Although precipitation is a common measurement at weather and climate stations, observations are scarce in the mountains where precipitation patterns are most variable. Existing statistical models cannot accurately describe potential change in precipitation patterns because they rely on current observations. In addition, the sparsely located observations cause some statistical methods to inaccurately simulate precipitation, especially in mountains. A convergent-orographic precipitation model is being adapted to rapidly model precipitation over large regions of complex terrain. It will be used to generate long-period, high-resolution precipitation data.