Heavy rain is pounding the southwestern Japanese region of Kyushu as well as Yamaguchi Prefecture. One person is unaccounted for in Oita Prefecture following a landslide. Weather officials are urging people to stay alert for landslides and flooding.

They say warm, moist air from the south is flowing into a front near the main island of Honshu, making atmospheric conditions extremely unstable in western and eastern Japan.

Bands of heavy rain clouds have developed, causing downpours in Yamaguchi. Officials with the Japan Metrological Agency say more could develop in the area as well as Kyushu.

Parts of Yamaguchi and Fukuoka Prefecture are estimated to have received about 100 millimeters of rainfall in the one-hour period through early Saturday. Some rivers have overflown in Yamaguchi Prefecture.

Officials say the risk of landslides is rising in Oita, Saga, Fukuoka, Nagasaki, Kumamoto, Miyazaki, Yamaguchi, Hiroshima and Ehime prefectures, with warnings already issued in some areas.

Unstable conditions are expected to continue through Saturday, bringing downpours and lightning. Kyushu may see localized rainfall.

Rainfall in the 24-hour period through Sunday morning is expected to reach up to 200 millimeters in northern and southern Kyushu; 180 millimeters in Tokai; 150 millimeters in Kinki; 120 millimeters in Shikoku and Kanto-Koshin; 100 millimeters in Hokuriku; and 60 millimeters in Chugoku region.

Weather officials are warning of landslides, flooding in low-lying areas, swollen rivers, lightning, and strong winds including tornadoes.

The officials say landslides could still occur and river levels may rise even after it stops raining. They are urging people to refrain from going near rivers, and to ensure their safety. Officials are calling on people to check the latest evacuation information from local governments.

One person is unaccounted for after mud swept away a house in Oita Prefecture.

The rain has flooded some 10 houses in Yamaguchi City.