Is the area east of Shandong like an Arctic expedition? Why do cold currents and blizzards "favor" the Shandong Peninsula?

On December 20, Yantai and Weihai in Shandong Peninsula were hit by a cold front and heavy snow . The snowfall was so unique that netizens called it "like an Arctic expedition."

According to the Central Meteorological Observatory, on December 20, Shandong Peninsula experienced heavy to severe snowfall, with local heavy snowfall, with 26.3 mm of snowfall in Wendeng, Weihai, and 23.7 mm in Yantai. As of 8:00 on the 21st, the depth of snow accumulation in Wendeng and Yantai exceeded 50 cm. Meteorological experts reminded that the public should pay attention to travel safety due to heavy snowfall and long duration.

What is cold snow?

The reporter learned from the Yantai Meteorological Bureau of Shandong Province that Yantai and Weihai, as typical coastal cities, have formed a unique coastal snow city style due to heavy snowfall in winter, and are known as the "Chinese Snow Nest". The snowfall in the two cities is mainly cold current snow, accounting for more than 80% of the total number of snow days. Meteorological statistics from Yantai Laishan Airport show that the average number of cold current snow days in the area is about 39 days per year.

Cold flow snow is also called cold advection snowfall. It is caused by the fact that the Yellow Sea and Bohai Sea are warmer and more humid than the inland in winter. The strong cold air passes through the warm sea surface, is heated and humidified, and reaches the northern part of Shandong Peninsula. It is blocked by the hilly terrain in the middle of Shandong Peninsula. The air gradually becomes saturated and accumulates to the north of the mountains, forming a long period of snowfall. Therefore, this kind of snowfall is also called sea effect snowfall.

" Large-scale frontal forcing, frictional convergence and uplift of mountain terrain, and heating and humidification of the warm sea surface are the main reasons why cold current snow prefers the Shandong Peninsula ," said Lin Qufeng, chief forecaster of the Yantai Meteorological Observatory.

The ocean has a large heat capacity, and the sea surface temperature drops more slowly than the air temperature in winter. When the cold air from the south passes through the relatively warm and humid Bohai Sea, the large sea-air temperature difference causes the low-level air to warm and humidify, and stratus clouds with certain convection will form in the northern coastal areas and produce snowfall. Therefore, in winter, as long as there is a strong cold air passing through, Yantai and Weihai will snow, and the stronger the cold air, the greater the sea-air temperature difference, the more intense the sensible heat and latent heat exchange when the cold air flows through the warm sea surface, and the greater the snowfall intensity.

Cold current blizzard. Image source: Screenshot of the video by Weibo user "Guan Yun Meng Yu"

"This blizzard process is an extreme event"

Yang Chengfang, chief forecaster of the Shandong Provincial Meteorological Observatory, introduced that from the afternoon of December 15 to December 17, affected by strong cold air, cold current blizzards occurred in Weihai and Yantai areas. Among them, four meteorological stations in Muping, Wenden, Rongcheng and Weihai city had a cumulative snowfall reaching the level of heavy blizzards. Wenden had the largest snowfall, reaching 35.6 mm, which was already at the level of extremely heavy blizzards.

"This snowstorm is an extreme event," said Yang Chengfang. On December 16 alone, Wendeng received 27.5 millimeters of snow, breaking the historical record of daily snowfall in cold current snowstorms on the Shandong Peninsula. On December 17, the snow depths in Wendeng and Rongcheng reached 35 centimeters and 36 centimeters, respectively.

Yang Chengfang said that from December 20 to 22, affected by the strong cold air again, Yantai and Weihai areas experienced strong cold current snowfall again. There were heavy to severe snowfall in northern Yantai and Weihai, and local heavy snowfall, especially in Weihai. The cumulative snowfall may exceed 35 mm, and the snow depth will exceed 40 cm.

Yang Chengfang said that due to the short interval between the two heavy snowfalls, low temperatures, and large snow depth, the snow will not melt for a long time, which will have an adverse impact on the urban operations, transportation, and energy supply of the two places.

Planning and production

Source: China National Radio

Editor: Yinuo