Precipitation extremes at the Central Sierra Snow Laboratory, California

Information on return periods of precipitation in snow country is essential to a variey of engineering tasks--including estimating structural loading, designing reservoir capacity, and forecasting runoff. Using records from 1899 to 1988, extreme value theory was used to develop 10-, 20-, 50-, and 100-year return periods for precipitation during 1- to 10-day intervals at the Central Sierra Snow Laboratory in California's Sierra Nevada. Precipitation ranged from over 14 cm for the 10-year return period and 1-day interval to almost 70 cm for the 100-year return period and 10-day interval. During the 89-year daily precipitation record, mean daily precipitation was 11 cm but ranged up to 118.2 cm for individual days. Mean precipitation was 38-40 cm for many of the longer (12+ days) events and was over 78 cm for one 10-day event. Precipitation is common at this site with 1-, 2-, and 3-day precipitation periods occurring an average of 25 times annually.