Forecasting medical resource requirements during combat operations is dependent upon reliable estimates of the anticipated patient load. Traditionally, mean patient load estimations are used to determine the medical resources and supplies. However, these approximations can underestimate the resources needed to treat casualties during certain peak periods of an operation. This paper discusses the use of percentile estimates in forecasting patient loads as an alternative to using measures of central tendency. To assist in providing alternative estimates of ground casualty rates, the SLICECAS model has been developed to compute the varying percentile estimates. Design and construction of the model is based on data and trends observed during previous combat operations.