Ground Snow Loads for the Western United States: State of the Art

Abstract

A standard defines ground snow loads for much of the nation, with the exception of an 11-state area of the West where the terrain and complex weather patterns require local, regional, and statewide studies. Hence, many western states have published their own standards, which use data from the Natural Resources Conservation Service and the National Weather Service. The data are analyzed using a variety of snow densities, various probability density functions, and several mapping strategies. This paper presents a summary and information, along with unique features, for 11 western U.S. state reports. Many individual state studies do not agree at state borders, and frequently the standard specifies that case studies are required. Future study is suggested to (1) determine the effects of combining values from different probability density functions, (2) reconcile differing values at state borders, and (3) determine the return period that yields a reliability index of 3, with a load factor of unity so the risk level for snow loads equals that for wind and earthquake loads.