University of California Water Resources Center

California receives most of its annual precipitation during the winter season, with large spatial contrasts and temporal variations being observed in the total rainfall amounts. Currently there is widespread understanding of the implications of large atmospheric and oceanic anomalies to the economy and society of the state of California. Typical of this awareness, is the high level of public and government concern at the onset of El Nino conditions in 1997. Therefore, thorough documentation and understanding of the spatial and temporal variability of precipitation in California is a key element in developing efficient and successful programs of water resources management and emergency awareness.