Japan: Tropical Depression Yun-yeung tracking north-northeastward toward Shizuoka Prefecture as of early Sept. 9 /update 6

Event

Tropical Storm Yun-yeung is tracking north-northeastward in the Philippine Sea and is approaching Shizuoka Prefecture early Sept. 9. As of 06:00 JST, the system's center of circulation was approximately 156 km (97 miles) southwest of Yokosuka, Kanagawa Prefecture.

Forecast models indicate that the weather system will make landfall over northern Suruga Bay over the coming hours. Yun-yueng is forecast to continue to track north-northeastward as a tropical depression over Yamanashi, far western Saitama, and Gunma prefectures through the afternoon of Sept. 9, before tracking over far western Fukushima and far eastern Niigata prefectures and dissipating over northwestern Yamagata Prefecture early Sept. 10. Some uncertainty remains in the track and intensity forecast, and changes could occur in the coming days.

As of early Sept 9, the Japan Meteorological Agency (JMA) has issued a bulletin regarding the storm system, warning that linear rain belts ahead of the storm system are already causing heavy downpours across parts of Kanto-Koshin and Tohuku regions. Rainfall totals of around 15 cm (6 inches) are expected in these regions late Sept. 8-9. The JMA has also issued purple heavy rain and landslide warnings (the highest level on a four-tier scale) across southern Chiba, northern Ibaraki, and eastern Fukushima prefectures and red heavy rain and landslide warnings across the rest of Chiba Prefecture. Authorities will likely issue new warnings or update existing advisories throughout the system's progression in the coming days.

Authorities have issued black emergency safety assurance evacuation warnings (the highest level on a three-tier scale) for more than 321,000 people in Iwaki City in Fukushima Prefecture. Lower-level purple and red evacuation orders have been ordered for tens of thousands of other people across parts of Chiba, Fukushima, and Ibaraki prefectures. Authorities may issue further evacuation orders in the coming hours.

All Nippon Airways (ANA) canceled flights to and from Hachijojima Airport (HAC) in southern Izu Islands and Shizuoka Airport (FSZ) Sept. 8. Japan Airlines (JAL) stated domestic flights to and from Tokyo's Haneda Airport (HND) and Narita International Airport (NRT) were experiencing irregular operations Sept. 8 due to the passage of the storm. As of early Sept. 9, most flights are operating normally.

JR East has suspended rail services on all lines in Chiba Prefecture, including the Uchibo Line between Tateyama and Awa Kamogawa and the Sotobo Line between Katsuura and Awa Kamogawa. The Joban Line is also suspended between Katsuta in Ibaraki Prefecture and Yamashita in Miyagi Prefecture. Several roads across the affected regions have been closed due to flooding and landslides, including sections of the Higashi-Kanto Expressway, the Ken-O Expressway, and the Tokyo Bay Aqua-Line; most roads have since been reopened. Around 3,450 homes in Ibaraki Prefecture, 4,780 in Chiba Prefecture, and 4,800 in Fukushima Prefecture are without power as of early Sept. 9.

Sustained heavy rainfall could trigger flooding in low-lying areas and those with easily overwhelmed drainage systems. If weather conditions prove hazardous, localized evacuations, flash flooding, and landslides are possible.

The inclement weather could trigger localized business, transport, and utility disruptions and render some bridges or roadways impassable. Flight disruptions at regional airports and temporary closures of ports are also possible. Stagnant pools of water during and after flooding increase insect- and waterborne diseases, such as dengue fever, cholera, and malaria. Exposure to raw sewage and other hazardous materials mixed with floodwaters poses a serious health threat.

Advice

Activate contingency plans in areas where officials forecast tropical storm conditions. Heed any evacuation orders that may be issued. Use extreme caution in low-lying coastal areas and near streams, creeks, and other waterways due to the potential for severe flooding and storm surge. Stockpile water, batteries, and other essentials in advance. Charge battery-powered devices when electricity is available; restrict the use of cellular phones to emergencies only. Power down mobile devices when not in use. Keep important documents and necessary medications in waterproof containers. Observe strict food and water precautions, as municipalities could issue boil-water advisories following flooding events. Take precautions against insect- and waterborne diseases in the coming weeks.

Plan accordingly for protracted commercial, transport, and logistics disruptions in areas in the path of the storm, especially if vital infrastructure is damaged. Seek updated information on road conditions before driving or routing shipments through areas where flooding has occurred. Confirm flights before checking out of hotels or driving to the airport; clearing passenger backlogs may take several days in some locations.

Resources

Joint Typhoon Warning Center (JTWC)
Japan Meteorological Agency (JMA)