In the north, the light gray and dark gray representing the snowfall are superimposed on the light purple and purple thick, and in the south, the dark blue and rose red representing the precipitation are covered with light green and dark green...... Open the national precipitation forecast map from January 31 to February 5, and you will see a piece of tension and color.
According to the latest news from the Central Meteorological Observatory, from January 31 to February 5, the central and eastern parts of the mainland will experience the largest and longest rain and snow weather process since this winter, and it will also be the strongest winter rain, snow and freezing weather since 2009. In response to its causes, impacts, responses and other issues of public concern, Sun Jun, chief forecaster of the Central Meteorological Observatory, gave a comprehensive interpretation.
The characteristics of the first question: wide range, long time, complex phase of rain and snow, and certain extremes
The Central Meteorological Observatory predicts that the process from January 31 to February 5 will basically cover the entire central and eastern regions, of which the eastern part of Northwest China, North China, Northeast China, and northern Huanghuai will be dominated by snowfall, and most areas in the middle and lower reaches of the Yangtze River and south will have moderate to heavy rain, and some areas will have heavy rain. However, the central and southern Huanghuai, Jianghan, western and northern Jianghuai, northwestern Hunan, and central and northern Guizhou, which are sandwiched between the two forces of rain and snow, will have complex changes in rain or sleet turning to snow.
As far as snow is concerned, in the next 6 days, there will be heavy snowfall, localized heavy snowfall or extremely heavy snowfall in parts of eastern and southern Shaanxi, southern Shanxi, southern Hebei, Henan, Shandong, Hubei, northwestern Hunan, eastern Guizhou, eastern Liaoning, and eastern Jilin, with a cumulative snowfall of up to 10 mm to 20 mm, and locally more than 30 mm. Among them, the daily precipitation or cumulative precipitation in eastern Liaoning, southern Hebei, southern Shanxi, southern Shaanxi, Shandong, Hubei, Anhui, Jiangsu, northern Jiangxi, northern Hunan, eastern and northern Chongqing will be close to or exceed the same period in history.
From the perspective of freezing rain, this will be the most freezing rain in provinces since this winter: from February 1 to 4, there will be freezing rain in southern Henan, central and western Hubei, northern Anhui, northern Jiangsu, southern Shandong, northwest Hunan, eastern Guizhou, eastern Chongqing and other places.
During this period, the southern region will also be accompanied by a wide range of thunder and lightning weather.
The second question is the cause: the north and south branch troughs echo each other, opening the channel for the warm and humid airflow to the north
One of the important causes of this rain, snow and freezing weather is the superposition of the north and south branch troughs, which opens a "green channel" for the warm and humid airflow to move northward.
In the northern hemisphere winter, the mid-latitude westerly trough is divided into two branches when passing over the Tibetan Plateau, and the westerly trough on the northern westerly jet is referred to as the "northern branch trough", while the westerly trough on the southern westerly jet is referred to as the "southern branch trough". When the two troughs coincide and superimpose during the eastward movement, a deep low-pressure trough extending from high latitudes to middle and low latitudes will form in the central and eastern parts of the continent, and the southwest warm and humid airflow can take advantage of the northward trend.
However, there is no strong enough cold air in the north to resist - the weak cold air from the south from January 31 to February 1 can only travel to the middle and lower reaches of the Yangtze River at most.
As a result, from January 31 to February 5, a clear water vapor "artery" runs through the central and eastern parts of the continent on the weather map, continuously transporting warm and humid airflows, forming snowfall in colder areas and rainfall in warmer areas.
The situation in the Jianghuai region is more complicated. It is the place where cold and warm air meet, and the temperature of the south and west sides of the Jianghuai cyclone is different from the north and east sides, which aggravates the complexity and intensity of the phase transition of rain and snow.
It is worth mentioning that this widespread freezing rain is also the result of the superimposed effects of warm and humid airflow and cold air. In the area from Huai to the northwest of Hunan and the eastern part of Guizhou, the ground temperature dropped below 0°C due to the infiltration of weak cold air, but at an altitude of 700 hPa, the southwest warm and humid airflow was still controlled, and the temperature was above 0°C, which also caused the ice crystals in the upper air to melt into rain and then touch the ground into ice when they fell.
Three questions about the impact: Large-scale rain, snow and ice are superimposed on the peak of returning home, so it is necessary to be vigilant against risks and strengthen responses
This year is expected to be the "hottest" Spring Festival in history - according to the Ministry of Transport, the cross-regional flow of people across the country is expected to reach 9 billion during this year's Spring Festival, a record high.
During the Spring Festival, there was a wide range of rain, snow and freezing weather, which was impressive in the early 2008 low temperature rain and snow freezing disaster in the south, and the "overlord" cold wave in early 2016.
The duration, low temperature intensity, and freezing range of this process are not as good as the low temperature rain and snow freezing process in the south in early 2008, and the cold degree is not as good as the "overlord level" in early 2016 The cold wave is not even as good as the cold wave process from January 21 to 23 in the past; the snowfall scope and intensity in the south of the Yangtze River are also weaker than the process from January 21 to 22 this year, but the overall location of the snowfall and freezing area in this process is northerly, and the rainfall in the middle and lower reaches of the Yangtze River and the south is obvious, and its power should not be underestimated: the rain and snow impact period overlaps with the peak of returning home, and the serious impact areas are also mostly in the central and eastern transportation hub provinces; the impact of freezing rain is large, and the impact on highways, Railway operation and flight take-off and landing are quite harmful, and severe convective weather such as lightning is also catastrophic.
Meteorological experts suggested that all localities should make various emergency preparations in advance, strengthen the management of traffic safety and urban operation, and remind the public to pay close attention to the forecast and early warning information issued by the meteorological departments and make reasonable arrangements for their travel plans; and that the relevant departments in southern Henan, Hubei, northern Anhui, central and northern Hunan, and eastern Guizhou should do a good job in inspecting electric power and telecommunications facilities. Jiangnan, South China and other places should pay attention to preventing geological disasters that may be caused by continuous rainfall and local heavy rainfall, and need to do a good job in lightning protection.
After February 7, the north-south branch trough will move eastward to the coastal areas of the mainland, and the weather will become sunny in the northern part of the Yangtze River and most areas north of it, but there may still be a certain degree of weak rain and snow in the northern region.
On the way to the Spring Festival, there is "the strongest winter since 2009" rain, snow and freezing weather, you need to know this↓↓↓
Encounter snowfall
On the national precipitation forecast map, keep an eye out for the gray patches that represent the likelihood of rain and snow. Light grey indicates 0-2.5 mm of snowfall, which is usually not too much to worry about, darker grey means 2.5-5 mm of snowfall, and you need to be vigilant that the highway may be closed, while darker grey means 5 to 10 mm of snowfall, and heavier snowfall may lead to highway closures, as rain and snow can make the road slippery and even icy, which can easily cause traffic accidents such as vehicle skiding and rear-end collisions.
If you encounter sleet or rain turning to snow on the road, then the trouble is even greater. Especially in these days, the temperature at night in most parts of the country is below 0°C, and the rain will freeze into ice at low temperatures, which brings great trouble to traffic.
Freezing rain
Whether it's on a tree leaf, a car or a road, any surface with a temperature below 0°C can be covered with a layer of ice when affected by freezing rain. In freezing rain, the roads become slippery like ice rinks, and thick layers of ice accumulate on the surface of power lines. Under the blowing of the wind, the wires swing back and forth, causing the power towers to collapse or trip and lose power. Freezing rain can also adversely affect modes of transport such as roads, railways and airways. It can cause icy road surfaces, making it more difficult and dangerous for vehicles to drive, and potentially causing traffic jams or accidents. Ice can also appear on railway tracks, affecting the safe operation of trains. For air transport, freezing rain can make it difficult for aircraft to take off and land, increasing flight risks. Therefore, in freezing rain, the transportation sector needs to take corresponding measures to ensure safety.
Freezing rain is formed when supercooled water droplets (liquid) fall from the sky and freeze into ice (solid) on the surface of the earth or other objects. In the air, when the temperature is below freezing, tiny cloud droplets or raindrops, water remains in liquid (water) form. In the clouds, supercooled water is ubiquitous. When the temperature is high, the supercooled water is high in the air and cannot reach the ground, so it cannot form freezing rain. When the temperature is too low, snowflakes or ice crystals are abundant, and supercooled water freezes onto the snowflakes or ice crystals during the fall, and it is not easy to form freezing rain on the ground. Therefore, the forecast of freezing rain requires accurate forecasting of the humidity, air temperature and surface temperature of the entire layer, so it is very difficult.
Low temperature, rain and snow, strong winds, freezing rain and other weather may bring some trouble to travel, but it can't stop the pace of going home
Author: Ye Yihong, Xu Nenyu
Editor: Liberal Arts, Wang Suqin, Yan Hong, Luan Fei Release: Guo Manru Review: Duan Haoshu