Is the plum rain coming this year fierce? Heavy rain occurred in some areas, and Shanghai started the plum rain violently.
Today, Shanghai officially opened the plum rain season, and the first day of the plum rain season ushered in the test of heavy rain. According to the monitoring of the Shanghai Central Meteorological Observatory, as of 15:00 today, heavy rain has fallen throughout the city, and some areas have reached torrential rain. As of press time, the blue warning signal for heavy rain and the yellow warning signal for thunder and lightning are still in place. With the start of the "violent plum rain season", many citizens are worried. Will this year's plum rain season be more aggressive?
Meteorological monitoring data shows that as of press time, the heaviest rainfall today occurred in Nanhui New Town, Pudong, with a cumulative rainfall of 66.4 mm. Some residents believe that this is because Shanghai entered the plum rain season late and had accumulated momentum for a long time, so it was able to "make a splash" right after the plum rain season began.
The reporter asked the Shanghai Meteorological Bureau for confirmation. Meteorological experts said that the arrival of the plum rain season in Shanghai this year was not late, and was the same as the annual average. From a meteorological perspective, judging whether the plum rain season has arrived needs to be based on some scientific evidence, including temperature, rainfall, the location and intensity of the subtropical high pressure, etc. Due to the different meteorological circulation situations in different provinces and cities, the arrival of the plum rain season will also be different. This year, Jiangsu and Shanghai entered the plum rain season on the same day, while Zhejiang entered the plum rain season as early as June 9.
In recent years, the plum rain season in Shanghai has not been typical, with either high temperatures or little rain. What are the characteristics of this year's plum rain season? Experts from the Shanghai Climate Center said that the overall situation of the plum rain season in Shanghai this year is relatively typical, which is basically consistent with the impact of the plum rain season in the middle and lower reaches of the Yangtze River, namely: the subtropical high pressure in the western Pacific is distributed in a belt and carries a large amount of warm and humid air to the middle and lower reaches of the Yangtze River. The mid- and high-latitude circulation in Asia presents a single-block type of Lake Baikal. The cold air moves southward along the low-pressure trough on the south side of the blocking high pressure to the middle and lower reaches of the Yangtze River. The confluence of cold and warm air causes heavy precipitation at the beginning of the plum rain season. The rain belt has a clear process of jumping north from the Jiangnan region to the middle and lower reaches of the Yangtze River. Today, Shanghai is affected by the northward jump of the rain belt, which is why heavy precipitation is occurring.
The term "plum rain" originated in China and can be traced back to more than 1,000 years ago. Since Shanghai began to keep meteorological records in 1873, continuous observations have shown that the start and end of the plum rain season in Shanghai have shown a significant delay in interdecadal fluctuations, while the amount of plum rain has shown a slight increase. These characteristics are related to the impact of climate warming and the interdecadal variability of the ocean on the East Asian summer monsoon.
Among them, the interannual variation of the start and end of the plum rain season in Shanghai has been obvious since 1991, with the start of the plum rain season ranging from May 30 to July 6 and the end of the plum rain season ranging from June 23 to July 26. Since historical records began, the year with the most plum rain was 1999, when there were as many as 8 days of heavy rain during the plum rain season, including 2 days of heavy rain, and 4 consecutive days of continuous heavy rain. In 2020, the middle and lower reaches of the Yangtze River were hit by a violent plum rain season, and Shanghai also had 3 days of heavy rain during the plum rain season.
But in general, the average start date of the plum rain season was June 19, and the end date was July 10. The total amount of plum rain in the whole city was 240.1 mm, and the amount of plum rain in the central urban area was 262.5 mm. Compared with the early plum rain season in history, the modern plum rain season in Shanghai showed some atypical characteristics, mainly in the following three aspects: the degree of continuous rain was weakened; the spatial distribution of precipitation was uneven; the phenomenon of weak precipitation decreased, and the number of strong precipitation increased, and the extreme nature of precipitation was enhanced.
According to the forecast of Shanghai Climate Center, based on the current objective prediction method, it is likely that the end of plum rain in Shanghai this year will be later than usual and the amount of plum rain will be more than usual. The reporter also learned from the Shanghai Flood Control Headquarters Office that the precipitation in Shanghai during the flood season this year will be 20% to 30% higher. The temperature will be slightly higher to above average, and the number of high temperature days will be slightly higher. There will be 1 to 2 typhoons affecting Shanghai, and special attention should be paid to the impact of typhoons heading north from midsummer to early autumn. The flood control situation is not optimistic.
The city's meteorological department reminds that the plum rain belt is expected to remain stable in the middle and lower reaches of the Yangtze River in the next 10 days, and attention should be paid to the impact of heavy rainfall during the plum rain period. The heavy rain in Shanghai will gradually weaken during the day tomorrow, and then the rain belt will swing north and south near Shanghai. In the short term, Shanghai is expected to have two more heavy rains on the 23rd and 25th.
