- NEW: Lionrock is expected to hit the eastern coast of Japan within 12 hours
- Air travel could be affected, airlines warn
Currently roaring over the western Pacific towards Iwate province , Typhoon Lionrock is moving northeast at 30 kilometers (19 miles) an hour.
CNN meteorologist Chad Myers said the storm was expected to make landfall at about 5pm local time (4am ET), with wind speeds of up to 120 kilometer per hour (75 miles per hour).
He added that cooler waters had weakened the typhoon.
"(I'd expect) higher gusts on mountain tops but nothing devastating," he said. "Storm surge could be three to five meters in some harbors."
Lionrock will bring heavy rain to Japan's northeast provinces, but will miss Tokyo rather than hit the capital directly, as initially expected.
It is forecasted to weaken into a tropical storm by late Tuesday evening, local time.
Japan's Meteorological Agency has issued an advisory
warning of high waves and thunderstorms all up its eastern coast.
Both Japan Airlines and All Nippon Airways have warned of possible disruptions to flights. Routes to and from the Kanto region -- encompassing Tokyo on Honshu, Japan's largest island -- may be affected, the airlines warned.