Can a peculiar tornado be accurately predicted?
CCB, Beijing, May 17 According to a report by the Voice of China "News Hyperlink" of China Central Radio and Television, recently, tornado disasters occurred in Suzhou and Wuhan, causing personal injury and property damage.
At around 19:00 on May 14, parts of Shengze Town, Wujiang District, Suzhou City were hit by a tornado. As of 5 am on the 15th, the disaster caused 4 people dead and 149 injured; 84 households were damaged, and the damaged area was 1,500. Square meters; 17 enterprises were damaged, and the damaged area was 13,000 square meters.
On the evening of May 14, a tornado broke out in Xishan, Caidian District, Wuhan City, and Junshan District, Wuhan Economic and Technological Development Zone.
As of 12:00 noon on May 15th, a total of 8 people were killed, 230 injured, 3568 were affected, 1197 people were relocated in emergency, 86 houses of 28 collapsed houses, and 400 houses of 130 houses were seriously damaged.
After the tornado, there was chaos everywhere, and a local person in Wuhan said that the windows and roofs were blown away.
Tornadoes come fast and go fast, how did they form?
Can it be forecasted?
How does a tornado form? What are the necessary conditions and accidental factors?
A tornado is a small-scale air vortex produced under strong unstable weather conditions.
According to Zhang Tao, chief forecaster of the Central Meteorological Observatory, the mother body of a tornado is a severe convective storm.
When the wind has different wind force and wind direction at different horizontal positions and different vertical levels, a difference in wind is formed. This phenomenon is called wind shear.
In this case, some rotating vortices will appear, just like the vortices caused by different flow speeds in a river.
When a strong convective storm occurs, various vortices are particularly prone to appear, which are not necessarily upright, but may be horizontal.
Since the ground wind is close to zero, the higher the wind goes up, the greater the wind will cause the horizontal vortex to stand up in some cases, thus forming a tornado.
Strong convective weather is an important background for tornadoes, but their own generation also requires certain conditions, such as unstable atmosphere, abundant water vapor, and flat ground.
Zhang Tao said that even if the above necessary conditions are met, it does not mean that a tornado will occur. The probability of occurrence is much less than the probability of non-occurrence. There are many accidental factors. Generally speaking, probability itself is the biggest accidental factor.
Can we forecast tornadoes? What are the difficulties?
At present, we can forecast the weather background prone to tornadoes more reliably, such as strong convective backgrounds, or even strong convective backgrounds that are conducive to the occurrence of tornadoes, including the approximate area and time, and can even forecast many days in advance.
However, for the forecast of specific individual tornadoes, the current ideal situation can only be a few minutes to ten minutes in advance, which also depends on the strength of the tornado that eventually occurs and its distance from the radar.
Zhang Tao explained that the forecast is essentially a forecast of tornadoes that have occurred and will occur. Based on the signal that the tornado has occurred or is about to appear, it sends out early warnings for places that it has not yet affected.
Since the individual life of a tornado is extremely short, from the point of view of time, it belongs to the minute level; from the point of view, it belongs to the ten-meter level and the one-hundred-meter level. Therefore, we cannot accurately predict its time, location and intensity before the tornado actually occurs. The difficulty is that its time, space and scale have exceeded the current capabilities of meteorological monitoring and simulation.
Can ordinary people predict the trajectory of a tornado?
The path of a tornado can be judged by common sense. Zhang Tao said that under normal circumstances, a tornado walks in a straight line. Although there will be a little bend, it is very rare to have a large spiral or go back.
Therefore, if ordinary people do not have professional knowledge, although there will be some impact, they can still predict through common sense.
However, to make predictions, a good vision is necessary.
This depends on three aspects: first, the matrix of the tornado is a relatively isolated supercell, covering a range of about tens of kilometers; second, the surrounding area of the tornado has sunlight penetrating in and has good light; third, the surrounding clouds The bottom is higher and the tornado can be seen from farther away.
Will extreme weather continue in the future?
In addition to tornadoes, there have been 13 consecutive days of hail in Guizhou recently. Around the evening of the 15th, Yueyang, Hunan encountered strong convective weather such as thunderstorms, strong winds, hail, and short-term heavy precipitation.
Earlier, northern my country was hit by sandstorms.
There have been a lot of extreme weather this year, but there will be more in the future.
Zhang Tao said that from a climate perspective, my country's overall strong convective weather will occur more frequently in the future, and the area affected will become wider and wider.
Because with the onset of the South China Sea monsoon and the increase in solar radiation, water vapor will become more and more abundant.
Specifically, after entering late May and June, the frequency of occurrence in my country's Jianghuanghuai, North China, and Northeast China will gradually increase.
Reporter: Liu Hejia