Under what conditions does embedded convection enhance orographic precipitation?

Although convective orographic clouds generally produce larger local precipitation rates than stable laminar clouds, the impact of this convection on area-averaged precipitation amounts, and hence the large-scale flow, is still not fully understood. To improve this understanding, we conduct a large number of idealised, cloud-resolving numerical simulations of moist flow over Gaussian orography. A wide range of parameter space is considered to capture the dominant environmental and terrain-related controls on convective vigor, condensation amounts, and precipitation efficiency. The results suggest that embedded convection only yields a significant precipitation enhancement in certain well-defined regions of parameter space. This behavior can be qualitatively explained through a consideration of the relevant advective, convective, and microphysical timescales. More quantitative insight is provided through a simple scaling analysis of orographic precipitation that is valid for both stratiform and convective orographic clouds.