER. JAPAN METEOROLOGICAL AGENCY.=