According to the meteorological department, there are 66 automatic weather stations in Nantong with the maximum wind force exceeding 10, including 22 stations with 11 levels, 7 stations with 12 levels, 4 stations with 13 levels (39.0m/s in Haimen Baochang Town, 38.2 M / s in Haimen Dongzaogang, 37.9 M / s in Tongzhou huanben farm, 37.7 M / s in Qidong Dongyuan Beach), and 1 station with 14 levels (45.4m/s in Tongzhou Bay Sanyou group). In addition, hailstones with a diameter of 1-3cm occurred in Haian Chengdong Town, Dagong Town, Tongzhou Shizong Town, Rudong Yangguang Island, etc.
In the evening of April 30, strong convective weather such as thunderstorm, gale and hail occurred in Nantong City, with the maximum wind force reaching 14. Photo by police
On the afternoon of April 30, Nantong and its surrounding areas were still sunny, and the temperature rose to 30 degrees Celsius. Why did it suddenly turn into extreme disaster weather? Who is the culprit behind it? The reporter interviewed Professor Wang Lijuan of Nanjing University of information engineering.
The word "cold vortex" is not strange. Every year, at the turn of spring and summer, cold vortex begins to appear frequently in the weather forecast, and makes trouble for people from time to time.
Generally, we call the northeast cold vortex system which appears in Northeast China and lasts for more than three days. It's like a rotating column of cold air, falling to the ground from an altitude of 5000 meters. Driven by the northerly wind, it goes all the way south from Northeast China, Inner Mongolia and other regions, bringing cold air to the south.
In addition, the Arctic region is also rich in cold eddies. In April this year, an Arctic cold vortex directly attacked Xinjiang, causing cooling and snowfall in some areas.
In terms of synoptic scale, it is an important regional precipitation type that cold vortex can induce extratropical cyclone and produce regional precipitation in the early stage of its formation.
Why is lengwo so hot tempered
Cold vortex is a kind of cold vortex extending from the middle and upper troposphere to the lower troposphere. The properties of air mass are relatively uniform. Without the cooperation of other systems, it will not bring large-scale heavy rainfall.
Photo source: news broadcast
Recently, the weather along the Yangtze River in Jiangsu Province is fine. Under the sun's irradiation, the ground temperature rises rapidly. Controlled by the low-pressure system, a large amount of hot air accumulates and rises here. It happens to encounter the cold air behind the cold vortex going south. At this time, the area along the Yangtze River in Jiangsu Province is in an unstable state of upper cold and lower warm.
Every summer, there are many fierce battles between the northeast cold vortex and the summer monsoon, subtropical high, etc., which make the northeast part of China present the situation of frequent heavy rainfall. According to statistics, 70% of the low temperature periods in summer in Northeast China are caused by cold vortex, and nearly 40% of the cold vortex in Northeast China can produce continuous rainy weather.
Nantong is the most injured in the gale
Affected by the northeast cold vortex this time, there are obvious strong winds in areas along the Yangtze River from Anhui to Jiangsu, but it has caused great loss of life and property in Nantong, which many people can't understand.
In addition, generally speaking, the sea wind is strong, while the land wind is small. Nantong is at the intersection of the river and the sea. The convergence of wind speeds strengthens the uplift conditions, which is conducive to the generation of strong convection.
A few years ago, a serious tornado disaster occurred in Yancheng area of Jiangsu Province, causing a large number of casualties, not far from Nantong, only a hundred kilometers. So are tornadoes and thunderstorms caused by cold eddies the same thing?