Experts weigh in on gale winds incident that took 3 people from their beds in China's Jiangxi

It was about 3 a.m. in Nanchang City, east China's Jiangxi Province when thunder began to roll behind thick dark clouds lit by sporadic lightning strikes.

Angry gales also roared, zigzagging through the gaps between tall buildings and pounding on the windows.

Three people asleep in their beds, one on the 11th and two on the 20th floor of an apartment building, were sucked out of their rooms and thrown to the ground. Later, their family members would awake to find their loved ones lying on the ground outside the building, lifeless.

The three were among four casualties in the strong convective weather conditions that started wreaking havoc on the city on Saturday.

Winds as potent as a category 12 hurricane, the highest measurement on the Beaufort wind scale, also toppled over 1,600 trees in a district in Nanchang City.

The way the victims died and the abruptness and power of the weather have prompted heated discussions on Chinese social media.

CGTN consulted experts in meteorology in an attempt to find some explanation.

1. What's the cause of the convective weather?

"The development of strong convective weather requires three elements: sufficient water vapor, volatility and elevation. Nanchang had all of them," Professor Meng Zhiyong, deputy head of Peking University's School of Physics, told CGTN in an interview.

The weather phenomenon is a result of intense convection, the vertical movement of heat and moisture in the atmosphere, usually from a warmer area on the ground to a cooler area above. 

Meng said the abnormally high temperatures in Nanchang in late March intensified the convection when the hot light air rose from the ground and combined with the cold air high in the sky.

Hu Xiao, chief weather analyst from Weather China, a website run by China Meteorological Administration, echoed Meng's explanation in his interview with CGTN.

"The collision between the cold air and warm air is the most basic principle in the formation of strong convective weather. In Nanchang's case, the warm and humid air near the ground and the cold air in the atmosphere formed a 'cold up and warm down' structure, which could easily lead to strong convection," he said.

Other theories about the destructive nature of the weather have also surfaced online.

A blogger named "China Weather Enthusiast," who has nearly 10 million followers on China's social media platform Weibo, cited the Venturi effect to point out that when the wind enters a narrower space, such as the space between two tall buildings, its speed increases, to explain the deadly gale that swept three people out of their rooms.

2. Is the accident normal?

Although spring is a hot season for strong convective weather, both Meng and Hu described the accident as unusual.

"Strong convective weather leading to deaths is common, but to sweep off the bed mattress with the people sleeping on it from indoors is not," Meng told CGTN.

"As far as I recall, it's a very rare case of wind blowing beds and windows down from within a building," Hu told CGTN.

3. Is the quality of the building's construction to blame for the accident?

Following the accident, some people on social media platforms, such as Douyin, have questioned the quality of the building's construction, especially the windows.

According to a video from Shanghai news magazine Xinmin Weekly widely circulated on Douyin, the building developer for the apartment where the three people died after being sucked out of their rooms was involved in a major corruption case in the province.

However, multiple media houses have reported that the developer has denied construction quality issues.

A video published by Ifeng.com, the news website of Hong Kong's Phoenix TV, shows that police are investigating the building's construction as part of the case.

4. Can we predict strong convective weather?

Yes and no.

Reports say prior to the accident, Nanchang's weather department issued a yellow alert for thunder and lightning at 10:18 p.m. on Saturday. It reportedly issued another yellow alert for gale at 11:11 p.m. and upgraded the gale alert to orange at 3 p.m. on Sunday.

However, experts acknowledge that precise prediction of the phenomenon is still a scientific puzzle.

"Strong convective weather usually takes place in a small area and it happens very fast, so it remains a challenge in the field of weather forecast," Hu told CGTN.

"Improving our observation and awareness on the formation of strong convective weather, enhancing the warning system, educating the public … That I hope will reduce the damage," Meng said.

(Cover: A view of Nanchang City, Jiangxi Province, east China, April 1, 2024. /CFP)