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• in Hayden. Data fiom both locations are presented in this permit application, in order to provide the best
<br />information pertaining to the mine plan area and to indicate the variability in climatological characteristics
<br />[hat may be expected within short distances.
<br />General descriptions of the climate of western Colorado are difficult due to the rugged topography of the
<br />region. Temperatures [end to decrease and precipitation tends to increase with increased elevation. The
<br />climates of local areas are affected not only by altitude, but also by the orientation of mountain ranges and
<br />the effect they have on prevailing winds and local air movements. The elevational difference between the
<br />highest and lowest point in the Hayden-Steamboat Springs region is over a vertical mile. Along the
<br />Yampa River in the vicinity of Craig and Hayden, elevations are about 6,500 fee[, whereas several peaks
<br />along the Continental Divide immediately northeast of Steamboat Springs rise to nearly 12,000 feet.
<br />These peaks are part of the Park Range which is oriented approximately north-south. The Continental
<br />Divide has some pronounced effects on local weather features of the region: (I) it acts as a barrier to
<br />storm systems approaching from [he west, causing them ro veer either to [he north or south; (2) it tends to
<br />restrict the movement of high pressure systems and thus enhance the possibility of air stagnation; (3) it
<br />prevents intrusions of polar air on the east slope of [he Divide from reaching [he west slope; and (4) i[
<br />increases precipitation towards the mountain due to the upslope effect of the topography on eastward
<br />moving storm systems in winter. Although heavy snowfall occurs frequently in winter, stationary high
<br />pressure systems bring clear skies accompanied by relatively warm days and cool nights.
<br />Precipitation
<br />Precipitation is directly related [o local topography. Winter precipitation falls as snow over large areas a[ a time,
<br />whereas summer precipitation is most likely to fall as scattered, local showers or thundershowers. At all times
<br />• of the year precipitation is normally heaviest over the mountain ranges. As shown in Table 13, Precipitation
<br />Summary, 191-1970, Table 14, Precipitation Sunnnary, 1971-1978, and Table I5, Precipitation and Temperature
<br />Sunnnary, the total precipitation at Steamboat Springs is significantly higher than at Hayden; the higher
<br />precipitation rate is due to the close proximity of Steamboat Springs to the Park Range.
<br />[3ased on 46 years of data through 1960, inclusive, the normal annual precipitation at Hayden is 15.45 inches.
<br />Monthly variations in normal precipitation are slight with no distinct annual precipitation patterns. April, May and
<br />October have the highest normals with 1.50, 1.47, and 1.46 inches, respectively, while November, February, and
<br />August have the lowest normals of 1.09, 1.14 and 1.19 inches, respectively.
<br />30d
<br />Although Steamboat Springs is only 25 miles from Hayden and about300 feet higher in elevation, approximately
<br />52 percent more precipitation is recorded on an annual basis. December and January are the months with the
<br />highest normal precipitation figures, 2.46 and 2.97 inches, respectively, and August is the driest month with
<br />normal rainfall of 1.13 inches. ~f1..7 sl.,,,..vd ~^'4 -')^-^- 'X ~ ~ n~ec; t+ @ 54~...-M» 1 ~ - ~'"s ~~°~`~`^
<br />Snowfall
<br />Steamboat Springs averages 163.6 inches of snowfall per year, based on 56 years of data. An average of more
<br />than 30 inches of snowfall occurs in Steamboat Springs during the months of December, January and February.
<br />In Hayden, an average of 96.7 inches of snow falls annually. The highest averages in Hayden occur in December
<br />and January with 22.6 and 21.3 inches, respectively. The difference in snowfall between Steamboat Springs and
<br />Hayden is exemplary of the orognphic effects on precipitation.
<br />Temperature
<br />Temperature data from Steamboat Springs and Hayden are presented in Table 16, Temperature Su+nmary, Means,
<br />1951-1970: Table 17, Temperature Summary, Extremes, 1951-1970; and Table 18, Temperature Summary,
<br />MR 97-1~4 2.04-45 Rccised 10/02/97
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