A man died Wednesday in Kumamoto Prefecture after falling into a swollen river as heavy rain continued in western Japan.

Kumamoto city government employee Kenichi Nakamura, 41, fell into the river around 4:40 a.m. while trying to set up "road closed" signs on a bridge as the river was swollen due to the rain, police said. He was found in a lake downstream at around 9:20 a.m.

According to the police, Nakamura found the river flowing over the bridge, which has no handrails, while he was out to check hazardous places after the downpour. A flood warning was issued in the city at the time, the police said.

Nakamura slipped and fell from the bridge while working with another city employee to set up the signs on both sides, the police said.

On Wednesday, the Japan Meteorological Agency alerted eastern and western Japan as well as the Pacific side of the Kyushu region to the possibility of landslides and flooding as heavy rain, accompanied by thunder, may fall in the areas from Wednesday to Thursday morning.

Warm, humid air from the south is flowing toward a rain front, which extends to the Sea of Japan coast, making the atmosphere unstable on the south side of the rain front, the agency said. Torrential rain of 40-60 millimeters an hour hit eastern and western Japan as well as the Pacific side of Kyushu.

A record 89 mm of rain per hour was logged at Mt. Hoyoshi in Kagoshima Prefecture, while 107 mm rain, also a record, fell in Cape Sata in the same prefecture.

Cumulative rainfall through 6 a.m. Thursday may reach 300 mm in southern Kinki, 200 mm in each of southern Kyushu and the Pacific side of Shikoku, 180 mm in Tokai, and 150 mm each in northern Kyushu and the Koshin region.

The rain front is expected to move slowly to near the southern shore of Japan's main island, according to the agency. It may stall in eastern and western Japan, bringing more rain, it said.