Meteorological experts said that this year's severe convective weather is unusual. Why are severe convective weather so frequent recently?

The main characteristics of severe convective weather in my country are high incidence, multiple types, extreme intensity, and wide range of influence. Our country has entered a period of high incidence of severe convection. The types of severe convection are complex and changeable, including wind and rain, thunder and lightning, extreme winds, extreme precipitation, tornadoes, etc., mainly concentrated in the middle and lower reaches of the Yangtze River. The eastern part of southwest China to Jianghan, Huanghuai, Jiangnan, South China and other areas will be affected.

Some areas will have thunderstorm winds of level 10 or above, or hailstones with a diameter of more than 15 mm. Short-term heavy rainfall of more than 30 mm/hour, accompanied by thunderstorms, hail or tornadoes, or any of the conditions that have occurred and may continue. The rainfall in our country is still relatively large, with heavy rainfall in many places in the south. The Central Meteorological Observatory continues to issue blue rainstorm warnings. Heavy rain is expected in parts of Shanxi, Henan, Chongqing, Hubei, Anhui, Jiangsu, Shanghai, Zhejiang, Jiangxi, Hunan, Guizhou, Guangxi and other places. There were heavy rains in northeastern Hunan, southeastern Anhui, and southern Jiangsu.

Our country has entered the season of high incidence of severe convective weather. After entering mid-April, severe convective weather became significantly more severe, and the extremes became significantly stronger. The impact range of strong convective weather in different periods is different. This process is a mixed severe convective weather process, accompanied by widespread thunder and lightning and widespread short-duration heavy rainfall. In most areas, there may be hourly rainfall of 20 to 50 mm, strong winds of magnitude 7 to 10, and localized hail. A tornado is a small-scale air vortex produced under strong and unstable weather conditions. The central wind speed can reach 100~200m/s. The diameter of the lower part of a tornado is generally between a few meters and several hundred meters, and a particularly large tornado can reach 1 kilometer.

After a tornado forms, it usually lasts from ten minutes to several hours. The attack range is small, but the damage is great. Due to the obvious strengthening of the warm and humid air flow in the southwest, which brings abundant water vapor and heat, the atmosphere has become unstable, with upper cold and warm lower. Coupled with the influence of cold air from north to south, the plateau trough moves eastward, which can easily trigger strong convection. The occurrence of the weather prompted strong convective weather to move from northwest to southeast on a large scale. Such conditions are formed over a large area. Convection will be triggered once the cold air from the north moves southward or is triggered by terrain factors. As the cold air moves southward, strong convective weather will occur in many places from northwest to southeast. The same goes for frequent strong convection.