Japanese weather officials are warning of bands of heavy rain clouds that will likely form over the Shikoku region, western Japan.
The Meteorological Agency says warm and damp air is flowing toward a front accompanied by a low pressure system that stretches off the southern coast of Kyushu to Kanto, making atmospheric conditions very unstable.
Heavy rain is pounding some parts of the Okinawa-Amami and Shikoku regions.
Between 4 a.m. and 5 a.m. on Tuesday, 60.5 millimeters of rain were recorded in the city of Nago, Okinawa Prefecture, and 59 millimeters in the city of Sukumo, Kochi Prefecture.
The agency is warning of a high risk of landslides in some parts of Okinawa.
Bands of heavy rain clouds are expected to develop over the four prefectures of Shikoku — Kochi, Tokushima, Ehime and Kagawa — before Tuesday noon, as developed rain clouds flow in. That would increase precipitation and quickly raise the risk of disasters.
Downpours are expected to continue in Okinawa on Tuesday morning.
Some parts of the Kinki, Tokai and Kanto-Koshin regions are expected to have heavy rains and thunder through Tuesday night.
During the 24-hour period through Wednesday morning, up to 250 millimeters of rain are forecast for Tokai, 200 millimeters for Shikoku and Kanto-Koshin, 150 millimeters for Kinki and 120 millimeters for Okinawa and the Izu Islands.
The Meteorological Agency is warning of landslides, flooding of low-lying areas, swelling rivers and lightning strikes, as well as gusts, including tornadoes, and hail.
The agency is also calling on people to take safety measures, including moving into sturdy buildings, if there are any signs of developed thunderclouds approaching.