Typhoon Hinnamnor Intensity Ranks 3rd Strongest Ever...KMA Says "Preemptive Measures Reduced Damage"

Typhoon Hin Nam No's Central Pressure 955hPa at Landfall in Geoje
Third Strongest After Sara and Maemi... Rainfall Exceeds Maemi
400mm Deluge in Pohang and Gyeongju Due to Air Collision Causing Cloud Formation
From Afternoon, Areas Except Ulleungdo and Dokdo Exit Typhoon Influence Zone

Due to the impact of Typhoon Hin Nam No, part of the E-Mart store in Indeok-dong, Nam-gu, Pohang-si, Gyeongbuk, and some roads were flooded on the morning of the 6th. (Photo by Yonhap News)

[Asia Economy Reporter Han Jinju] Typhoon Hinnamnor, the 11th typhoon of the season, made landfall on the Korean Peninsula with the third highest central pressure ever recorded. Its maximum instantaneous wind speed was the eighth strongest on record.

The Korea Meteorological Administration (KMA) held an ad-hoc briefing on the 6th and announced that when Typhoon Hinnamnor was closest to Jeju at midnight, its central pressure was 945 hPa; at 4:50 AM when it made landfall in Geoje, it was 955 hPa; at 6 AM passing Busan, it was 955 hPa; and at 7:10 AM when it moved out to the sea off Ulsan, it was 960 hPa.

It was the third strongest among typhoons that recorded the lowest sea level pressure in history. In 1959, Typhoon Sarah recorded 951.5 hPa, and Typhoon Maemi recorded 954.0 hPa, with Hinnamnor following Maemi at 955 hPa. It was stronger than Typhoon Maysak (957.0 hPa). Although the central pressure was 5 hPa higher than the initially forecasted 950 hPa by KMA, it falls within the range of variability.

Forecaster Lee Kwang-yeon of KMA explained, "Hinnamnor's central pressure was 1.9 hPa higher than Maemi's and 6 hPa lower than Rusa's. The observed sea level pressure at the time it affected the Korean Peninsula was very similar to Maemi's," adding, "In terms of rainfall, it was much heavier than Maemi in 2003."

Typhoon Hinnamnor's maximum wind speed ranks eighth highest historically. The highest 10-minute average wind speed recorded was 37.4 m/s at Maemuldo, Tongyeong, Gyeongnam. Compared to past typhoons, it was weaker than Typhoon Lingling in 2019 (maximum daily wind speed of 42.1 m/s) but faster than Typhoon Helen, which made landfall in 1961 (36.7 m/s). The instantaneous maximum wind speed was observed to exceed 40 m/s in the mountainous areas of Jeju and along the southern coast.

Due to the impact of Typhoon No. 11 'Hinnamnor', heavy rain fell on the 6th, and the area around Jamsugyo Bridge in Seoul is submerged in the flooded river./Photo by Hyunmin Kim kimhyun81@

The KMA explained that the reason for the damage caused by the typhoon being less than expected was not because the typhoon was weaker than forecast, but because of the significant impact of prior preparations. Since the typhoon affected the entire country, it is difficult to say that the impact was minor. The forecaster emphasized, "The factors determining typhoon damage are not limited to the intensity of the typhoon itself but also include how well preparations were made and actions taken in advance, as well as the extent of social infrastructure. We believe that prior preparations and infrastructure had a major influence in this case."

The KMA's forecasted typhoon path was generally accurate, but the time of landfall on Jeju Island and the southern coast of Gyeongnam was about one hour earlier than initially expected. The forecaster said, "A one-hour difference corresponds to a distance of 25 to 30 km. This typhoon was a large system with a diameter of 800 km, and a 25-30 km range can be considered part of the inherent variability in nature," adding, "Since the predicted path was consistently the same and the typhoon moved northward along the forecasted route, the one-hour difference can be sufficiently explained within the margin of error or variability of the typhoon."

Typhoon Hinnamnor had a large scale with a radius of strong winds exceeding 400 km, and during its northward movement toward the Korean Peninsula, it passed over warm sea areas, undergoing a redevelopment process to reach a 'very strong' level. During this process, it absorbed a large amount of water vapor and brought very heavy rain mainly to Jeju and the southern coastal areas. At Jeju's Witseoreum, 1188 mm of rain was recorded from the 1st to 11 AM on the 6th, and Samgakbong recorded 1098.5 mm. The southern coast and Gyeongsang region received 400 to 500 mm, with most areas experiencing around 300 mm of rainfall.

Especially, as Hinnamnor passed, severe typhoon damage occurred in Pohang, Gyeongju, and Ulsan. This was due to over 400 mm of heavy rain falling from the previous night until morning. The heavy rainfall was caused by the collision of cold, dry air descending from the north and humid air from the typhoon, which strongly developed the rain bands. By 10 AM, 483.5 mm fell at Tohamsan in Gyeongju, 466.1 mm in Pohang, and 422.5 mm in Ulsan. The maximum hourly rainfall observed in Pohang was 110.5 mm, and in Gyeongju, it was 95 mm.

The forecaster explained, "The typhoon's center was located over Ulsan, and under these conditions, south-easterly winds were supplied due to the typhoon's counterclockwise circulation. Similar to the rainfall observed in the metropolitan area before the typhoon, strong linear rain bands developed due to air collision. We are currently analyzing whether the dry air weakened the typhoon's intensity."

From the afternoon of the 6th, areas excluding Ulleungdo and Dokdo will be out of the typhoon's influence zone. However, even after the typhoon moves eastward, strong northwesterly winds are expected to cause locally strong winds. The forecaster added, "Waves will rise mainly in the East Sea due to winds accompanying the typhoon, and as the waves pushed by the typhoon approach the coast, there is a high possibility of swell waves hitting the East Coast and the eastern South Sea coast from afternoon to night." As of 10 AM on the 6th, Hinnamnor was moving northeast about 70 km south of Ulleungdo and is expected to weaken to a tropical depression by 9 PM in the sea near Sapporo, Japan.

This content was produced with the assistance of AI translation services.