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53.2 inches of precipitation for all seven gauges. The upper curve in the figure shows that 25 percent of the episodes had durations of only 1 hour, and 50 percent had durations of 3 hours or less. The middle curve shows that 50 percent of the precipitating hours were in episodes of 12 hours or less. The bottom curve shows that half of the precipitation fell in episodes of 21 hours or more which, according to the upper curve, were only six percent of the episodes. The frequent occurrence (90 percent) of the episodes less than half a day in duration contributed 33 percent of the total precipitation and were therefore of some importance, but clearly the longer storms produced the most precipitation. As noted above, a similar analysis was previously done in the climatological analysis of the storms affecting the Grand Mesa region of western Colorado. The results were generally similar but it appeared that the Grand Mesa episodes were of longer duration. It is also noteworthy that on the Grand Mesa the shorter duration episodes (of half a day or less) produced only 16 percent of the total precipitation compared to 33 percent for the Arizona episodes. Conversely; the Arizona episodes produced more of the total precipitation within a shorter period of time than did the Grand Mesa episodes. Table 3-6 offers a comparison of these two analyses, where the difference in episode duration is quite evident, e.g., 75 percent of the Arizona episodes lasted 7.5 hours or less, while on the Grand Mesa, 75 percent of the episodes lasted 14 hours or less (nearly twice as long). At the 90 percent level the difference in episode duration remained about the same (8 hours longer on the Grand Mesa) but 5 percent 3-43 I I I I , f I , t , t I I , , I I I I