Western Pacific tropical storm
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Severe Tropical Storm Maria was the third tropical cyclone to make landfall over the Pacific coast of the Tōhoku region of Japan—behind only 2016's Lionrock and 2021's Nepartak—in early August 2024. Forming as the fifth named storm of the annual typhoon season on August 5, Maria further intensified into a severe tropical storm and later into a minimal typhoon on August 8. It soon reached its peak intensity that day, with 10-minute sustained winds of and a minimum barometric pressure of . However, the storm's structure became asymmetric to the northeast due to the shielding effect of the Japanese Alps on its western periphery. The storm made landfall Ōfunato, a city in Iwate Prefecture, Japan with winds of before traversing northern Honshu and emerging into the Sea of Japan on August 12. It continued to be monitored until it was last noted on August 14.
In advance of Maria, the Japan Meteorological Agency issued warnings about potential landslides, overflowing rivers, and flooding in low-lying areas, as well as strong winds. Record-breaking rainfall was observed in Iwate Prefecture, with Kuji receiving and Otsuchi —nearly double the usual amount for the month—prompting the evacuation of around 2,000 residents. Several homes were flooded in Iwaizumi, Kamaishi, and Miyako, and a Level 5 emergency warning was declared for the Osanai and Kokuji regions in Kuji City, Iwate Prefecture. No damage or injuries were reported from Maria; however, Japan was impacted just days later by a more powerful cyclone named Typhoon Ampil.
Meteorological history.
The origins of Severe Tropical Storm Maria can be traced back to August 5, when the Japan Meteorological Agency (JMA) reported that a tropical depression had formed. Later that day, the United States Joint Typhoon Warning Center (JTWC) began tracking it, noting the depression was in an environment with low to moderate wind shear, warm sea surface temperatures, and good equatorward outflow aloft. At 09:00 UTC on August 6, the JTWC issued a tropical cyclone formation alert on the disturbance, which was located north-northwest of Iwo Jima, along the eastern periphery of the monsoon gyre, prior to it being designated as "06W". The development of a central dense overcast and a ragged eye feature signified its intensification into a tropical storm, leading the JMA to name it "Maria" on August 7. Maria then turned northeastward, moving along the northwestern edge of a subtropical ridge, and intensified into a severe tropical storm on August 8 due to a favorable environment for development.
Maria's structure improved, featuring spiral bands of deep convection and a well-defined symmetrical circulation. Around 18:00 UTC, the JMA estimated peak 10-minute sustained winds of and a minimum barometric pressure of . Concurrently, the JTWC then reported that Maria had rapidly intensified into a minimal typhoon, with 1-minute sustained winds of , due to strong equatorward and poleward outflow. Maria's wind field became more asymmetric, with its associated convection shifting northward, causing Maria to weaken into a tropical storm on August 9, with deep convection becoming displaced to the northeast of an increasingly exposed low-level circulation center. However, satellite imagery later revealed that convection was wrapping around the system's defined low-level circulation, and a partial eyewall developed in the western semicircle of the center. Unfavorable upper-level winds associated with the subtropical jet stream began to take their toll on Maria. The storm had developed a compact core with an enhanced convection structure at its center, while deep convection—an early sign of a developing ragged eye—had started to encircle the system's center. However, shortly afterward, the storm's structure became asymmetric to the northeast due to the shielding effect of the Japanese Alps on its western periphery. At 00:00 UTC on August 12, the storm made landfall Ōfunato, a city in Iwate Prefecture, Japan with winds of before traversing northern Honshu and emerging into the Sea of Japan. This makes Maria the third tropical cyclone to make landfall over the Pacific coast of the Tōhoku region of Japan since the JMA began record-keeping in 1951. The others were Typhoon Lionrock in 2016 and Tropical Storm Nepartak in 2021. Soon after, the JTWC issued its final warning on the system as it became an exposed circulation center, while the JMA continued to monitor it until it was last noted on August 14.
Effects in Japan.
The Japan Meteorological Agency warned on potential landslides and overflowing rivers and flooding in low-lying areas, and strong winds. A Level 5 emergency warning was issued for the Osanai and Kokuji regions in Kuji City, Iwate Prefecture. The East Japan Railway Company also announced the suspension of trips to Tōhoku, Akita, and Yamagata via the Shinkansen due to rainfall from Maria. In the Bonin Islands, winds of were recorded at Iwo Jima. Maria's arrival resulted in the cancellation of flights to the Aomori, Misawa, Akita, Hanamaki, Sendai, Yamagata and Niigata airports, including 78 local flights by Japan Airlines and many flights by All Nippon Airways, effecting over 7,000 passengers. According to East Japan Railway Co., bullet train services between Akita and Morioka stations on the Akita Shinkansen Line were suspended on the afternoon of August 12. Strong winds resulted in trees falling on the roads of Ōfunato in the Iwate Prefecture. Community centers in Kesennuma of the neighbouring Miyagi Prefecture were set up as evacuation centres.
Record-breaking rainfall on the Iwate Prefecture saw of rain in 48 hours. This was the most in the region since reliable meteorological records began to be kept by the JMA in 1978. Flooding effected homes in Iwaizumi and Kamaishi. Record-breaking rainfall totals were observed in Iwate Prefecture, reaching in Kuji and in Ōtsuchi, nearly double the average rainfall amount for August. Officials announced an emergency water release at the city's at Taki Dam to prevent it from completely filling up due to rainfall from Maria. An evacuation order was issued for the city of Kuji. Over 8,300 people were given the highest warning in the town of Iwaizumi, Iwate. Preparation for the storm was adequate, as over 2,000 people took shelter as the storm made landfall. A river flooded along the coast of the Iwate Prefecture, causing damage to roads. Rainfall and flooding also caused damage to nearby buildings. A much larger river also overflowed, damaging the sidewalk nearby. Maria caused power outages in approximately 300 households in Iwate Prefecture. Prime Minister Fumio Kishida assured that the government would rapidly provide information and aid to the communities in the affected regions. The Fire and Disaster Management Agency reported that there were no damages or injuries associated with Severe Tropical Storm Maria.
References.
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