Strong winds and cooling temperatures are actually the "pioneers" of high temperatures! North China says to Jiangnan: I'll drink this bowl of "hot" wine first as a token of my respect

1. The cold front will move southward and westward from the east on the 14th and 15th

Cold air is common in China in spring, and usually moves eastward and southward from Xinjiang. However, the strong cold air that affected most of the north on the 14th and 15th was very unique, moving westward and southward, bringing strong winds, cooling, and sandstorms. However, precisely because it was moving westward, the sandstorms from the sand source areas of Mongolia and western Inner Mongolia did not affect North China, and the strongest cooling area was also in western Inner Mongolia.

1. The cold front will move southward and westward from the east on the 14th and 15th

Cold air is common in China in spring, and usually moves eastward and southward from Xinjiang. However, the strong cold air that affected most of the north on the 14th and 15th was very unique, moving westward and southward, bringing strong winds, cooling, and sandstorms. However, precisely because it was moving westward, the sandstorms from the sand source areas of Mongolia and western Inner Mongolia did not affect North China, and the strongest cooling area was also in western Inner Mongolia.

Although the sandstorm will not come from the east, the strong winds and temperature drop are considerable. There will be northerly strong winds of level 4-5 and gusts of level 6-9 in North China and the Huanghuai region. The average temperature will drop by 4-8℃. The cold air is still quite powerful. In addition, there may be thunderstorms and even local strong convection in southern North China and northern Huanghuai.

Although the cold air is moving strongly southward from the east, the season has finally arrived and the temperature has returned quickly, returning on the 16th, and it is even warmer than before - the first large-scale high temperature process in the north is about to arrive.

2. This year, Lingnan and Yunnan have experienced high temperatures, breaking records in many places, and the country is warmer in spring.

Let’s first talk about the early background of the high temperatures in the north:

Since the beginning of 2024, Hainan, Yunnan, Guangxi and southern Guangdong have experienced some high temperature weather. However, these places are in or close to the tropical monsoon zone. In a sense, there is no winter, and some even have summer all year round, so high temperatures are not surprising.

However, if we examine the extremes, it is still quite prominent. The high temperatures in Yunnan and South China have exceeded 40°C, many of which have broken the historical extreme records for the same period. This kind of "extreme warming" situation is also common in the north.

The red dots are the locations of the stations where the daily maximum temperature exceeded the extreme value for the same period, and the numbers are new records

The background of the extreme values ​​above is that the country has been warmer since March:

Anomaly: the difference between the current mean and the mean of the same period in previous years

In line with the National Climate Center's earlier forecast in April that the country will be warmer in May:

It is almost certain that this spring will be significantly warmer than normal, and with the high certainty of a high temperature process in the north in mid-to-late May, the word "almost" can be removed.

3. From May 17 to 19, North China and the Huanghuai region will experience the first widespread high temperature weather this year

1. The high temperature process in the North China Plain is basically confirmed

Large-scale high temperatures are caused by large-scale weather systems, which are highly predictable, so this process can be determined relatively early. This will also be the first high temperature weather process with a major impact in the area north of the Nanling Mountains in my country this year (some basin areas in Xinjiang, especially deserts and Gobi and their surrounding areas, have experienced high temperatures many times, but the impact has been relatively small).

At present, the high temperature period is mainly from the 17th to the 19th, and the hottest day is the 18th. The areas are mainly in the low-altitude areas of North China and Huanghuai, that is, the North China Plain and Fenwei River Valley. The provinces involved are mainly: Shanxi-Fenhe Valley, Beijing-Tianjin-Hebei-Eastern Plain, Shandong-North and West, Henan-Central and Northern Plains, Anhui-North, Shaanxi-Central and Eastern Guanzhong Plain. The areas with daily maximum temperatures above 35℃ are roughly estimated as follows, and the range above 30℃ will be larger.

2. The main characteristics of this high temperature: daytime + dry heat + low altitude

Although the high temperature is the same in all regions and at all times as measured by thermometers that specifically record the daily maximum temperature, the so-called high temperature varies greatly when factors such as the influencing period, circulation background, and hygrometer are taken into consideration.

First of all, it is easy for the maximum daily temperature to break 35 degrees Celsius during this hot weather, but the temperature difference between day and night is large, and the minimum daily temperature is mostly below 25 degrees Celsius, and it is not hot at night or even cool.

Secondly, the high temperature area is mainly controlled by the south wind, but it is dry, and the relative humidity is below 40% most of the time, so it is not stuffy.

Finally, it is important to emphasize that the high temperatures this time are mainly at low altitudes, that is, in river valleys and plains. In fact, if the temperature is transferred from the narrow ground to the air, the range of the air mass that caused this high temperature weather is far greater than the actual high temperature area, and even the high temperature area is only at its edge. This is determined by the cause of the high temperature.

3. Causes of high temperature: sunny ground + sinking in the sky + warm air from northwest extending eastward

First, it will be sunny. After the influence of the cold front on the 14th and 15th, the whole north is covered with clear skies. Under the continuous strong sunshine less than 40 days away from the summer solstice, the earth is very efficient in heating the atmosphere during the day, and the wind in the whole area is relatively small, so the heat will not be carried away in large quantities.

Secondly, the sinking movement of the middle and upper atmosphere is not only the reason for the large-scale clear sky and few clouds in the north mentioned above, but also the result of its sinking and warming is that the heat given by the earth during the day can be sealed in the low altitude to form a "warm cover", which is conducive to reducing the heat lost by the ground due to long-wave radiation to outer space on clear nights, so as not to make the daytime sunny and dry, and help the accumulation of heat to form high temperature. The center of this low-altitude large warm air mass is in the central and western Inner Mongolia and the northern part of the northwest region: because the high altitude can receive more solar radiation + the ground in the Gobi Desert has the highest efficiency in heating the air.

Finally, this large low-altitude warm air mass over the entire North China and Northwest China slowly stretched out eastwards from the 17th to the 19th, covering the low altitude of the North China Plain. It helped to preserve the heat from the sun on the flat ground, and thus a high temperature process was formed.

It is worth mentioning that the prevailing wind in the entire North China Plain during these three days was southerly. There are two important and easily misunderstood points that need to be explained: First, although it is a southerly wind, it is cooler, so it does not bring warm advection and does not contribute to the high temperature process; second, precisely because it is a southerly wind rather than a westerly wind, the possibility of the föhn wind from the plateau as the main cause of the high temperature is ruled out. The föhn wind is not completely ineffective, but the effect is very small this time, and at most it has a blessing effect in a small area along the mountain. The most fundamental thing is the sun and the protection of the sun effect.

In summary, the first high temperature in the area north of Nanling Mountains came a little early this year. When the temperature in Jiangnan and even most of Guangdong has not yet reached 35℃, Beijing is about to reach it. What will happen this summer?

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