The paper presents the results of a study of the applicability of a system of kinetic equations describing microphysical processes in a three-phase vapor–water–ice system for calculating the kinetics of precipitation formation in a mixed-phased cloud. Experimental data are used obtained from observing the development of a powerful cumulus cloud in the state of Montana, USA, on 19.07.1981. The cloud dynamics is described in terms of a 1.5-dimensional model. The results obtained by the kinetic model are compared with the data obtained by the model with parametrized microphysics.