Typhoon Dolphin was a powerful tropical cyclone that produced the first typhoon-force winds on Guam since Typhoon Pongsona in 2002. The seventh named storm of the 2015 Pacific typhoon season, Dolphin formed on May 6 in the vicinity of the Federated States of Micronesia (FSM). Moving eastward at first, the storm slowly organized before beginning a north and west-northwest trajectory. Dolphin intensified into a typhoon before passing between Guam and Rota on May 15, producing typhoon-force winds on both islands. It later rapidly intensified as it curved to the north. The American-based Joint Typhoon Warning Center (JTWC) designated Dolphin as a super typhoon, while the Japan Meteorological Agency (JMA) estimated 10 minute sustained winds of 185 km/h (115 mph). Dolphin turned to the northeast and weakened, becoming extratropical on May 20 and exiting the western Pacific basin on May 24.