Japan: Adverse weather forecast across parts of Hokkaido and northern Honshu through at least March 16

Event

Heavy rain and strong winds are forecast across parts of Hokkaido and northern Honshu through at least March 16. The Japan Meteorological Agency (JMA) has issued red (second level on a three-tier scale) storm warnings across western Akita and western Yamagata prefectures as well as Hiyama and Oshima regions in Hokkaido Prefecture and Sado Island in Niigata Prefecture. Yellow advisories are in effect for the rest of the affected area. Authorities have warned that a storm tracking eastwards is forecast to reach northern Japan late March 15, bringing lightning, tornadoes, hail, and heavy rain to western and eastern Japan March 15. Authorities will likely issue new alerts or update/rescind existing advisories as the storm transits the region over the coming hours.

Hazardous Conditions
The storm could produce rounds of heavy precipitation (including rain and snow), strong winds, and isolated thunderstorm activity in Hokkaido and northern Honshu. Where precipitation falls as rain, flash and areal flooding is possible. Such flooding is possible in low-lying communities near watercourses and other large bodies of water, as well as in urban areas with easily overwhelmed stormwater drainage systems. Sites located downstream of large reservoirs may be subject to flash flooding after relatively short periods of intense rainfall.

Precipitation could fall as snow in the higher elevations over the coming days. Wind gusts could cause blowing and drifting snow; decreased visibility is likely in mountainous areas. Rain-induced landslides cannot be discounted in areas of elevated terrain; there is also the possibility of avalanches in mountainous areas where the snowpack has become unstable due to heavy snowfall. Power outages could occur throughout the affected area.

Transport
Floodwaters and related debris may render some bridges, rail networks, or roadways impassable, impacting overland travel in and around the affected area. Flooding in urban areas could also result in significant traffic congestion.

The disruptive weather will likely cause some delays and cancellations at airports in the region. All Nippon Airways has warned of possible flight cancellations or delays at Shonai Airport (SYO) due to strong winds and at New Chitose (CTS), Wakkanai (WKJ), Nemuro-Nakashibetsu (SHB), Okhotsk-Monbetsu (MBE), Kushiro (KUH), and Hakodate (HKD) airports due to strong winds and snow. Japan Airlines has canceled some flights at Sapporo Okadama (OKD), Hakodate (HKD), and Okushiri (OIR) airports while flights at Rishiri (RIS), Memanbetsu (MMB), New Chitose (CTS), Sapporo Okadama (OKD), Hanamaki (HNA), Tokachi-Obihiro (OBO), Asahikawa (AKJ), Kushiro (KUH), and Hakodate (HKD) airports may experience irregular operations due to strong winds and snow. Additional flight delays or cancellations are likely across Hokkaido and northern Honshu.

The Japan National Route 48 connecting Miyagi and Yamagata prefectures was closed due to an avalanche in Sakunami, Aoba Ward, Sendai City early March 14; snow removal works are underway and the road has been partially reopened. The Sendai Local Meteorological Observatory has issued an avalanche warning in western Miyagi Prefecture due to the risk of snow melting with rising temperatures; authorities warn residents to be vigilant of possible avalanches on slopes with a large volume of snow.

JR East has warned of train delays and cancelations in the Shin'etsu and Tohoku regions; train services on the Tohoku, Kamaishi, Gono, Tadami, Oito, and Yonesaka lines remain suspended. Further train delays and cancelations are likely in areas that see heavy rainfall, strong winds, or heavy snow.

The winter weather will likely cause additional ground and air transport disruptions across the affected area over the coming days. Traffic and commercial trucking delays are possible along regional highways. Difficult and potentially dangerous driving conditions are also likely on secondary and rural roadways in the affected states as maintenance crews prioritize clearing major routes. Authorities could close stretches of a highway if driving conditions become too hazardous. Gusty winds may threaten to topple high-profile vehicles throughout the affected area.

Advice

Monitor local media for updated weather information. Verify road conditions before driving in areas where heavy snowfall is forecast. Allow extra time to reach destinations in these areas and carry an emergency kit and warm clothes if driving is necessary, especially on secondary or rural routes that could become impassable. Plan accordingly for delivery delays if routing shipments by truck through the affected area. Confirm flights. Charge battery-powered devices in the case of prolonged electricity outages.

Resources

Japan Meteorological Agency