Due to the extratropical cyclone, most parts of North China has witnessed torrential rain to very torrential rain with local extremely torrential rain form July 11 to July 12 2021 (Figure 1).
This rainfall event has the characteristics of wide impact, large accumulated rainfall amount, obvious windy weather as well as record-breaking strong local rainfall. The accumulated rainfall in most areas of North China is 50-200 mm, and the local rainfall in Miyun, Hebei, Handan and Qinhuangdao is 220-343 mm. The daily rainfall of 7 national meteorological observatories in Hebei and Henan broke previous records for July. Among them, Jize (206.4 mm) in Hebei and Huaxian (211.7 mm) in Henan has exceeded the historical record.
Regarding this extreme event, the grid forecasting products by National Meteorological Center (NMC) of CMA accurately grasped the scope, intensity and evolution characteristics of the heavy precipitation (Figure 2). Threat Score (TS) of the torrential rain forecast on July 11 and July 12 reached 0.53 and 0.45 respectively, both exceeding the forecast results of various raw global models. In addition, NMC's daily extreme precipitation forecast products also performed well for this extreme precipitation event (Figure 3). (Zhao wei, Wang Yi)
Figure 1. Observed rainfall in North China between 11 July to 12 July 2021 (Unit: mm)
Figure 2. Comparison of 24-hour rainfall grid forecast (shaded) in North China from 00 UTC July 11 to 00 UTC July 12 (left) and from 00 UTC July 12 to 00 UTC July 13 (right) with observations (dotted) (Unit: mm)
Figure 3. Return period forecast (Unit: years) of rainfall in North China based on 24-hour QPF: from 00 UTC July 11 to 00 UTC July 12 (left) and from 00 UTC July 12 to 00 UTC July 13 (right)