WTJP22 RJTD 301800 WARNING 301800. WARNING VALID 011800. WARNING IS UPDATED EVERY 6 HOURS. TYPHOON WARNING. SEVERE TROPICAL STORM 1618 CHABA (1618) 985 HPA AT 15.4N 136.0E SEA EAST OF PHILIPPINES MOVING NORTHNORTHWEST 10 KNOTS. POSITION FAIR. MAX WINDS 55 KNOTS NEAR CENTER. RADIUS OF OVER 50 KNOT WINDS 30 MILES. RADIUS OF OVER 30 KNOT WINDS 150 MILES. FORECAST POSITION FOR 010600UTC AT 17.4N 134.1E WITH 40 MILES RADIUS OF 70 PERCENT PROBABILITY CIRCLE. 980 HPA, MAX WINDS 60 KNOTS NEAR CENTER. FORECAST POSITION FOR 011800UTC AT 19.4N 132.1E WITH 60 MILES RADIUS OF 70 PERCENT PROBABILITY CIRCLE. 975 HPA, MAX WINDS 65 KNOTS NEAR CENTER. EXTENDED OUTLOOK. FORECAST POSITION FOR 021800UTC AT 23.7N 128.4E WITH 110 MILES RADIUS OF 70 PERCENT PROBABILITY CIRCLE. 960 HPA, MAX WINDS 80 KNOTS NEAR CENTER. FORECAST POSITION FOR 031800UTC AT 28.5N 128.5E WITH 220 MILES RADIUS OF 70 PERCENT PROBABILITY CIRCLE. 950 HPA, MAX WINDS 85 KNOTS NEAR CENTER. JAPAN METEOROLOGICAL AGENCY.=