Tracking along the southern periphery of a subtropical ridge, the cyclone decelerated. Lynn gradually intensified, though this process briefly halted on October 17. Early the next day, the JMA reported that Lynn had deepened into a severe tropical storm. Shortly thereafter, radar data and satellite imagery revealed the formation of an eye in diameter, and thus the JTWC upgraded Lynn into a typhoon, though post-storm analysis noted that Lynn could have been a typhoon before then. Also around this time, the JMA designated Lynn as a typhoon. At midday, Lynn made its closest approach to Guam, passing around northeast of the island. Three hours later, Lynn passed southwest of Tinian before proceeding west-northwest.
