The Ministry of Natural Resources and Environment has reported several unusual characteristics of Typhoon Yagi, which rapidly intensified into a super typhoon and brought unprecedented damage to northern Vietnam.
The Quang Ninh Museum was devastated on September 7. Typhoon Yagi caused extensive damage to buildings, homes, and economic sectors, with estimated losses nearing 24 trillion VND. Photo: Thach Thao
MONRE detailed the forecasting, warning, and communication efforts concerning typhoons, rain, floods, and landslides related to Typhoon Yagi and its severe impacts on the northern provinces of Vietnam.
On September 3, after entering the East Sea, Typhoon Yagi quickly intensified from category 8 to category 16, reaching super typhoon status within just 48 hours.
On the night of September 6, as the typhoon moved into the waters east of the Northern Gulf of Tonkin, its strength decreased slightly to category 14, with gusts reaching category 17.
By the afternoon of September 7, Typhoon Yagi made landfall in Quang Ninh and Hai Phong, with an intensity of categories 10-12, and near the center, categories 13-14, gusting up to 16-17. By 4am on September 8, the storm had weakened into a tropical depression over the Northwestern region.
Experts have highlighted several unusual aspects of Typhoon Yagi, marking it as the strongest typhoon in the East Sea in the last 30 years. The storm intensified rapidly 0- gaining 8 categories in 24 hours - and maintained super typhoon status for an extended period, even as it approached the east of Hainan Island in China.
Typically, typhoons weaken significantly after crossing Hainan Island and entering the Gulf of Tonkin, but this did not occur with Typhoon Yagi. Its intensity remained high, at categories 12-13, as it neared the coast of Quang Ninh and Hai Phong.
Another unusual feature was the storm’s prolonged duration over land, lasting 12 hours before dissipating.
Unusual heavy rainfall
Cao Bang province was one of the first northern mountainous areas to suffer damage from Typhoon Yagi’s aftermath. Photo: Hoang Ha
From September 7 to September 12, the northern region and Thanh Hoa experienced heavy rainfall, with widespread amounts between 250-450 mm, and some areas receiving over 550 mm. At 83 out of 84 measuring stations, rainfall levels were 4-6 times higher than the ten-year average for early September.
Notably, the Sa Pa station (Lao Cai) recorded 517 mm, 440% above average, while Luc Yen (Yen Bai) registered 503 mm, 461% above average.
MONRE also noted the unusual distribution of rainfall. As Typhoon Yagi weakened into a tropical depression in the northwestern region, the heaviest rainfall occurred east of the Hoang Lien Son mountain range, contrary to previous storms, which typically caused heavy rainfall on the western side.
Flooding was widespread in river basins across the Thao, Chay, Lo, and Gam rivers, with rainfall exceeding 200 mm/day in some areas and exceeding 200 mm in just two hours in parts of Yen Bai on the night of September 9.
According to MONRE, these unusual patterns were confirmed in online discussions with international experts from the Japan Regional Typhoon Center and the Chinese Meteorological Agency.
Historical river flooding
Approximately 500 meters of Bach Dang Street outside the Red River dike in Hanoi was deeply flooded on September 11. Photo: Hoang Ha
Heavy rainfall from the typhoon triggered rapid rises in river and stream water levels starting on September 8. Rivers such as the Thao, Lo, Thuong, Gam, and the lower reaches of the Red River exceeded alarm level 3 (AL3) by 3-4 meters.
The flood peak on the Thao River in Lao Cai and Yen Bai surpassed the historical peak of 1968, with water levels reaching 35.73 meters at Yen Bai on September 10, 3.73 meters above AL3.
At the Thac Ba hydroelectric dam, water levels reached a historic high, threatening dam safety. The dam’s discharge capacity of 3,230 m³/s was exceeded when flows peaked at 5,620 m³/s on September 10, surpassing its design limits by 74%.
In Hanoi, the Red River recorded its highest water levels in 20 years, with widespread flooding across 20 out of 25 northern provinces and cities.
Landslides
A landslide in Lang Nu village (Phuc Khanh commune, Bao Yen district, Lao Cai province) caused extensive damage. Photo: Thach Thao
Heavy rainfall also triggered widespread landslides and mudslides, causing severe damage across northern provinces, particularly in Cao Bang, Hoa Binh, Lao Cai, Yen Bai, and Quang Ninh.
In Lang Nu village (Phuc Khanh commune, Bao Yen district, Lao Cai), 37 households with 158 residents were affected by a devastating mudslide.
MONRE attributed the landslides to persistent rainfall over the past three months, which saturated the soil. For example, Lao Cai experienced 23 rainy days in August, and Yen Bai had 21 rainy days.
MONRE praised the efforts of the National Center for Hydro-Meteorological Forecasting, noting that the forecasts were timely and consistent with actual weather developments. Despite the unusual characteristics of Typhoon Yagi, the forecasting and communication efforts helped minimize the damage caused by this unprecedented storm.
Vietnamnet.vn
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