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Based on the quality control of observational data, the heavy hailstorm that occurred in Yangjie Town, Weining County, Guizhou Province on June 28, 2018 is analyzed. The study combines a fuzzy logic hydrometeor identification algorithm with the mesoscale numerical model WRF and uses the X-band dualpolarization radar located in Xueshan Town, Weining County, Guizhou Province. The results show that there is a good consistency between the observation and model simulation results of this hail process, which mainly goes through four stages: development, ripeness (hail formation), ripeness (hail shooting) and attenuation (disappearance). (1) Development: Caused by the riming between ice crystals and surrounding super-cooled cloud water, low-density graupel (LDG) is formed near the cloud layer of -20 ℃ (5.0~6.8 km). Caused by the riming between aggregation (AG) and surrounding super-cooled cloud water, high-density graupel (HDG) is formed near the cloud layer with a terrain clearance of 2.6~4.2 km. (2) Ripeness (formation): AG is the main source of graupel embryo for LDG and HDG. The rain mixed with hail (RH) is initially formed near the cloud layer of - 20 ℃ (4.2~6.8 km) and it is caused by a small amount of HDG which collides with and freezes the super-cooled cloud water. (3) Ripeness (hail shooting): LDG is largely formed by coagulation. HDG develops from two sources: one is the riming with the AG particles (3.4 ~ 6.0 km) as the HDG embryo source, and the other is the gravity sedimentation by the top LDG particles (6.8 ~ 9.3 km), in which the particles develop into a large amount of HDG through coagulation with other ice phase particles during sedimentation. Finally, the HDG develops into the RH. (4) Attenuation (disappearance): HDG grows slowly by colliding with the super-cooled cloud water near the cloud layer of 0 ℃ (3.4 km). While falling continuously, LDG and HDG are gradually converted into liquid precipitation due to obvious melting effect. [ABSTRACT FROM AUTHOR]

In order to explore the evolution characteristics of isolated single hail embryos in Weining area, the evolution characteristics of graupel particles during a hail storm on March 30, 2018 were studied by using fuzzy logic phase state recognition algorithm based on dual-line polarization radar data. The results show that there is a supercooled water accumulation area during the hailstorm development stage on March 30, 2018, and the accumulation area was further expanded in the mature stage and maintained to the dissipating stage. Low-density graupel is distributed in 3～7 km, high-density graupel in 0～3 km, supercooled water in 1～4 km, and hail in 0～6 km. Both high-density graupel and low-density graupel contribute to the generation of hail. However, from the analysis of the whole hail falling stage, high-density graupel is the main source of hail in this hail storm. Hail area and supercooled water accumulation area correspond to high reflectivity area. Updraft brings high-density graupel to supercooled water accumulation area to form hail, which is the main mechanism of hail formation in this process. Through the analysis of hail storm mechanism, relevant conceptual model was established. [ABSTRACT FROM AUTHOR]