Concerns over Vietnam's forecasting and assessment of Typhoon Yagi back in 2024

Typhoon Yagi (known in Vietnam as Typhoon No. 3 of 2024) is considered the most historic typhoon in Vietnam, with records set in both meteorological factors and the damages it caused in the country.

Specifically, according to the Government's report to the National Assembly on the damages and aftermath of Typhoon Yagi on October 22, 2024, Typhoon No. 3 resulted in 345 deaths and missing persons, with the total economic loss estimated at 81.703 trillion VND (equivalent to 3.2 billion USD). The provinces that suffered the most significant damages were: Quảng Ninh with 24.876 trillion VND and Hải Phòng with 12.249 trillion VND.

In this regard, Typhoon Yagi is the most economically damaging typhoon in history (the damages from Typhoon Yagi alone exceed the total damage from all natural disasters in Vietnam since 2020 until before the typhoon made landfall). It is also the deadliest typhoon in Vietnam in the 21st century.

Although it was forecasted early and with the cooperation of the people and local authorities in proactive prevention efforts, the damages were somewhat reduced. However, the typhoon’s forecasting and its impact raised many questions due to significant discrepancies compared to the forecasts and reports from international meteorological agencies, especially with the leak of a report from the Vietnam National Center for Hydro-Meteorological Forecasting (NCHMF) sent to the Northwest Pacific Typhoon Committee (ESCAP/WMO Typhoon Committee). This document, quite lengthy (30 pages), summarizes research and details about all the doubts regarding the forecasting, assessment, and reporting of Typhoon Yagi’s intensity. The document contains some technical terms that may be difficult to understand, but they can be summarized as follows:

  • The Vietnam National Center for Hydro-Meteorological Forecasting (NCHMF) forecasted and assessed the maximum intensity of Typhoon Yagi over the South China Sea as being lower than the predictions from other reputable regional meteorological agencies.
  • NCHMF also predicted that Typhoon Yagi would weaken over the Gulf of Tonkin before making landfall in Vietnam with winds at 11-12 bft. This forecast was significantly lower than the predictions from other agencies in the region.
  • During the landfall of the typhoon, NCHMF only reported once the data recorded at the Bãi Cháy station at 14 bft when the typhoon began its strongest impact at 14:00 on September 7, 2024. Subsequent reports removed this data. During this time, NCHMF reported Typhoon Yagi made landfall with winds of 12-13 bft.
  • It was not until the report and bulletin on September 21, 2024, that this data reappeared in full detail. The Bãi Cháy station recorded 45m/s (14 bft) at 13:00 on September 7, 2024, with gusts at 62m/s (17 bft). In this official bulletin, NCHMF confirmed the typhoon made landfall with winds of 13-14 bft.
  • Two months later, a report, allegedly from NCHMF, was sent to the ESCAP/WMO Typhoon Committee for presentation at the annual conference from November 19-22, 2024, in Shanghai. This report indicated that the Bãi Cháy station recorded winds of 50m/s (15 bft) at 13:21 on September 7, 2024, with gusts at 63m/s (above 17 bft). It reported the typhoon made landfall with winds of 14-15 bft. This report was later cited on Wikipedia. Even an article in the Justice Newspaper (Báo Công lý) at the end of 2024 briefly mentioned this original report.
  • After this information was leaked, the next day, another report was issued, replacing the previous one, although it was identical to the old one (even retaining the same spelling mistakes and place names). It simply adjusted the Bãi Cháy station data back to 45m/s at 13:00 on September 7, 2024, with gusts of 62m/s, and the typhoon made landfall at 13-14 bft. This updated report remained unchanged after the Typhoon Committee’s meetings.
  • When asked about the 50m/s recorded at Bãi Cháy at 13:21 in the old report, Deputy Director of NCHMF, Mr. Hoang Phuc Lam, confirmed the existence of that number but argued that it was incorrect due to the station's measurement being at an improper height and being an automatic station. The 45m/s recorded at 13:00 was from a manual synoptic station.
  • However, manual observations only occurred eight times a day at specific hours (01:00, 04:00, 07:00, 10:00, 13:00, 16:00, 19:00, and 22:00), making it difficult to accurately assess the full strength of the typhoon. In the official report on September 21, 2024, several other stations were mentioned as automatic stations at various heights, including the Phù Liễn station.
  • The data from the automatic station at Bãi Cháy was used in reports and evaluations of the intensity of many previous typhoons in the region before Typhoon Yagi but was excluded when reporting on Yagi’s intensity.
  • NCHMF had previously been known to issue inaccurate forecasts but still reported the closest possible intensity domestically, only releasing precise data at international conferences like those of the Typhoon Committee and then revising it domestically in the following year, such as in the case of Typhoon Mirinae in 2016.

It is important to note that the entire incident mentioned above has not been discussed by any mainstream media, either domestic or international (except for Báo Công lý on December 31, 2024, which briefly referenced the 50m/s and 63m/s gust data at Bãi Cháy). The excerpt from the Justice Newspaper briefly mentions the issue:

Yagi đổ bộ vào Việt Nam với sức gió vùng gần tâm bão đạt cấp 13-14 giật cấp 16-17, tại Bãi Cháy (Quảng Ninh) ghi nhận sức gió 45m/s cấp 14 giật 62m/s trên cấp 17 (tuy nhiên một báo cáo ban đầu của ngành Khí tượng thủy văn Việt Nam gửi Hội thảo lần thứ 19 của Ủy ban Bão Châu Á-Thái Bình Dương ESCAP WMO Typhoon Committee cho biết bão đổ bộ với cường độ cấp 14-15 và sức gió tại Bãi Cháy là 50m/s – cấp 15 giật 63m/s – trên cấp 17), được Chính phủ đánh giá là cơn bão mạnh nhất trong 70 năm qua trên đất liền nước ta.

(https://congly.vn/tong-ket-2024-thoi-tiet-thuy-van-viet-nam-khoc-liet-va-di-thuong-465159.html)

If you want to read the full document with related information, you can view the PDF file at this Google Drive link. (The document is in Vietnamese)