Tokyo, Aug 23 : Japan's weather agency on Friday said atmospheric conditions are extremely unstable in Japan's Tokai region and other areas, adding that heavy rain is falling in Shizuoka Prefecture.

The Japan Meteorological Agency (JMA) said that warm moist air circling the edge of a high pressure system in the Pacific flowed into the skies over Japan, triggering extremely unstable conditions, Xinhua news agency reported.

Shizuoka City's Shimizu area recorded 317 millimetres of rain in the 24 hours up to 5 a.m. local time, which exceeded the local average rainfall for August, the JMA added.

Landslide alerts have been issued for some parts of Shizuoka Prefecture.

Weather officials said atmospheric conditions in the Tokai region are likely to remain unstable through Saturday.

Extremely heavy localized rains are also forecast for northern Japan, as a low-pressure system accompanying a front is likely to pass over the region, the JMA added.

Rainfall levels in the 24 hours through Saturday morning could reach up to 150 millimetres in the Tokai region, and 120 millimetres in the regions of Hokkaido and Tohoku.

Weather officials are warning that there could be landslides and floods in low-lying areas. They also note that rivers could swell.

The officials are urging people to be careful, as lightning strikes, powerful tornado-like wind gusts and hail could occur.

Severe Tropical Storm Shanshan is expected to move north from the southern part of Japan after it reaches the waters near Tokyo's remote Ogasawara island chain on Sunday.

The storm may approach areas in eastern and western Japan. Officials are urging people to keep abreast of the latest information.

/IANS