Source Title: Tracking the rain five days ago
The strongest rainfall is here as promised. In fact, as early as July 7, the forecaster team of the Beijing Meteorological Observatory paid attention to the heavy rainfall in this area.
Zhao Wei, the chief forecaster of the Municipal Meteorological Observatory, was on duty at the time. She and her colleagues found that various weather forecast models at home and abroad stably forecasted regional heavy rainfall in North China from the 11th to the 12th. “At that time, I paid a lot of attention, and quickly started to pay close attention and research.”
Zhao Wei said that whenever there is a relatively large weather process, forecasters should not only pay attention to the progress of the forecast, but also start to do analysis and research, “analyze historical heavy rain cases, find out the reasons for the previous inaccurate reports, and analyze them. Summary.” They likened this process to “scientific research”, like the “7.21” rainstorm in 2012, the “7.20” rainstorm in 2016, and the “8.12” rainstorm in 2020. These three are more important. The process of torrential rain is the focus of forecasters’ analysis.
In fact, every time the weather process is forecasted, the forecasters will have a prediction of the general appearance in their minds. “This time the process is a typical torrential rain in North China.” Zhao Wei said, but the specific quantitative issues such as the specific rainfall area and how much rainfall need to be further tracked and determined. On July 9th and 10th, a weather conference was held throughout North China. The results of the consultation further confirmed the heavy rainfall process.
72 hours before the precipitation, Beijing’s Ruitu forecasting system has begun to work, and forecasters have begun to estimate the amount of precipitation and fall areas brought about by this process. On the afternoon of July 10th, Zhang Linna, the chief forecaster of the Municipal Meteorological Observatory, gave a specific forecast of the heavy rainfall process: Beijing area ushered in the strongest rainfall process from the evening of the 11th to the night of the 12th. It is expected that the process rainfall will reach torrential rain to heavy rain. The average rainfall in the city can reach 60-100 mm, 100-150 mm in the western and northern regions, and 200-300 mm in individual spots. This process has the characteristics of long duration, large accumulated rainfall, high wind, and obvious convective characteristics.
The strongest rainfall process this time initially started in Sichuan and went all the way north. When the rainfall system entered Shanxi and Henan, the forecasters could clearly see the structure of the cloud clusters on the satellite cloud images. They hurriedly used the actual situation and the model forecast to do a comparative test to see where the rain was. Whether the magnitude and so on meet expectations.
At about 15:00 on July 11, the rainfall echo was in Hebei. Zhai Liang, the chief forecaster of the Municipal Meteorological Observatory, concluded based on the analysis of the cloud picture: the first wave of rainfall is expected to affect the Beijing area at about 18:20.
As expected! At this time, the “advanced troops” with heavy rainfall first arrived in the Fangshan area of Beijing. There was a gust of wind and showers, and then the rain gradually spread to Shijingshan, Mentougou, and Fengtai, and then rushed to the whole city. At the same time, the chief forecasters Zhang Yingxin and Guo Jinlan on duty forecast the second wave of rainfall from 22:00 to 23:00 on the 11th, and the third wave to occur from 5 am to 6 am on the 12th. In other words, the precipitation was intermittent, and there were about three periods when the precipitation increased significantly.
From the evening of the 11th to the daytime on the 12th, the rain fell intermittently one day and one night, and then rested for a while. As of 15:00 on the 12th, the city’s average rainfall has reached 87.3 mm, and the average urban area is 101.1 mm. The city’s largest rainfall point is in Fangshan Beijiao, with a cumulative rainfall of 186.6 mm. There is no doubt that the strongest rainfall since the flood season is worthy of the name.
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