Weather officials are warning of localized thunderstorms over a wide area of Japan through Saturday. They are calling for caution against landslides and flooding.
The Meteorological Agency said on Friday that warm, humid air is blowing toward a rain front and a low-pressure system near Japan's main island of Honshu. This is causing unstable atmospheric conditions from the Pacific side of eastern Japan to western Japan. Rainclouds are developing in the Kanto and Tokai regions.
In Matsuyama City, western Japan, where a landslide hit a residential area, the total rainfall from Wednesday to 4 a.m. Friday reached 197.5 millimeters. The amount is close to 90 percent of the city's monthly average rainfall for July. The prefecture has issued a landslide alert.
Weather officials say the rain front is likely to linger over western Japan and the Pacific side of eastern Japan until Saturday. They say localized torrential rain accompanied by thunder is possible on the Pacific side of eastern Japan through Friday evening and in western Japan through Saturday.
In the 24-hour period until Saturday morning, up to 120 millimeters of rain is possible in southern Kyushu, and as much as 100 millimeters in the Kanto-Koshin, Tokai, Kinki and Shikoku regions, as well as northern Kyushu.
The officials say the rain is expected to intensify again in the Shikoku region, where the landslide occurred in Matsuyama City. They say the risk of landslides could increase in areas that may have little rainfall, as the ground is saturated.