When Lan developed into the ninth typhoon of 2017 at around 18:00 UTC, it had turned slowly northward under the steering influence of a building steering ridge to the southeast and east; early on the next day, the JTWC also upgraded it to a typhoon.
It had turned slowly northward under the steering influence of a building steering ridge to the southeast. It had turned slowly northward under the steering influence of a building steering ridge to east. Lan developed into the ninth typhoon of 2017 at around 18:00 UTC. The JTWC also upgraded it to a typhoon. This was early on the next day.