Hinnamnor turns deadly, drops nearly 40 inches of rain in South Korea

Hinnamnor made landfall near Geoje, South Korea, around 5 a.m. Tuesday morning, local time, with sustained winds of 89 mph (143 km/h). The deadly storm left roughly 89,000 residents without power across the Korean Peninsula after it spread swaths of heavy rain and damaging winds gusts.

At least seven deaths were blamed on the storm in South Korea, according to the BBC. These seven deaths occurred when an underground parking garage was inundated with floodwaters. Two others trapped in the garage were rescued after clinging to ceiling pipes for more than 12 hours.

Officials said storm preparations helped minimize the overall death toll, The Associated Press reported. Hinnamnor has been recorded in the history books as the eighth-strongest typhoon to impact South Korea.

Hinnamnor, which peaked as a powerful super typhoon and roamed the western Pacific since late August, was downgraded to a tropical rainstorm as it lost strength Tuesday. Portions of southern Japan were also slammed with flooding rainfall and powerful winds early this week as the storm pushed from the East China Sea into the Sea of Japan.

Tuesday night, the storm continued to lose wind intensity as it moved north-northeastward into far eastern Russia.

Before it struck South Korea and ultimately transitioned into a tropical rainstorm, AccuWeather's Enhanced RealVue™ satellite captured Typhoon Hinnamnor as it churned in the East China Sea on Monday, Sept. 5, 2022. (AccuWeather)

Damage was caused due to the flooding early in the week as a holiday resort building was washed away in Nam-gu, Pohang, South Korea. In Yongheung-dong, Pohang, South Korea, a landslide was captured behind a local middle school. Numerous photos of broken street lights surfaced on social media, along with downed trees and power lines.

Firefighters responded to a fire that broke out at a POSCO steel plant in Pohang, reporting that at least three facilities were damaged. No casualties were reported from the fire on Tuesday.

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Around 4,500 residents were forced to evacuate their homes prior to Hinnamnor's arrival. By Tuesday afternoon, local time, roughly 3,200 people were able to return to their homes. Over 80 homes and businesses were flooded or destroyed, the AP reported. Over 600 schools chose to close for the day or convert to online classes as the storm moved across the Korean peninsula.

As the calendar flipped from August to September, Hinnamnor carried the title of super typhoon, the first storm to do so this year. In fact, at its peak strength, Hinnamnor was the strongest storm of the season in the basin and the strongest tropical cyclone anywhere on Earth so far this year, according to AccuWeather Lead International Forecaster Jason Nicholls.

A view shows a collapsed building after Typhoon Hinnamnor made landfall in Pohang, South Korea, September 6, 2022. Yonhap via REUTERS

Jeju Island, South Korea's largest island, endured some of the heaviest of Hinnamnor's torrential rainfall, recording a whopping 37.3 inches (948 mm) of rainfall from Sunday, September 4th, to Tuesday, September 6th.

Pohang, a city in far southeast South Korea, has recorded 13.5 inches (342 mm) of rainfall from Hinnamnor so far Tuesday. To the south of Pohang in Gyeongju, South Korea, roughly 8.4 inches (212 mm) of rainfall has been recorded so far.

Ahead of Hinnamnor's arrival, South Korean officials were hard at work putting proactive safety measures in place.

On Monday, about 370 flights were grounded, 100 ferry services were docked and more than 66,000 fishing boats were ordered to return to port, according to the AP. In addition, hundreds of roads and bridges were proactively closed, largely across southern portions of the Korean Peninsula and Jeju Island.

People walk in the rain as Typhoon Hinnamnor moves toward the Korean Peninsula in Seoul, South Korea, Monday, Sept. 5, 2022. Hundreds of flights were grounded and more than 200 people evacuated in South Korea on Monday as Typhoon Hinnamnor approached the country's southern region. (AP Photo/Lee Jin-man)

From Sunday to Monday, more than 24 inches (600 mm) of rain had already fallen in central Jeju, according to the AP. On Tuesday, local time, reports of the first fatality came from the eastern port city of Pohang when a woman in her 70s was swept away in floodwaters, according to Al Jazzera. On Monday, nearly a dozen buildings were flooded on Jeju while hundreds were forced to evacuate in Busan, South Korea's second-largest city.

"Recent heavy rain has fallen across North Korea and South Korea, and additional heavy rainfall from this event could lead to life-threatening and historic flooding in parts of these regions," Nicolls cautioned.

Forecasters say Hinnamnor is likely the strongest storm to slam South Korea since the potent 2020 season. September of 2020 dealt back-to-back blows to the country when Typhoon Maysak struck near Busan on Sept. 3 and Typhoon Haishen struck Ulsan, South Korea, just four days later, according to Nicholls.

Due to the historic flooding rainfall, powerful winds and dangerous seas, Hinnamnor was a 4 on the AccuWeather RealImpact™ Scale for Tropical Cyclones in South Korea.

Although the storm brought devastating impacts to South Korea, the typhoon's time over land was rather short-lived. Reports concluded that Hinnemnor made landfall around 5 a.m. Tuesday morning and shot out to sea once again by 7:10 a.m. Tuesday, gradually losing wind intensity as it entered a region of increasing wind shear and lower sea surface temperatures.

Hinnamnor will pick up forward motion from Wednesday into Thursday and track briskly northward across far eastern Russia.

"From Wednesday to Thursday, the feature will quickly track over portions of far eastern Russia and the Sea of Okhotsk as it takes on extratropical characteristics," Smithmyer said.

Still, Hinnamnor is forecast to bring a large swath of 4-8 inches (100-200 mm) of rain to the Primorsky Krai, Khabarovsk Krai and Sakhalin Oblast regions of eastern Russia on Wednesday, according to Nicholls. Rainfall of this magnitude can be enough to trigger flooding issues across these regions.

Hinnamnor is expected to continue shifting northeastward as a tropical rainstorm late this week before dissipating over far eastern Russia.

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