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<br />. <br /> <br />I <br />I. <br /> <br />temperatures .and the mean monthly minimum temperatures are provided in <br />Tables 9 and 10, respectively. <br /> <br />These tables also arrange the temperature data in the month of May from highest to <br /> <br /> <br />lowest. Based on the inspection of daily temperature readings forthe month ofMay <br /> <br /> <br />in 1989, peak daily minimum and maximum temperature values are approximately <br /> <br /> <br />15 OF greater than their respective average monthly values (NOAA, 1990), <br /> <br />Using this data, the maximum high temperature and the maximum low temperature that <br /> <br /> <br />would be associated with a 2-year, 5-year, 1 a-year, 50-year, and 1 aD-year snowmelt <br /> <br /> <br />event was estimated, For instance, it was assumed that the IO-year average maximum <br /> <br /> <br />monthly temperature would occur 10 percent of the time, According to the collected data, <br /> <br /> <br />this would correspond to a temperature of 670 F, The 1 a-year maximum daily <br /> <br /> <br />temperature would then be 150 F higher than that or 83 ' F. <br /> <br />The maximum minimum daily temperature was estimated in the same manner. The <br />hourly temperature fluctuation between the maximum and minimum daily temperature <br />was then estimated, The estimates ofthe hourly fluctuation of the daily temperature used <br />in the model for the 2-year, 5-year, 1 a-year, 50-year, and 1 OO-year snowmelt events are <br />shown in Table 11. <br /> <br />Table 11 also supplies the temperature fluctuation of the average monthly temperature. <br />Since this is used to estimate the average monthly snowmelt in the month of May, IS' <br />F is not addedto the average monthly values, <br /> <br />The adiabatic rate of cooling or lapse rate for the cooling of temperature with a given <br />rise in elevation must also be estimated and input into the model. Assuming saturated air, <br />an elevation range of8,000 feet to 11,000 feet, and an expected temperature range from <br />36'F to 68' F, Figure 3.2 in V,T, Chow's Handbook of Applied Hydrology (1964) <br />shows a lapse rate of about 2.5'F for every 1000-foot rise in elevation, <br /> <br />It was also assumed that there would be approximately 56 inches of snow on the ground <br />in May and that the water content of the snow would be I inch of water for every II <br />inches of snow, For every 1 OOO-foot increase in elevation, the amount of remaining snow <br /> <br />19 <br /> <br />~: (! <br />