The Santa Barbara precipitation enhancement project in coastal southern California is a landmark project in weather modification in the U.S. Having begun in 1950 with operational seeding, the project has enjoyed some significant research phases combined with a long history of operational seeding. The project’s more significant research phases include a) cooperative randomized seeding trials under multi-agency sponsorship from 1957 to 1960, known as Santa Barbara I, b) National Science Foundation sponsored research on cloud-water budgets of Pacific storms from 1960 to 1963, and c) multi-faceted research, including additional randomized seeding trials (ground-based and airborne) during the period of 1967 through 1974, known as Santa Barbara II.

Organized convective bands were identified through the early research as primary candidates for precipitation augmentation, producing a significant proportion of seasonal rainfall and exhibiting favorable characteristics for enhancement via glaciogenic seeding. The precipitation enhancement potential of the convective bands has been estimated to be as high as 50% (from Santa Barbara II), leading to estimates of seasonal increases of up to 25%, since the convective bands produce about 50% of the region’s seasonal precipitation. Further detailed analyses of long term precipitation records concluded that, under average conditions, seasonal precipitation could be optimally enhanced by 18% to 22%, resulting in as much as five inches of precipitation to average seasonal totals. Innovative seeding release methods were developed toward focused treatment of these cloud systems.

Operational seeding has been conducted for decades, interspersed with investigative initiatives. Research results and operational seeding techniques from this project have been applied elsewhere in the region and are potentially transferable to other locations around the world. The project sponsors continue their supportive posture toward research and project enhancements. The progress and evolution of the project in the research and operations realms are summarized. Plans for additional investigative efforts are described.