We have developed a numerical model for examining the thunderstorm electrification process in which we assume the electrification is entirely due to noninductive charge transfer between colliding ice crystals and hail. Since this ice-hail charge mechanism is very dependent on particle sizes and distributions, we use an explicit microphysical framework. To maintain simplicity, the electrification model is kinematic, thus the temperature and velocity fields are input into the electrification model. These fields can be either calculated by a background model or retrieved from observations. For this study, we have used the cloud model of Taylor (1989) to generate the temperature and velocity fields to examine the July 19, 1981, CCOPE thundercloud. Using these fields, the electrification model produced time-dependent ice particle concentrations, radar reflectivities, charge and vertical electric field distributions in good general agreement with those observed. The model produced a maximum electric field strength of 1.27 kV cm-1, which is on the order of that needed for lightning initiation, and this maximum occurred very close to the time of the observed discharge (as inferred by the sailplane measurements). Thus the ice-hail charge mechanism appears to have played an important role in the electrical development of the July 19 cloud. The details of the electrification depended on the liquid water content and the glaciation processes, and particularly on the ice crystal characteristics. Rapid growth of the crystals to riming sizes (>400 μ) yielded the most efficient charging. The electrification was also sensitive to the ice-ice sticking efficiency but not to the characteristics of the large riming ice. ¿1991 American Geophysical Union