Strong winds in the north, severe cooling, rain and snow weather, regional heavy rain and strong convective weather in the south … The forecast of the Central Meteorological Observatory shows that from April 1, China has ushered in the largest range of heavy rain and snow weather this year, and a large-scale precipitation process has occurred in the central and eastern regions. On April 2, the Central Meteorological Observatory successively issued a blue rainstorm warning and a blue severe convective weather warning. Why is the weather complicated and changeable in spring? Meteorologists interpreted it.
Fang Yi, chief forecaster of the Central Meteorological Observatory, said that the heavy rain and snow weather process mainly has two characteristics: wide range of precipitation, high intensity and superposition of various disastrous weather. "From April 1 to 5, the land area with accumulated precipitation above 100 mm will reach 230,000 square kilometers, which is the largest heavy rain and snow weather process this year."
Sun Jun, chief forecaster of the Central Meteorological Observatory, said that April 2-4 is the main period of precipitation and strong winds. In terms of precipitation, from April 2 to 5, there were moderate to heavy snow or sleet in eastern Gansu, Ningxia, northern Hebei and central and eastern Inner Mongolia, and there were blizzards or heavy blizzards in central Inner Mongolia. The main snowfall period was April 2 to 3; There are moderate to heavy rains in the southeastern part of Northwest China, the eastern part of Southwest China, Jianghan, Jianghuai, Jiangnan, South China, Huanghuai and the southern part of Northeast China. There are heavy rains in parts of Henan, Hubei, Hunan, Anhui, Jiangxi, Zhejiang, Guangxi, Guangdong and Fujian, and there are local heavy rains. The main rainfall period is from April 2 to 4.
In terms of gale cooling, on April 2, cold air mainly affects northwest China and Inner Mongolia, on April 3, it affects the western part of Northeast China, northern North China, Huanghuai and Jianghan, and on April 4-5, it affects the central and eastern parts of Northeast China, North China, Jianghuai and the south. There will be 4 to 6 winds in the central and eastern regions, with gusts of 7 to 9; From April 2 to 5, the temperature in most parts of the north dropped by 6 to 10 degrees Celsius, and the temperature in the south dropped by 4 to 8 degrees Celsius.
"The land area with a temperature drop of more than 10 degrees Celsius is 940,000 square kilometers." Sun Jun said.
Sun Jun analyzed the causes of this weather process, which was mainly influenced by two weather systems, one was the cold air in the north, and the other was the Jianghuai cyclone from the south. The northern region is mainly affected by cold air. On the morning of April 2, cold air has reached the Hetao area to the eastern part of Gansu, and there are strong winds and cooling weather in Xinjiang, most of Gansu, western Inner Mongolia and Ningxia. Next, the cold air will continue to move eastward and southward, bringing strong winds and cool weather to most parts of the central and eastern regions. However, many places in the south are mainly affected by the Jianghuai cyclone, resulting in a regional rainstorm process.
Sun Jun said that as of April 2, the cold air and the Jianghuai cyclone had not met. Around April 4, the cold air moving eastward and southward will meet the growing Jianghuai cyclone. At that time, the confrontation between cold and warm air will lead to mixed strong convective weather including short-term heavy precipitation, strong wind and local hail, which will affect Henan, Hubei, Anhui and Hunan.
Recently, the weather in some areas has been cold and hot, and this time there has been a sharp drop in temperature. Is it a "cold spring"?
Fang Yi said that in meteorology, "cold in late spring" refers to a weather process in which the temperature drops rapidly in spring due to the influence of strong cold air, and a large range of crops are frozen due to warm before and cold after. "Late spring cold" usually appears from mid-March to April, which generally means that the average daily temperature in Jiangnan area is lower than 12 degrees Celsius for three consecutive days, or lower than 14 degrees Celsius for five consecutive days. As far as this process is concerned, because the temperature drop in the south of the Yangtze River is not severe, the temperature after cooling is close to the same period of the year, and it is unlikely that crops will be damaged by freezing in a large area, so it is unlikely to reach the standard of "late spring cold".
"Spring is the season when cold and warm air meet. The cold and warm air changes. When the cold air is strengthened, the temperature will decrease, but it is still in the process of gradually warming up. Therefore, it is normal for the weather to be cold and hot. The public needs to pay attention to the early warning information issued by the local meteorological department and adjust the dress in time according to the temperature change. " Fang said.
Our reporter Li Hongmei.
Source: People’s Daily
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