Hebei, Shanxi provinces in North China suffered from severe drought in the spring of 2017. The drought had a certain impact on crop sowing and growth. Cloud seeding is helpful to alleviate drought. To carry out cloud seeding scientifically and accurately, based on the Cloud and Precipitation Explicit Forecast System (CPEFS_v1.0) and observational data, a typical low-trough cold-front cloud system precipitation process that occurred in North China from May 22 to 23, 2017, is studied. Choosing the Xingtai station in Hebei Province for an example, the cloud system structure at different precipitation stages and cloud seeding conditions are explored. The results show that when Xingtai is located behind the ground cold front and in front of the 700 hPa trough, strong rainfall occurs due to uplift of the front. The maximum rainfall in 10 minutes exceeds 2.0 mm, and the water vapor flux below 850 hPa at this stage is greater than 21 g·hPa^-1·cm^-1·s^-1. As the cloud anvil moves over Xingtai, the high-level cold cloud composed of ice and snow crystals transforms into a cold-warm mixed cloud. The mixing ratio of low-level cloud water, middle-level supercooled water and graupel is significantly higher. The main process of rainfall formation includes the collision of raindrops and cloud droplets, the melting of graupel. When Xingtai is located behind the 700 hPa trough and in front of the 500 hPa trough, the precipitation transforms into light rain formed by deep stratus clouds. The content of water vapor and cloud water in the middle and low layers decreases apparently at this stage. The rising movement mainly appears in the cold area and weakens obviously. The cloud system is still a mixed cold-warm cloud, but the mixing ratio of supercooled water and graupel decreases. The precipitation is mainly produced by the melting of graupel. The precipitation gradually dissipates after the 500 hPa trough transits. The cloud seeding time mainly occurs in the frontal uplifting-heavy rain period and the deep stratus cloud-light rain period. The seeding height is located at 4.0-7.9 km. And the strong seeding area is at the height of 4.0-5.5 km, the area with abundant supercooled water.

Based on daily precipitation data of 17 national ground meteorological observation stations in Shijiazhuang since their establishment to 2019, the temporal and spatial characteristics of snowstorm days were analyzed, and the temporal variation characteristics of snowstorm days at 5 representative stations with different geographical environments were further analyzed by using Morlet wavelet analysis and sliding t-test methods. The results are as follows: (1) The snowstorm days decreased gradually from west to east in Shijiazhuang, and there were more snowstorm days in mountain area than in plain, and the urban area of Shijiazhuang was in a high value zone of snowstorm days. (2) The starting date of snowstorm in Shijiazhuang was October 31 at the earliest, and the ending date was April 19 at the latest. (3) From 1972 to 2019, there were 42 days of snowstorm at 17 stations, and greater than or equal to 3, 7 and 10 stations occurring snowstorm accounted for 57.1%, 35.7% and 26.2%, respectively. The snowstorm occurring in the whole region was only 4 days and accounted for 9.5%. (4) The percentage of snowstorm days since 2000 was the largest, and during 2005-2013, snowstorm occurred frequently. (5) The quasi-period and the first major period of snowstorm days in the whole time domain were both more than 10 years at each station, and it was in the period of less snowstorm after 2014 at five representative stations. (6) The time series of snowstorm days at 4 representative stations were abrupt. (7) The spatial distribution of maximum and average precipitation on snowstorm days in Shijiazhuang showed larger in mountain area than in the plain, and the large value center was in the urban area of Shijiazhuang.