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<br />.2 <br /> <br /> <br />>- <br /><( <br />o <br />a:: <br />w <br />0- <br />Cf) <br />w <br />:r <br />u <br />z . 4 <br /> <br />. 3 <br />. 2 <br /> <br />. 1 <br /> <br />o <br />1899 <br /> <br />1909 <br /> <br />1 9 1 9 <br /> <br />1949 1959 <br />RECORD <br /> <br />1929 1939 <br />YEARS OF <br /> <br />1969 <br /> <br />3.0 <br /> <br />2.5 <br /> >- <br /> <( <br />2.0 0 <br /> a:: <br /> w <br /> 0- <br />1 . 5 Cf) <br />a:: <br /> w <br /> I- <br /> w <br />1 . 0 :2 <br /> I- <br /> Z <br /> w <br />0.5 u <br /> <br />o <br />1 979 <br /> <br />Figure 5.- Variation in intensity of precipitation events. Annual precIpItation was <br />divided by the number of days precipitation was received. Dashed line represents the <br />mean value; dotted lines are one standard deviation above and below mean. <br /> <br />each have produced precipitation amounts within 5 cm (2 in) of each other. Precipitation has <br />increased nearly fivefold in a I-year period, from 23.4 cm (9.2 in) in 1949 to 116.3 cm (45.8 in) in <br />1950. The magnitude of wet falls gradually increased until 1964, when a maximum of 128.0 cm <br />(50.4 in) was recorded. Maximums have decreased since then. <br />Figure 7 illustrates the frequency distribution of fall precipitation by 12.7 cm (5 in) precipitation <br />class, The histogram is skewed to the right and the median of 37.1 cm (14.6 in) is significantly less <br />than the mean, 44.5 cm (17.5 in). Three unusually wet falls (1950,1955, and 1964) widen the range <br />of values. The drier falls are fairly consistent-remaining near 20 cm (8 in). In approximately <br />1950, the low values begin the same gradual increase shown by the higher values. Table 5 lists the <br />individual years in each histogram class. <br />Unless adequate reservoir capacity is available to hold the increased precipitation resulting from <br />weather modification, some of the increase would pass through the system. An increase in fall <br />precipitation would have little chance of affecting the area's ecology. It would increase streamflow <br />to reservoirs, <br /> <br />Winter.- Winter precipitation (January through March) exhibits an irregular sequence much <br />the same as annual precipitation (fig. 8). This similarity reflects the dependence of annual precipi- <br />tation upon the winter contribution. The first 15 years of the 20th century (1900-1915) are <br />characterized by extremely high precipitation amounts in alternate years. During the following 20 <br />years (1916-36), winter precipitation drops sharply with nearly all years at or below the mean. The <br />five driest winters on record occurred in this period. The following 10 years (1037-46) are very <br /> <br />1-10 <br />