WTJP33 RJTD 051500 WARNING 051500. WARNING VALID 061500. STORM WARNING. SEVERE TROPICAL STORM 1511 NANGKA (1511) 985 HPA AT 10.9N 162.1E MARSHALLS MOVING WEST 12 KNOTS. POSITION FAIR. MAX WINDS 50 KNOTS NEAR CENTER. RADIUS OF OVER 30 KNOT WINDS 120 MILES. FORECAST POSITION FOR 060300UTC AT 11.7N 159.6E WITH 50 MILES RADIUS OF 70 PERCENT PROBABILITY CIRCLE. 980 HPA, MAX WINDS 55 KNOTS NEAR CENTER. FORECAST POSITION FOR 061500UTC AT 12.6N 157.4E WITH 75 MILES RADIUS OF 70 PERCENT PROBABILITY CIRCLE. 975 HPA, MAX WINDS 60 KNOTS NEAR CENTER. JAPAN METEOROLOGICAL AGENCY.=