On April 12th, the power of the previously said dry and hot air mass has begun to appear in the northern region: the temperature in North and Northeast China has risen rapidly today, Harbin ushered in the first 20 degrees of this year just after 12 o'clock, and the temperature in the Naiman Banner of Tongliao in Inner Mongolia has soared to 29 degrees, a new high this year, and even the temperature in Zhalantun at the southern end of Hulunbuir in Inner Mongolia has exceeded 20 degrees.
1. Dangerous weather expands northward
Spring is a season of revival and change. During this season, we often encounter some special weather phenomena, such as heavy rain, strong convection, hail, thunderstorms, etc. On the afternoon of April 12, the weather in the northern region was already showing signs of change: satellite images showed that although the northern part of the country was becoming more constant, clusters of strong convective clouds emerged in the eastern and western parts of Inner Mongolia, indicating that the atmospheric energy has increased sharply in the recent warming wave, and the atmosphere has begun to become less stable.
At present, the southern part of the mainland is in the pre-flood season, and under the influence of the subtropical high and the warm and humid airflow from the southwest, the temperature is high, the water vapor is more, and the atmospheric stratification is unstable, which is easy to form strong convective weather. It is expected that from 14:00 on April 12 to 08:00 on the 13th, there will be short-term heavy precipitation in parts of central, western and southeastern Chongqing, northeast Guizhou, Hunan, central and southern Jiangxi, eastern and southwestern Fujian, and northwestern Guangxi, with hourly rainfall of 20-40 mm, and locally up to more than 50 mm.
But in fact, the forecast also shows that there will be thunderstorms, strong winds or hail in northeastern Heilongjiang, central Jilin, northern Liaoning, northeastern Guizhou, southeastern Chongqing, northwest and southern Hunan, and southern Jiangxi. According to this forecast, not only will there continue to be intense weather in many places in the south, but a series of dangerous weather such as thunderstorms, strong winds, and hail will also increase in the north.
Second, a large-scale cold vortex thunderstorm in the north is accumulating!
In fact, as the westerly trough moves eastward and gradually forms a cold vortex, April 12-April 15 will bring a classic spring and summer cold vortex thunderstorm process to the northern region.
However, during this period in the north, the near-surface heat is significantly strengthened, and the cold air thrown out by the cold vortex is easy to form a vertical structure of the atmosphere that is cold at the top and warm at the bottom, which triggers thunderstorms, which marks the start of the thunderstorm season in the cold vortex in the north.
3. Authoritative forecast: two waves of alignment
What is a cold vortex thunderstorm? It refers to a thunderstorm caused by a cold vortex. Cold vortex is the abbreviation of "cold vortex". In contrast to typhoons, which have a warmer center, the air currents of the cold vortex revolve around a cooler center. Cold vortices can form at different altitudes and latitudes, but on the mainland, the most common are the Northeast Cold Vortex and the Mongolian Cold Vortex. The center of the Northeast Cold Vortex is located in the Northeast region, and the center of the Mongolian Cold Vortex is located in the Mongolian Plateau.
The formation and development of the cold vortex is mainly affected by the westerly wind belt. The westerly wind belt is a prevailing wind blowing from west to east in the mid-latitudes, blowing from the high pressure area of the subtropical high pressure belt to the polar region. Fluctuations often occur in the westerly wind belt, forming troughs (low pressure) and ridges (high pressure). The trough line in the westerly wind belt is called the westerly trough. The westerly trough is a strong dynamic system, and sometimes, under certain conditions, its southern end will gradually cut off, so as to break away from the westerly wind belt and form an independent vortex, which is the formation of a cold vortex.
According to the forecast of the Central Meteorological Observatory, from the 18th to the 20th, there will be light to moderate rain and locally heavy rain in the eastern part of Northwest China, North China, Huanghuai and other places, which is also related to the cold vortex. In short, the activity of the westerly trough and cold vortex will bring a complex and changeable weather process to the mainland, and everyone should pay close attention to the weather forecast and take countermeasures in a timely manner.