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Colorado July 2-3, 1981, but fell over a largely unpopulated area. Based on observed floodwaters, maximum rainfall of up to 16 inches in less than six hours was estimated. In contrast, much of the Fort Collins storm occurred over heavily populated areas. By all indications, this is the largest rainfall ever documented over a developed urban area in Colorado. Remarkably, just 24 hours after the Fort Collins storm, another huge rainstorm developed. The Pawnee Creek storm developed over eastern Weld County and western Logan County during the evening of July 29, 1997. By the time the rains ended early on July 30th, more than 15 inches of rain had fallen near the storm center. Rainfall rates were comparable to the Fort Collins storm but the storm was several times larger in area. As a result, the Pawnee Creek storm will rank near the top of the list of Colorado's most extreme rainstorms. It is interesting to note that three of the largest historic storms identified in the McKee and Doesken study occurred in Larimer County: . LivermorelBoxelder (North Fork Poudre River and Boxelder Creek) May 20-21, 1904. Few rain measurements were available, but 8.00 inches was measured and heavier rainfall totals were likely. . Redstone Canyon, September 2-3, 1938. 6-10" estimates 01ery heavy rains were observed along the Front Range from west of Denver northward to Fort Collins and adjacent foothills.) . Big Thompson Canyon, July 31, 1976. 12" in less than 6 hours with 139 confirmed fatalities. All three of these storms produced severe flooding, but the Big Thompson flood claimed by far the most lives. In terms of meteorological conditions, the Big Thompson storm seemed similar to the Fort Collins storm. However, since it occurred over mountainous terrain, the floodwaters were funneled into a single steep-gradient channel therefore concentrating damage and fatalities. Local Perspective How often in the past has Fort Collins experienced extremely large or intense rainstorms? Was this a lOO-year storm, a 500-year storm or worse? These questions have been asked countless times by those experiencing the flood and those planning for the potential for future floods, Fort Collins is fortunate to have an excellent source of data for historical analysis and comparison, Daily weather observations have been taken without interruption since 1889 on the campus of Colorado State University. Several analyses have been conducted in order to define what place in history this recent rainstorm deserves. As we interpret these results, it is important to note that a single measurement point in the middle of town may not accurately reflect the amount ofrain that may have fallen in other parts of the city. Just as we experienced in the July 28, 1997 storm, in nearly every storm 34