Typhoon Bavi May Trigger 'Venturi Effect'! Mayor Chiang Warns: Taipei Could Face Up to Category 12 Winds, Uprooting Trees

Typhoon Bavi is threatening northern Taiwan, leading Taipei City to suspend work and classes on July 11. Taipei Mayor Chiang Wan-an stated that meteorological teams predict torrential rain and strong winds on the 11th, with wind speeds in the city reaching up to Beaufort Scale 10–12. Such wind strength could uproot trees and cause signs to fly off, potentially triggering a 'venturi effect' that amplifies destructive wind power.

What is the venturi effect? Also known as the canyon effect, it occurs when airflow moves from a wide area into a narrow passage—such as valleys or between high-rise buildings. As the cross-sectional area shrinks, air cannot accumulate and is forced to accelerate, causing wind speed to surge dramatically within the passage and significantly increasing destructive force.

Chiang Wan-an posted on Facebook that, according to forecasts from the Central Weather Administration and meteorological teams, the period from the evening of the 10th through the entire day on the 11th will be the most significantly affected by Typhoon Bavi in Taipei, with both wind strength and rainfall being non-trivial.

Chiang explained that, after discussions and consensus among the four cities of Keelung, Taipei, New Taipei, and Taoyuan, Taipei City has decided to suspend work and classes on the 11th. Typhoon Bavi is one of the largest typhoons in the past 25 years in terms of its wind field. In addition to heavy rainfall, the range of strong winds is also extensive. Taipei City is taking no chances and has entered full alert mode.

Chiang mentioned that during the morning typhoon task force meeting on the 10th, he instructed the Taipei team to use the final preparation window before the arrival of wind and rain to conduct comprehensive inspections on drainage ditch clearing, tree trimming, securing of signs and advertising structures, and construction site safety.

Chiang urged the public to stay at home as winds and rain have already begun to intensify, to complete household typhoon preparations, and to monitor the latest meteorological information, calling for collective readiness.

Work and class status on July 11 across regions: - Keelung City｜Suspended - Taipei City｜Suspended - New Taipei City｜Suspended - Taoyuan City｜Suspended - Hsinchu City｜Suspended - Hsinchu County｜Suspended - Miaoli County｜Suspended - Taichung City｜Suspended - Changhua County｜Suspended - Yunlin County｜Suspended - Nantou County｜Suspended - Chiayi City｜Suspended - Chiayi County｜Suspended - Tainan City｜Suspended - Kaohsiung City｜Suspended - Pingtung County｜Suspended - Yilan County｜Suspended - Hualien County｜Suspended - Taitung County｜Normal operations - Lanyu Township, Green Island Township｜Suspended