An expert on the mechanism of typhoons is warning of torrential rains hitting parts of Japan located far from where Typhoon Shanshan is approaching.

Tsuboki Kazuhisa, a professor at Nagoya University and Yokohama National University, says Typhoon Shanshan is extremely dangerous as it is rare for a storm to keep developing even as it nears southern Kyushu, which is around 30 degrees north latitude.

He says the typhoon could continue developing until it makes landfall and hit land with maximum force.

Tsuboki is urging people to take precautions not only southern Kyushu, which is close to the typhoon, but also in areas on the main Japanese island of Honshu as far east as the Kanto Koshin region, which includes Tokyo.

These areas could see downpours triggered by a massive inflow of vapor, in what is called a "predecessor rain event."

Tsuboki says Typhoon Shanshan's path is uncertain, so people should stay updated with the latest forecasts.