Japan: Severe weather ongoing in southern and central regions as of Aug. 20 /update 6

Event

Heavy rains are ongoing across Japan as of Aug. 20. The Japan Meteorological Administration has issued the following warnings:

• Purple (the second-highest level on a four-tier scale) warnings for landslides due to heavy rain: Western Ehime, western Kagoshima, Tokushima, and central Yamaguchi prefectures.

• Red warnings for heavy rainfall, flooding, and landslides: Western Aichi, eastern Ehime, southern Hyogo, the rest of Kagoshima, Kochi, southern Miyazaki, western Shizuoka, and western Yamaguchi prefectures.

• Yellow heavy rain, thunderstorms, flooding, and landslide advisories: The rest of the affected area.

Adverse weather will likely continue in the coming days; authorities may expand evacuation orders if weather conditions persist or worsen.

The low-pressure system is likely to bring at least 15 cm (6 inches) of rainfall to the Shikoku Region, and 12 cm (4.5 inches) of rainfall to northern Kyushu as well as the Chugoku Region through late Aug. 21. The Tokai Region and southern Kyushu are forecast to receive 10 cm (4 inches), while the Kinki Region is likely to receive 8 cm (3 inches) of rainfall.

At the height of the storm, authorities had ordered the evacuation of at least 2.6 million people. Most have since returned home, leaving 132,166 people still under evacuation orders in Ehime, Fukuoka, Gifu, Hiroshima, Hyogo, Kumamoto, Kyoto, Nagasaki, Nagano, Niigata, Osaka, Saga, Tokushima, Wakayama, and Yamaguchi prefectures. At least 69 rivers have overflowed in worst-hit regions, most in Saga, Shimane, Fukuoka, Hiroshima, and Gifu prefectures; Niho River in the Fushino River system, Yamaguchi Prefecture is also in danger of flooding. Reports indicate landslides and flooding have killed at least eight people, including three in Okaya City, Nagano Prefecture, four in Nagasaki Prefecture, and one in Kagoshima Prefecture as of early Aug. 20. Reports also indicate damage to multiple structures and flooding of around 4,929 buildings. Additionally, several landslides have also occurred in the affected region. Officials will likely provide further updates on damage and casualties in the coming days.

Hazardous Conditions
Sustained heavy rainfall could trigger flooding in low-lying communities near rivers, streams, and creeks. Urban flooding is also possible in developed areas with easily overwhelmed stormwater drainage systems. Sites located downstream from large reservoirs or rivers may be subject to flash flooding after relatively short periods of intense rainfall. Landslides remain possible in hilly or mountainous areas, especially where the soil has become saturated by heavy rainfall. Disruptions to electricity and telecommunications services are possible where significant flooding or landslides impact utility networks.

Transport
Multiple railways and train lines in affected areas have experienced disruptions, with trains suspended or delayed due to heavy rain. Floodwaters and debris flows may render some bridges, rail networks, or roadways impassable, impacting overland travel in and around affected areas. Ponding on road surfaces could cause hazardous driving conditions on regional highways. Authorities could temporarily close some low-lying routes that become inundated by floodwaters. Severe weather could also trigger flight delays and cancellations at regional airports. Authorities may temporarily suspend port operations or close beach fronts along the Philippine Sea, East China Sea, and the Sea of Japan if strong winds trigger hazardous sea conditions. Flooding could block regional rail lines; freight and passenger train delays and cancellations are possible in areas that see heavy rainfall and potential track inundation.

Localized business disruptions may occur in low-lying areas; some businesses might not operate at full capacity because of flood damage to facilities, possible evacuations, and some employees' inability to reach work sites.

Advice

Monitor local media for weather updates and related advisories. Confirm all transport reservations and business appointments before travel. Make allowances for localized travel delays and potential supply chain disruptions where flooding has been forecast. Do not drive on flooded roads. Charge battery-powered devices in the case of prolonged electricity outages.

Resources

Japan Meteorological Administration