Japanese weather officials are urging residents in the southern regions of Kyushu and Shikoku to stay alert for heavy rain caused by Tropical Storm Songda.

They say downpours are expected through Saturday, and that people in low-lying areas should stay vigilant for possible flooding, as well as strong winds, high waves and lightning.

The Meteorological Agency says Songda was moving west-northwest at 35 kilometers per hour over waters 140 kilometers southeast of Yakushima Island as of Friday midnight.

Officials say the storm has a central atmospheric pressure of 1000 hectopascals, with maximum winds of about 72 kilometers per hour, and gusts of up to 108 kilometers per hour.

Forecasters say the storm will not approach Japan's main island any more than it has, but it will cause warm and damp air to flow toward the archipelago.

Atmospheric conditions in southern Kyushu, the Amami region and Shikoku will be unstable through Sunday.

Many areas are likely to experience thunder and heavy rain. Precipitation will exceed 50 millimeters per hour in some places.

Maximum rainfall in the 24 hours through late Saturday afternoon is likely to reach 250 millimeters in southern Kyushu and Shikoku, and 150 millimeters in the Amami region.