In the past few days, with a cold vortex in the westerly wind belt southward, a strong cold vortex thunderstorm appeared in the north from April 22, Hebei, Tianjin, Liaoning, Inner Mongolia and many places at the same time broke the earliest rainstorm in history and the daily rainfall record in April, Hebei Qian'an 24-hour rainfall of 86.8 mm, Tianjin Xiqing Station reached the level of heavy rainfall, at the same time, many places accompanied by cold vortex thunderstorms typical thunderstorms, winds, hail and other intense weather processes.
1. The cold wave level cooling forecast in the north has appeared
On the morning of April 24, it can be seen from the satellite cloud map that as the cold vortex and westerly trough cloud system gradually move eastward, the rain in North China, Huanghuai and other places where the cold vortex thunderstorm has passed, and the temperature has begun to stop falling and rise, and then, in a relatively calm weather atmosphere, the temperature in many places in the north of the mainland will further rise to a higher level.
The Central Meteorological Observatory predicts that in the next three days, the temperature in most parts of the north will rise significantly, especially in the south of North China, Huanghuai and other places The maximum temperature during the day will exceed 28 degrees, and Tianjin, Shijiazhuang, Zhengzhou and other major cities are expected to hit 30 degrees. Spring returns to the earth, everything recovers, and people are looking forward to the arrival of the May Day holiday. However, at this time, some forecasts did show a cold wave level of cooling, and there was even the possibility of rain turning to snow. What's going on?
According to the latest forecast of the Central Meteorological Observatory, in late April, many beans in Hebei and Inner Mongolia have shown a significant cooling trend, such as Chifeng in Inner Mongolia and other places, the forecast shows that after the maximum temperature in Chifeng reaches 26 degrees on April 24, the maximum temperature will return to 9 degrees on April 29, and the minimum temperature will return to around 0 degrees, which means that there is a cold wave cooling forecast of more than 15 degrees Celsius.
Second, May 1st strong cold air is coming?
So, where does this cold air come from? It turns out that it is due to the fluctuations of 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 cold vortex.
The cold vortex is a high-altitude cyclonic vortex from the middle and high latitudes, which has deep cold air inside and a lower central pressure than the surrounding area, showing the characteristics of a cold core. Its formation and development are mainly influenced by the westerly wind belt. The cold vortex moves slowly and lasts for a long time, often bringing weather phenomena such as low temperature, precipitation, and strong winds to the underlying surface. If there happens to be warm and humid air currents, it may also cause strong convective weather, such as thunderstorms, hail, tornadoes, etc.
The supercomputer's forecast points out that in the oscillating westerly wind belt fluctuations, after the previous wave of cold vortex, the next wave of cold vortex activity is ready to start, which is a very slow southward cold vortex weather process.
On April 29, the cold vortex will move into the northeast of the mainland, and on April 30, it will drive the cold air southward in the central and eastern parts of the continent, and the northerly wind at the level of 850 hPa will reach the south of the Yangtze River, which means that the cold air will go very deep southward.
3. Supercomputing: local snowfall
Such a cooling range is undoubtedly a big blow to people who are about to usher in the May Day holiday. Originally planned outings, outings, picnics and other activities may be affected. However, if you think that's the full power of cold air, you're very wrong. In fact, as the cold vortex slowly moves south, there is also another precipitation process in the north. It is worth noting that as the temperature drops, there is still a possibility of rain turning to snow in the morning of the 28th-29th in central Inner Mongolia, Xilin Gol League and northern Hebei. At present, the numerical prediction of supercomputers has been reflected. Snow at the end of April is rare, but it is not unusual, showing that the power of cold air from the south at the end of April is still not to be underestimated.