We used the Clark-Hall numerical model to study the initation of precipitating convection in flow over heated mountains. Our studies with idealized flow over an elliptical mountain indicate that precipitating convection is more likely to form when the wind flow is parallel to the long axis of the ridge than when it is perpendicular to the long axis of the ridge. Likewise precipitating convection is more likely to initiate if wind speeds are slower than if they are faster. Under these more favorable circumstances, the air parcels gain more heat from the elevated heat source.

With the same numerical model, we studied flow over the central Rocky Mountain topography. The model was initialized with a single sounding with vertical speed shear but no directional shear. The temperature and humidity were typical of summertime conditions in the region. The number and location of convective initiation places varied with the wind direction. Total precipitation over the domain also was a function of wind direction. Slower wind speeds had more precipitation locations and less storm propagation downwind resulting in greater precipitation in the mountains but less on the surrounding plains. A sounding with increased CAPE produced more convective initiation locations with greater propagation downwind resulting in the greatest amount of precipitation over the entire domain.