San Francisco Airport Stratus Forecast Algorithm

(last updated 8/3/2005)

In 1995, the Federal Aviation Administration launched a "Marine Stratus Initiative," the objective of which was to improve cloud forecast guidance in order to more reliably anticipate changes in the operating capacity at San Francisco International Airport (SFO). MIT Lincoln Laboratory acts as technical lead for the project, in collaboration with San Jose State University, the University of Quebec at Montreal, and the Central Weather Service Unit at Oakland Center.

The local airspace surrounding SFO is prone to frequent low ceiling conditions from May through October due to the intrusion of marine stratus along the Pacific coast. Low cloud or fog conditions can reduce the arrival capacity by 50%, resulting in a substantial number of delayed flights.

The project relies on weather observations from a network of sensors surrounding the Bay area. Data are collected from these sensors at 15-minute intervals and transferred to a database computer located at San Jose State University. The data are processed for display and for input into a suite of algorithms designed to forecast the time of approach zone clearing. The algorithms incorporate several data sources including

• Satellite
• Surface observations
• Model data
• SODAR (SOnic Detection And Ranging)
• Solar radiation
• Numerical model data (COBEL, Statistical Forecast Models)

For a detailed description of the products and real-time output products see the San Francisco International Airport Marine Stratus Initiative Website.