From January 31 to February 5, the strongest rain, snow, and freezing weather since 2009 swept across central and eastern my country. The Central Meteorological Observatory continued to issue warnings for snow, ice, and strong winds. At the peak time of travel back home before the Spring Festival, widespread rain, snow, and freezing weather had a great impact on Spring Festival transportation.
According to statistics from the China Meteorological Administration, since January 31, widespread rain, snow, and freezing weather that lasted for nearly 6 days affected the central and eastern regions, affecting 18 provinces (autonomous regions and municipalities), affecting a land area of more than 2.5 million square kilometers.
"This rain, snow and freezing weather process has the characteristics of long duration, wide range of rain and snow, complex precipitation phase, many provinces with freezing rain, strong rain and snow intensity, certain extreme local precipitation, and deep snow accumulation during the process." Xu Jun, chief forecaster of the Central Meteorological Observatory, said.
Zhao Junhu, chief on duty at the National Climate Center, told reporters from China Youth Daily and China Youth Daily that historically, large-scale, long-lasting freezing rain and snow weather in our country is rare.
"The most impressive one was in early 2008, when southern my country suffered from freezing rain, snow and low-temperature disasters that were rare in history. It was wide-ranging, intense, long-lasting, and had severe impacts. It was rare in history." Zhao Junhu said that the most recent one was in January 2022. From January to February, many obvious rain and snow weather processes occurred in southern my country, but the scope was small and the intensity was weak, and the impact was not as great as in 2008.
According to the latest monitoring from the National Climate Center, the moderate-intensity El Niño event that began in May 2023 peaked in December and is now entering a recession. This event is expected to last until the early spring of 2024. According to statistics, the El Niño event has the most significant impact on the weather and climate systems of the tropics and the southern hemisphere in the early stages of its development; during its peak development period in winter, it will affect the winter climate of the northern hemisphere.
Why did this heavy rain and snow weather occur during the "warm winter"? Zhao Junhu explained that in the winter when El Niño occurs, the temperature in most parts of my country is close to normal to high (some years will have warm winters), but cold air is active in phases, and the temperature in my country fluctuates greatly. On the other hand, in the winter of El Niño years, the intensity of the subtropical high in the northwest Pacific is stronger, and the water vapor conditions in central and eastern my country are better, so precipitation is likely to be higher than the same period in normal years. Therefore, the El Niño event is an important climate background for this widespread freezing rain and snow weather.
So, what is the cause of this rainy and snowy weather? Sun Jun, chief forecaster of the Central Meteorological Observatory, analyzed that one of the important causes is the superposition of the north and south branch troughs in phase, which opens a "green channel" for warm and moist airflow to move northward. In the northern hemisphere winter, the mid-latitude westerly belt is divided into two branches when passing through the Tibetan Plateau. The westerly trough that appears on the northern branch of the westerly jet stream is referred to as the "North Branch Trough", while the westerly trough that appears on the southern branch of the westerly jet stream is referred to as the "Southern Branch Trough". Branch trough".
"When the two troughs coincide and overlap during their eastward movement, a deep low-pressure trough extending from high latitudes to mid-low latitudes is formed in central and eastern my country, and the southwest warm and moist air flow takes advantage of the momentum to move northward. And the north is not strong enough. The cold air resists, causing the warm and moist airflow to be continuously transported, forming snowfall in the colder areas and rainfall in the warmer areas." Sun Jun said that the overall location of the snowfall and freezing area in this process is northerly, and the middle and lower reaches of the Yangtze River and beyond There is significant rainfall in the southern region, and its power cannot be underestimated.
What impact will this process have on the Spring Festival Transport? Liu Yanxiang, Chief Meteorological Service Officer of the Public Weather Service Center of the China Meteorological Administration, said that in terms of highway traffic, low visibility caused by rain, snow and freezing weather may reduce drivers' ability to predict road conditions; slippery roads caused by snow and ice may Causing traffic disruption or congestion. In terms of aviation, low visibility and snowy and icy runways also affected aircraft takeoffs and landings, causing flight delays.
"In terms of railways, in addition to low visibility affecting drivers' judgment of road conditions, snow and ice on the railway may cause the rails to freeze or deform. We need to be highly vigilant about the potential risk of icing at railway crossings affecting train operation. In addition, the railway signaling system and communication equipment may also be affected." Liu Yanxiang said.
As of 8:00 on February 5, during this round of weather, the maximum snow depth at 144 national meteorological observation stations in the central and eastern regions reached more than 10 centimeters, with local snow accumulation in northern Anhui, southeastern Henan, and central Hubei. The depth is close to 20 centimeters, and the snow depth in Mengcheng, Anhui Province reaches 24 centimeters. Among them, the snow depth in Qianjiang, Hubei Province reached 20 centimeters, and Huoqiu, Anhui Province reached 23 centimeters, breaking the February snow depth record in local records; the maximum snow depth in Hongze, Jiangsu and other five places exceeded the historical extreme value for the same period in February since 2009.
Xu Jun said that from February 6 to 7, widespread rain and snow weather continued in the south, with cumulative snowfall in some areas ranging from 5 to 18 millimeters, and locally exceeding 20 millimeters. There is freezing rain in parts of central and eastern Guizhou, most of Hunan, mountainous areas in northwestern Jiangxi, mountainous areas in southern Anhui, and mountainous areas in western Zhejiang.
Meteorological experts remind that there are still heavy rain, snow and freezing weather in Hubei, Hunan, Jiangxi and other places recently, and the temperature continues to be low, which is not conducive to snow and ice melting. It is recommended that the public pay close attention to the latest forecasts and warnings issued by the meteorological department and the latest road condition information issued by the transportation department before traveling, plan their trips reasonably, and prevent the adverse effects of icy roads on traffic; at the same time, do a good job in keeping warm and cold, and pay attention to the use of electricity and gas. Fire safe.
China Youth Daily·China Youth Daily reporter Qiu Chenhui Source: China Youth Daily