Abstract
On 12 February 1973 an airflow case study was documented across the San Juan Mountains in south-west Colorado. The main observation system was an NCAR Queen Air aircraft. Several supplementary observations were available from the weather modification project being conducted in the area. The airflow data were synthesized and compared with previous laboratory simulation results over the same area. The orographic cloud contained a number of imbedded convective clouds which had an important effect on the airflow and vertical diffusion processes. A precipitation efficiency was derived using a technique which avoided most of the critical assumptions of previous attempts.
