The Taiwan Central Weather Bureau announced today (18th) that there are three tropical depressions over the Pacific Ocean namely TD20, TD21, TD22. The 20th tropical depression has intensified into Typhoon “Mitag” while the 21st tropical depression is expected to develop into “Huerjasha”. Meteorologists estimate that “Huerjasha” will strengthen to a strong typhoon or higher, bringing strong winds and heavy rains. Eastern Taiwan needs to be on high alert for heavy rainfall on the 23rd and 24th.
The Taiwan Central Weather Bureau issued a typhoon formation alert at 3:26 pm today, stating that the tropical depression (TD20) originally located near the waters of Pratas Island developed into a tropical storm at 2 pm, named Typhoon No. 17 (internationally known as MITAG, Chinese name: Mitag). It is forecasted to move towards the northwest-west direction to the sea near Guangdong, having no direct impact on Taiwan.
The Bureau posted on Facebook that September is a prime time for typhoons, being the second most active month for typhoons in a year. Long-term statistics from the Bureau (1958-2024) show that July to October are the peak period for typhoon formation. August has an average of 5.39 typhoons, followed by September with 5.04, while July and October also have an average of around 4 typhoons each. Many think that typhoons should decrease after summer vacation, but September and October remain active months for typhoons.
Associate Professor Wu Derong from the Department of Atmospheric Science at Taiwan Central University mentioned in the Meteorological Application and Outreach Foundation’s “Sky Machine Classroom” column that as of early morning on the 18th at 2 am, according to the Central Weather Bureau’s path potential prediction map, the tropical system is moving to the west of the Bashi Channel and is expected to develop into a tropical storm “Mitag”, moving towards the Pearl River Estuary and gradually turning westward. The moisture from its periphery will lead to rain potential from today to the 20th.
Wu mentioned that the European model simulation on the evening of the 22nd at 8 pm shows that “Huerjasha” is expected to enter the Bashi Channel and continue moving west. The latest American model simulation has also adjusted to be similar to the European model, forecasting its strengthening to a “moderate” level or higher, bringing strong winds and heavy rain. However, with the computer simulations being around a week long, there are scientific uncertainties regarding its future trajectory and whether it poses a greater threat. Continued observation is crucial.
Moreover, according to the European model (ECMWF) simulation on the evening of the 17th at 8 pm, an increased moisture flow from the large low-pressure circulation and tropical storm “Mitag” is expected from today to the 20th, resulting in localized rain in the eastern region and Kaohsiung. Afternoon localized short showers or thunderstorms with a tendency to expand northward daily are likely to occur, with a probability of heavy thunderstorms.
He also mentioned that by the 22nd, as “Huerjasha” approaches, Taipei and Yilan-Hualien will see rain. Despite the absence of cold air, temperatures may slightly decrease due to the rain, with other regions still remaining warm. On the 23rd and 24th, as “Huerjasha” passes through the Bashi Channel and enters the South China Sea, heavy rainfall is expected in eastern Taiwan. The severity of impact on other regions depends on the proximity to the system, requiring continuous observation.