Talas will unleash flooding rain and potentially damaging wind as it plows through the Japan mainland Friday and Saturday.

Southwestern Honshu, together with smaller Shikoku, will likely bear the brunt of the heaviest rain and strongest wind, as landfall of the strong tropical storm is forecast to happen in this area on Friday, Eastern Time.

On Thursday, Talas, a huge tropical storm, was centered about 500 miles southwest of Tokyo. Highest sustained winds were between 60 and 65 mph, whereas movement was toward the northwest at 6 mph. There is at least a small chance that Talas become a typhoon before landfall.

First landfall is forecast for the island of Shikoku or nearby Honshu on Friday afternoon or evening, Eastern Time.

Rugged hills of southwestern Japan near the path of the storm’s center will be at greatest risk of flooding rain and mudslides. Highest rainfall is likely to be between 15 and 20 inches.

Meanwhile, localized torrential rain was already pelting central and southern Japan well ahead of Talas on Thursday.

For instance, rainfall was locally excessive in the hills bordering the western Kanto Plain of central Honshu. Rainfall was 8.4 inches in 24 hours at Maebashi, data accessed by AccuWeather.com showed.

In the hills of Saitama prefecture, which abuts Tokyo, rainfall was about 14 inches within 24 hours, according to data published online by the Japan Meteorological Agency (JMA). Such rainfall can trigger severe flooding.