The climate forecast for this winter released by the China Meteorological Administration on the 4th shows that the cold air activities affecting China this winter are frequent and the forces are strong, the temperature in the central and eastern regions is generally cold, and the precipitation is generally distributed in the north and south.
As the "Year of Double La Niña", how cold will it be this winter? Will there be widespread rain, snow and ice disasters? What precautions do we need to take?
Frequent cold air activity Cold temperatures do not equal cold winter
Previously, the National Climate Center said it would form a weak to moderate-intensity La Niña event this winter. In the winter when most La Niña events reach their peak, the cold air activity affecting our country is more frequent and intense than usual. In view of the La Niña incident in the autumn and winter of 2020-2021, 2021 will be the "year of double La Niña", under the "double influence", many members of the public are concerned about whether this winter will be a cold winter?
The forecast shows that the cold air activity affecting China this winter is frequent and the force is strong, and the temperature in the central and eastern regions is generally cold. Among them, Liaoning, central Inner Mongolia, Beijing, Tianjin, Hebei, Shanxi, northern Shaanxi, northern Henan, Shandong, northern Xinjiang and other places will be 1 °C-2 °C.
Jia Xiaolong, deputy director of the National Climate Center, said that the concept of cold and cold winter is not the same. Cold refers to whether the temperature is low or high on average, but there are strict criteria for cold winter. The basic factor for determining cold winter is the average temperature of three months in winter, which is spatially divided into three levels: single station, regional and national.
Single-station cold winter refers to the average temperature distance of a single station less than or equal to -0.43 times the standard deviation; regional cold winter means that the number of cold winter stations exceeds 50% of the total number of regional stations; while the national cold winter requires the cold winter area to exceed 50% of the effective area of the country. Therefore, the criteria for judging cold winter are related to the degree and range of low temperatures.
"Cold winter is more of a comprehensive assessment and judgment of the winter climate situation, this year we expect the possibility of low temperatures is relatively large, but whether it can reach cold winter depends on the standard." Jia Xiaolong said.
In addition, the La Niña event is only one of the factors affecting China's winter climate, and the snow accumulation at the middle and high latitudes and the changes in Arctic sea ice will increase the uncertainty of the winter climate. Through the analysis of the 15 La Niña events that have occurred since 1951, there are 10 La Niña years in which the winter temperature in China is low, 5 La Niña years have high winter temperatures in China, and the most recent high temperature occurred in 2020.
Although there were four major cold waves in the previous winter, the cold wave in early January allowed the minimum temperature of many meteorological observation stations to break through or reach the historical extremes since the establishment of the station. But in March this year, the National Climate Center announced that the winter from December 1, 2020 to February 28, 2021, was a warm winter. Extreme events with abnormal temperature fluctuations are more likely to be of concern than average temperatures.
Image source: China Meteorological Administration
Intra-season cold and warm fluctuations Are more likely to occur in stages of extreme strong cooling
Forecasts show that in December 2021, except for the low temperature in the northeast and eastern Inner Mongolia, most of the rest of the country is close to the same period of the year or high. From January to February 2022, the cold air activity will be significantly stronger, and the temperature in most parts of central and eastern China may be lower than that of the same period of the year, and the possibility of a staged extreme cooling event is high. Northeast China, north China, the eastern part of the northwest region, northern Xinjiang and other places may have staged strong cooling and heavy snow precipitation processes.
Experts said that the volatility in this winter is relatively large, and it is not excluded that there will be a relatively strong cold wave event, and the impact on the north is more obvious. In the context of global warming, the climate system is more unstable, and extreme events occur more frequently and more intensely.
Starting from November 4, the cold wave will affect most of China from the northwest to the southeast, and the cooling range is generally 8 °C-10 °C, and the cooling range in some areas may exceed 16 °C. Accompanied by the "cliff-like" cooling, there are also strong winds and rain and snow weather, and the Central Meteorological Observatory continued to issue a yellow warning of cold tide on the 4th.
At the same time, the forecast shows that the eastern part of the southwest region, the western part of Jiangnan and other places may have staged low-temperature rain, snow and freezing weather. Expert analysis, and the occurrence of large-scale continuous rain and snow freezing weather in the south in 2008 is different, this year's water vapor conditions in the south are not as good as in 2008, and the possibility of large-scale, sustained low-temperature rain and snow freezing weather is small, but it is necessary to pay attention to the adverse impact of phased low-temperature rain and snow freezing weather on the power grid and transportation.
(Original title: How cold will it be this winter? Expert Answers -)
Source: Xinhua News Agency
Process Editor: tf008