WWJP71 RJTD 170600 IMPORTANT WARNING FOR NAHA NAVTEX AREA 170600UTC ISSUED AT 170900UTC WARNING(DENSE FOG) SEA WEST OF NAGASAKI, SEA SOUTHWEST OF MESHIMA, SOUTHERN PART OF EAST CHINA SEA POOR VIS 0.3 MILES OR LESS IN PLACES NXT WARNING WILL BE ISSUED BEFORE 171500UTC =