From November 26 to December 1, the strongest cold wave weather since the beginning of winter this year, the Central Meteorological Observatory issued the highest level of cold wave orange warning. In this cold wave, the cooling and heating masses converged on a large scale in the south of the mainland, setting off a wide range of rain and snow - monitoring data from the Central Meteorological Observatory pointed out that many provincial capitals/municipalities in the south of the mainland ushered in the first snow of this winter. For example, Hangzhou, Zhejiang, once appeared at the level of blizzard.
First, Greenland's powerful high pressure will appear
In late November, with the circulation oscillation, the powerful Arctic vortex continued to hover in Siberia, accumulating a large number of powerful cold air masses, which eventually moved south, sweeping most of the continent from west to east, triggering the strongest cold wave weather process on the continent since the beginning of winter this year. The lucky thing in the misfortune is: the blocking high pressure on the east side of the Arctic vortex is not strong, the arctic vortex is not particularly deep in the south, and the most powerful power of the cold source does not go south in the central and eastern parts of the continent, otherwise the impact will be more severe.
Of course, the circulation oscillations in the northern hemisphere are not over - the supercomputer IWR index collection forecast shows that the weather situation in the North Atlantic-Greenland line is about to begin to oscillate violently, and the index (IWR) will quickly exceed 3, which means that the extremely strong blocking high pressure in the region is about to appear. Seraphine Hauser, Ph.D. of Atmospheric Sciences, pointed out that looking back over the past 40 years, this has rarely happened, and even the blocking high pressure may be stronger than expected.
Second, is it a precursor to the great cold wave in Europe?
The latest forecast of European supercomputers also points to the existence of a strong blocking high pressure - starting around December 6, the westerly wind belt over the North Atlantic-Greenland shakes violently, and the strong blocking high pressure develops rapidly, and by December 7, the strong blocking high pressure will fully cover Greenland, and even develop northward, deep into the Arctic Circle.
What does such a powerful blocking high voltage mean? When a strong blocking high pressure forms in the westerly wind belt, it will frequently dissipate energy, opening a corridor for the cold wave to enter the Arctic Circle from the Arctic region, thereby brewing cold waves elsewhere - such as the continent, especially the upper Ural Mountains, there is a strong blocking high pressure, Siberia is prone to accumulate cold air masses, thus making the continent cold wave possible. Greenland's strong blocking high pressure will pour cold air from the Arctic Circle into Europe, and many forecasts have pointed out that after the emergence of strong blocking high pressure, strong cold weather will spread to many parts of Europe.
Third, be vigilant against subsequent impacts
The westerly wind belt orbits the northern hemisphere from west to east, and whether it is North America, Europe or Asia, it is actually under the influence of the westerly wind belt. The westerly wind belt in the upper North Atlantic-European line oscillates violently, and its energy may also be frequently dissipated downstream, which has a role in promoting cold wave activity on the continent. For example, in late 2015 and early 2016, violent meridional circulation in the North Atlantic eventually produced a tyrannosaural cold wave that snowed Guangdong. Of course, the specific situation still needs to be carefully observed, and there are still great variables in how to develop in the future.