The city of Zhengzhou in central China is facing devastating floods, a result of a collision between air masses from Typhoon In-Fa and a high-pressure area in the Pacific Ocean.
Typhoon In-Fa, in conjunction with the subtropical high-pressure area in the northwest Pacific, has created a moisture-laden air mass directed towards Henan Province, Chen Tao, director of the National Meteorological Center, stated on April 21.
Residents wade through floodwaters in Zhengzhou. (Photo: Reuters).
According to the meteorological bureau of Henan Province, the phenomenon is exacerbated by Zhengzhou’s topography. The city is located on the banks of the Yellow River, an area that has historically experienced severe flooding. It is surrounded by the Taihang and Funiu mountain ranges, which cause moist air to rise, forming clouds and increasing rainfall. This week’s flooding has resulted in at least 25 fatalities and displaced 1.2 million people. Heavy rainfall is expected to continue for the next 24 hours.
The subtropical high-pressure area in the northwest Pacific is an atmospheric phenomenon that influences the climate in East Asia during the summer. Previously, unusual developments of this air mass have often led to flooding, drought, and extreme heat. According to Cheng, this air mass is currently shifting further north than usual, meaning Henan Province is on the edge of the high-pressure area, causing moisture in the air to accumulate, resulting in heavy rainfall.
Typhoon In-Fa, which is expected to make landfall in mainland China on July 25, is a tropical depression that formed in the Philippine Sea the previous week but intensified and became a typhoon by the evening of July 20. Other regions in China, including Shanghai, Zhejiang, and Fujian, are on the storm’s path and will experience heavy rain and strong winds for several days; however, specific conditions have caused rainfall in Zhengzhou to exceed that of any other area.
As of the afternoon of July 21, Typhoon In-Fa was located 680 km east of Taipei, moving west-northwest at a speed of 11 km/h, according to the Central Weather Bureau in Taiwan. The storm had a radius of 180 km on the morning of July 21 with maximum sustained winds of 126 km/h.
The Henan meteorological bureau predicts that heavy rain in the area will cease as Typhoon In-Fa approaches China due to the storm’s movement altering air circulation and blocking moisture sources. In-Fa is likely to move south toward the East China Sea on July 23 and make landfall two days later in Zhejiang Province to the east, according to the Shanghai meteorological bureau.
Climate change is leading to an increase in both the frequency and intensity of extreme weather events. Environmental activists warn that preparation for natural disasters is crucial. “We cannot rule out meteorological phenomena that cause disasters like torrential rain. Especially in the current situation, as the global climate changes, disaster response is extremely necessary,” emphasized Liu Junyan, head of meteorology and energy projects at the East Asia Green Peace Office in Beijing. According to Liu, cities need to improve early warning systems, predictions, and risk identification.
The Zhengzhou meteorological bureau describes the ongoing rainfall and flooding in the city as the “worst flood in 1,000 years.” However, detailed data shows that this is the worst flooding in several decades. The maximum rainfall in Zhengzhou reached 201.9 mm per hour on July 20, breaking the previous record of 198.5 mm set in 1975, according to the National Meteorological Observatory. The total rainfall of 617.8 mm recorded over the past three days in the city is the highest in 60 years.
