05 Sep 2023 | 10:08 AM UTC
Japan: Adverse weather forecast across much of the country through at least Sept. 8
Severe weather forecast across much of Japan through at least Sept. 8. Flooding, landslides, and associated disruptions likely.
Event
Severe weather is forecast across much of Japan through at least Sept. 8. As of Sept. 5, the Japan Meteorological Agency (JMA) has issued a weather bulletin warning that a weather front stretching over much of the country and a storm system near Shikoku will bring heavy rainfall to northern and western regions from Sept. 6 and eastern regions from Sept. 7. Heavy rainfall may be accompanied by thunderstorms, strong wind gusts, lightning, hail, and possible tornadoes. Rainfall totals of around 25 cm (10 inches) are forecast in Shikoku Region, 12 cm (5 inches) in Hokuriku and Kinki regions, 10 cm (4 inches) in Chugoku and Tohoku regions, and 8 cm (3 inches) in Kanto Koshin Region late Sept. 6-7. Further heavy rainfall is likely across many areas late Sept. 7-8, with the heaviest rainfall of around 10-15 cm (4-6 inches) likely in Kanto Koshin Region. A tropical system developing south of the Ryukyu Islands may strengthen into a typhoon as it approaches southern mainland Japan Sept. 7-9, bringing further adverse weather in the coming days. Heavy downpours could trigger flooding in low-lying areas and landslides on unstable slopes. Strong winds may cause property damage and power outages.
As of late Sept. 5, the JMA has issued the following weather warnings across the country:
Purple heavy rain/landslide warnings (the second highest level on a three-tier scale): Parts of Shimane Prefecture in Chugoku Region and Niigata Prefecture in Hokuriku Region.
Red heavy rain/inundation warnings: Miyagi Prefecture in Tohoku Region; parts of Niigata and Toyama prefectures in Hokuriku Region, and parts of Shimane and Yamaguchi prefectures in Chuoku Region.
Red heavy rain/landslide warnings: Parts of Yamaguchi Prefecture in Chugoku Region.
Red flood warnings: Parts of Niigata and Toyama prefectures in Hokuriku Region; parts of Shiga prefecture in Kinki Region, and parts of Shimane and Yamaguchi prefectures in Chuoku Region.
Yellow heavy rain/inundation/landslide and flood warnings: Parts of Tohoku, Kanto Koshin, Hokuriku, Kinki, Chugoku, and Northern Kyushu regions and Hokkaido Prefecture.
Yellow storm/gale, high wave, and storm surge warnings: Parts of Tohoku, Kanto Koshin, Tokai, Hokuriku, Kinki, Shikoku, Northern Kyushu, and Southern Kyushu regions and Hokkaido Prefecture.
Yellow thunderstorm warnings: Across much of Japan.
Yellow dense fog warnings: Across most of Hokkaido Prefecture.
Authorities will likely issue new alerts or update/rescind existing advisories as weather conditions develop over the coming days.
Hazardous Conditions
Further sustained heavy rainfall could trigger additional flooding in low-lying communities near rivers, streams, and creeks. Urban flooding is also likely 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 are likely in hilly or mountainous areas, especially where heavy rainfall has saturated the soil.
Authorities could issue additional evacuation orders for flood-prone communities over the coming days. Disruptions to electricity and telecommunications services are likely where significant flooding or landslides impact utility networks.
Transport
Floodwaters and debris flows will likely 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 airports in the affected areas. Flooding could block regional rail lines; freight and passenger train delays and cancellations are likely in areas that see heavy rainfall and potential track inundation.
Localized business disruptions will likely occur in low-lying areas; some businesses might not operate at full capacity because of flood damage to facilities, 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.
