Lessons on orographic precipitation from MAP (invited)

Although moisture-laden airflow towards a mountain is a necessary ingredient, the results from MAP taught us that detailed knowledge of the orographically modified flow is crucial for predicting the intensity, location and duration of orographic precipitation. Understanding the orographically modified flow as it occurs in the Alps was difficult since it depends on the static stability of the flow, which is heavily influenced by the complex effects of latent heating, and the mountain shape, which has important and complicated variations on scales ranging from a few to 100's of kilometers. Central themes in all the wet-MAP studies are the ways the complex Alpine orography influenced the moist, stratified airflow to produce the observed precipitation patterns, by determining the location and rate of upward air motion and triggering fine-scale motions and microphysical processes that locally enhance the growth and fallout of precipitation. In this presentation we will review the major findings from the MAP observations, along with related theoretical developments.