Record-breaking Typhoon Hinnamnor, Critical Phase on 5th-6th... Over 400mm Rain Expected in Central Regions

Strong Rain Cloud Bands Affect Central Region Due to Pressure Trough
600mm in Jeju Mountains, Over 400mm in Northern Gyeonggi, Gangwon Yeongseo, and Southern Coast
Rain Cloud Bands from Pressure Trough and Typhoon Converge on Night of 5th
Strong Winds Impact Jeju Morning of 5th, Southern Coast Afternoon of 5th, Southern Region Morning of 6th
Storm Surge Warning Possible for Coastal Areas, Waves Up to 10m High

[Image source=Yonhap News]

[Asia Economy Reporter Han Jinju] Typhoon Hinnamnor No. 11 is expected to strengthen as it approaches Seogwipo by the 5th and move northward toward the Korean Peninsula. Even in the central regions such as the Seoul metropolitan area, which are relatively far from the strong wind radius, more than 400mm of heavy rain is expected from the night of the 5th to the 6th due to the influence of a pressure trough. Coastal areas should also be cautious of storm surges.

On the 4th, the Korea Meteorological Administration (KMA) held a briefing and stated that Typhoon Hinnamnor will continue to develop as it moves northward and will maintain a very strong intensity. Forecaster Lee Kwang-yeon explained, "Hinnamnor will maintain its 'very strong' intensity as it approaches the Korean Peninsula, interacting with the ground and passing over cold water areas, losing energy after bringing rain. The Tibetan high pressure system to the west remains strong, and the North Pacific high pressure has somewhat contracted, opening a path for the typhoon to move northward. Additionally, warm and humid water vapor from the Indian Ocean and the South China Sea is supplied, supporting redevelopment."

Currently, Typhoon Hinnamnor is moving northward while passing 320km northeast of Taipei, Taiwan, with a central pressure of 940hPa, maximum wind speed of 47m/s, and a strong wind radius of 430km. Around 9 PM today, it will pass approximately 670km south-southwest of Seogwipo and approach about 460km south-southwest of Seogwipo on the 5th. At this time, the central pressure is expected to be 920hPa, and the maximum instantaneous wind speed is expected to reach 54m/s, making it the strongest. It is forecasted to make landfall near 20km north-northwest of Busan at 9 AM on the 6th, with a central pressure of 950hPa and a maximum instantaneous wind speed of 43m/s.

The KMA announced that by the 6th, mountainous areas of Jeju Island will receive over 600mm of rain, and northern Gyeonggi, northern Gangwon Yeongseo, southern coastal areas, eastern coastal areas of Gyeongsang, Jeju Island, areas near Jirisan, and Ulleungdo and Dokdo will receive more than 400mm of heavy rain. Expected rainfall in most other regions nationwide is between 100 and 300mm.

The period of intensifying rainfall is from the 5th to the 6th. On the 4th, the Seoul metropolitan area and Jeju Island will experience rainfall of 20 to 30mm per hour. From the 5th, hourly rainfall of 50 to 100mm is expected in the Seoul metropolitan area, central and northern Gangwon Yeongseo, and northern Chungnam, with nationwide hourly rainfall of 50 to 100mm expected on the 6th.

Heavy rain will fall not only in the southern regions directly affected by the typhoon but also in the central regions, with totals reaching up to 400mm. This is due to the influence of a pressure trough developing south of Mongolia and flowing in from the northwest, where cold and dry air converges with warm and humid water vapor moving northward from the south, developing strong rain cloud bands. The collision point of these two different air masses is the central region, where the rain cloud bands develop very high and strong, resulting in very heavy and intense rainfall. Especially in the central region, heavy rain is expected to be concentrated from the night of the 5th to the morning of the 6th, when the cloud bands from the typhoon meet.

Forecaster Lee said, "The central region and others will experience heavy rain due to the convergence zone, while the southern region will be greatly affected by the typhoon itself. The pressure trough and the cloud bands associated with the typhoon are expected to merge from the 5th to the early part of the 6th, causing widespread heavy rain nationwide. This is not just a large amount of rain but also accompanied by strong winds."

From the night of the 5th to the 6th, when the typhoon approaches, very strong winds that make it difficult to maintain balance will blow, so going outside should be avoided. In Jeju Island, the southern coast of Jeollanam-do, the coastal areas of Gyeongnam, and Ulleungdo and Dokdo, the maximum instantaneous wind speed is forecasted to be 40 to 60m/s between the night of the 5th and the 6th. The eastern coast of Gyeongbuk, Gangwon Yeongdong, and the western coast of Jeollanam-do will experience 30 to 40m/s, other southern regions and Chungcheong areas 20 to 30m/s, and the Seoul metropolitan area and Gangwon Yeongseo region 15 to 20m/s. Winds of 17m/s or more make walking difficult, 25m/s can uproot trees, and at 44m/s, people and large rocks can be blown away by the wind.

The strong winds are expected to be strongest starting in Jeju in the morning of the 5th, then the southern coast in the afternoon of the 5th, southern regions in the morning of the 6th, and Gyeongsang and the east coast in the afternoon of the 6th. Ulleungdo and Dokdo will continue to be affected by strong winds until the 7th.

Forecaster Lee added, "When Hinnamnor passed Okinawa, CCTV footage showed the cameras shaking violently, and the strong rain made it difficult for the CCTV to function properly due to the intense wind."

Jeju, the southern coast, Ulleungdo, and Dokdo must also be thoroughly prepared for storm surges. Storm surge warnings are expected to be issued mainly during high tide periods from the 5th to the 6th. During the period when sea levels rise on the 5th and 6th, waves as high as 10 meters are expected near the typhoon's path.

Forecaster Lee urged, "The low pressure at the typhoon's center raises the sea level, and when this coincides with high waves, it can cause even higher water levels, leading to coastal flooding and significant damage in low-lying coastal areas, so prior preparation is necessary."

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