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<br />A database of observed monthly and annual maximum precipitation totals was assembled <br />and is available at the Colorado Climate Center at Colorado State University. Examples <br />of historic monthly maximum precipitation values for one site, Ouray, Colorado are shown <br />in Table 1 and 2. Figure 1 shows a graph of ranked annual maximum precipitation <br />amounts for specified storm durations at that same site. Similar information can be <br />assembled for all National Weather Service data collection sites in Colorado where many <br />years of data collection have occurred. Most stations have between 15 and 70 years of <br />data, but several dozen sites have monthly and annual extreme values for at least 80 years. <br />Maximum record lengths exceed 120 years at four sites, all east of the mountains. <br /> <br />Data from several other sources in addition to the National Weather Service were <br />examined in order to obtain greater detail at higher elevations. Data from the U.S. Bureau <br />of Reclamation San Juan Project, the National Atmospheric Deposition Program, the <br />National Park Service, the Denver Urban Drainage and Flood Control District, local water <br />departments and districts, the University of Colorado Long-Term Ecological Research <br />Site on Niwot Ridge, the U.S. Forest Service and the Natural Resources Conservation <br />Service were all investigated. For the most part, data from these sources were not <br />incorporated into the Colorado Climate Center's precipitation database. However, <br />monthly and annual maximum one, two and three-day precipitation amounts were <br />digitized and saved for approximately 50 Natural Resources Conservation Service <br />SNOTEL (SNOw TELemetry) stations in the mountains of Colorado. Considerable data <br />quality evaluations were required for these data, especially for data collected prior to <br />1984. <br /> <br />Extreme rainfall dates and amounts were identified using analyzed data from all of the data <br />sources described above. In addition to serving as an excellent starting point for this <br />extreme precipitation study, this data set will also be of great value if and when the <br />original 1973 NOAA Precipitation-Frequency Atlas is updated. <br /> <br />2) Colorado Extreme Precipitation Storm List <br /> <br />The most essential and most time consuming portion of this. study was the assembly of a <br />comprehensive list of extreme storms that have been observed in Colorado or which <br />occurred elsewhere in the Rocky Mountain region but which may be applicable to <br />Colorado. The purpose of this investigative research was primarily to produce a <br />sufficiently complete list oflarge storms so that it was nearly certain thatthe largest <br />storms to have ever been observed in or near Colorado were captured. Secondly, by <br />compiling a large list of storms, it is possible to learn the climatological aspects of extreme <br />precipitation in and near the high elevations of Colorado and the central Rocky Mountain <br />regIon. <br /> <br />2 <br />