Drop-size distribution measurements in a squall line storm were made using a vertically pointing Doppler radar operating at 35 GHz. The measured drop-size distributions are parameterized to an exponential distribution, and the parameters N0 and &Lgr; are calculated. These two parameters are then related to the measured liquid water content W, and the results show that for W values exceeding 1.2 g m-3, &Lgr; becomes a constant and independent of W, while N0 increases with increasing W. These results are in excellent agreement with collisional break-up theories, and they allow a more accurate modeling of the physical processes involved in the formation and evolution of clouds and precipitation.