From the NOAA Atlas 14 documentation series: “NOAA Atlas14 contains precipitation frequency estimates with associated confidence limits for the United States and is accompanied by additional information such as temporal distributions and seasonality. The Atlas is divided into volumes based on geographic sections of the country. The Atlas is intended as the official documentation of precipitation frequency estimates and associated information for the United States. It includes discussion of the development methodology and intermediate results. The Precipitation Frequency Data Server (PFDS) was developed and published in tandem with this Atlas to allow delivery of the results and supporting information in multiple forms via the Internet. NOAA Atlas 14 Volume 1 contains precipitation frequency estimates for Arizona, Nevada, New Mexico, Utah, and southeastern California (Imperial, Inyo, Eastern Kern, Eastern Los Angeles, Riverside, San Bernardino and Eastern San Diego counties). These areas were addressed together in a single project focused on the semiarid southwestern United States. The Atlas supersedes information contained in Technical Paper No. 49 “Two- to ten-day precipitation for return periods of 2 to 100 years in the contiguous United States” (Miller et al., 1964), NOAA Atlas 2 “Precipitation-Frequency Atlas of the Western United States” (Miller et al., 1973), “Short Duration Rainfall Frequency Relations for California” (Frederick and Miller, 1979) and “Short Duration Rainfall Relations for the Western United States” (Arkell and Richards, 1986). The updates are based on more recent and extended data sets, currently accepted statistical approaches, and improved spatial interpolation and mapping techniques. The work was performed by the Hydrometeorological Design Studies Center within the Office of Hydrologic Development of the National Oceanic and Atmospheric Administration’s National Weather Service”