From this weekend to the beginning of next week (December 12-14), a large-scale cold wave will affect the central and eastern regions of my country, and most areas will experience the coldest weather since the beginning of winter. For this reason, the Central Meteorological Observatory December 11 The first cold wave blue warning of this winter was issued at 18:00 on the same day.
It is expected that from 08:00 on December 12 to 08:00 on December 15, the eastern part of Northwest China, the central and western parts of Inner Mongolia, the western part of North China, the eastern part of Northeast China, most of Huanghuai, Jianghan, the western Jianghuai, the central and western Jiangnan, the eastern southwestern region, and South China Most parts of the central and western regions will drop by 6 to 8°C successively. Among them, some areas in northern Shaanxi, western Inner Mongolia, southwestern Hunan, southeastern Guizhou, and northwest Guangxi will drop by 10°C; the lowest temperature after cooling is 0°C line Press south to the south of Guizhou to the northwest of Zhejiang.
In addition, there are northerly winds of magnitude 4 to 6 and gusts of 7 to 8 in the north, northerly winds of magnitude 4 to 5 in the south, 6 to 7 gusts on rivers and lakes, and 6 to 8 and 9 gusts in the eastern sea area. Northerly wind.
What is a cold wave?
How to define the warning level?
According to Shi Yan, a meteorological analyst at China Weather Network, not every cold air process can be called a cold wave.
Cold wave refers to a large-scale invasion of strong cold air from polar regions or high latitudes southward to middle and low latitudes, and the daily minimum temperature of the affected areas drops by 8°C and above within 24 hours, or drops by 10°C and above within 48 hours, or Only when the temperature drops by 12°C and above within 72 hours, and the daily minimum temperature drops to 4°C or below, can it be regarded as a cold wave.
What is driving the strong cold air southward?
In winter, 95% of the cold air passes through the central part of Siberia, where it accumulates and strengthens. This area is known as the key cold wave area.
The temperature in Siberia at this time is often below -20°C. The low temperature greatly increases the density of the atmosphere, and the air continues to shrink and sink, increasing the air pressure, thus forming a powerful, deep and broad cold high-pressure air mass.
This cold high-pressure air mass is like a "refrigerator" to receive the cold air in. When the cold high-pressure pressure increases to a certain level, the cold air will violently rush to the lower latitude area because of the "not fit", forming a cold wave.
The level of cold wave warning depends on its possible impact. There are three levels from low to high, namely blue, yellow and orange warnings.
The blue warning means that the daily average temperature or daily minimum temperature in most areas of 4 or more provinces (regions, cities) is expected to drop by more than 8 ℃ in the next 48 hours, accompanied by strong winds of 4 to 5 and above. In winter, the lowest temperature in the middle and lower reaches of the Yangtze River (Jianghuai area in spring and autumn) fell below 4℃.
Cold wave weather affects big defense knowledge to understand
The cold wave weather has a wide range of influence and complex rain and snow phases. The temperature of 0℃ will be located near the middle and lower reaches of the Yangtze River, and most of the central and eastern regions will experience the coldest weather since the beginning of winter.
In addition, there are still strong winds in the north. The public needs to strengthen cold and warm measures and close doors and windows in time, stay away from billboards and other vulnerable facilities, pay attention to wind, pay attention to forecasts, and pay attention to traffic safety.
The strong winds, rain, snow, and cooling weather accompanying the cold wave can cause low visibility, icing on the ground, and snow on the road area, which pose a greater threat to road and railway traffic safety.
During this cold wave, Guizhou, Hubei, Hunan, Jiangxi and other places need to strengthen transportation and tourism safety management. Rain, snow and low temperatures will cause slippery roads, snow or road icing, and road water and icing need to be cleared in time. Prevent adverse effects on transportation, people's lives, tourism, etc.
In agriculture, cold wave weather is also prone to frost damage. All localities need to step up to increase the temperature of open-air crops and actively take measures to prevent frost and freezing.
Pastoral areas such as Inner Mongolia need to do a good job of preventing cold and warming of livestock. Jiangnan and other places need to do well in the management of greenhouse reinforcement, windproof, antifreeze, and snow removal as soon as possible, and timely do a good job in covering and storage of open vegetables.