Highest weather warning issued for southwest Japan’s Unnan city, heavy rain predicted for mainland

Extremely heavy rains affecting parts of southwestern Japan over the past couple of days forced hundreds of thousands to evacuate. Severe weather continues in the region and is forecast to spread to mainland Japan, all the way to Tohoku.

On Monday, July 12, 2021, the Japan Meteorological Agency (JMA) has issued a Level 5 weather warning — the highest — for the entire western Japan city of Unnan, Shimane Prefecture.

All of the approximately 13 700 households in the city, and their roughly 36 800 residents, are subject to the warning, The Mainichi reports.

JMA says that it appears that around 100 mm (3.93 inches) of rain fell in a single hour in the area around Unnan.

Western Japan's Sanin region has also seen extremely heavy localized rain and thunder. The JMA says the dangers of a landslide or flood disaster have risen precipitously and is urging people to take caution.

JMA is also warning residents on the Japanese mainland of potential mudslides and floods through July 13.

Thunderstorms are forecast for wide areas from the Tohoku region to the west.

Power outages have already affected Tokyo and five other prefectures on July 11.

According to the NHK, more than 90 000 households in Kagoshima, Miyazaki, and Kumamoto prefectures received evacuation orders and 236 000 people got the highest (level five), 'beyond evacuation' warning on July 10.

According to The Mainichi, this is the first time JMA has issued a Level 5 torrential rain alert (on a scale of 1 to 5) this year. The alert was lowered to a warning, Level 3, in the afternoon.

In just 12 hours on July 10, Kagoshima prefecture recorded around 330 mm (13 inches) of rain. Its average July rainfall is 318.9 mm (12.56 inches).

A JMA weather station in Satsuma, Kagoshima, recorded 96.5 mm (3.79 inches) of rain per hour, setting a new hourly rainfall record for the town.

In 72 hours to 18:40 LT on July 10, Satsuma Kashiwabaru recorded 539 mm (21.2 inches) of rain.

Kano in Tottori, Tottori Prefecture registered 464.5 mm (18.2 inches) over the same period, Ebino in Miyazaki 427 mm (16.8 inches), and Daisen in Tottori 387 mm (15.2 inches).

Featured image credit: JMA/Himawari-8. Acquired at 08:30 UTC on July 12, 2021.