PERMFILE116446 - Laserfiche WebLink

Home Browse Search

• 2.6.3 TEMPERATURE As is typical of the interior mountain area, temperatures have strong seasonal and doily variations between high and low, as is shown in Exhibits 2.6-3 and 2.6-4. Between April and October, the difference between the mean maximum and mean minimum temperature is more than 30 degrees in every month. For Steamboat Springs the highest recorded temperature was 96 degrees on July I I, 1954, and the lowest was -50 degrees on January 12, 1963. For Yampa the highest recorded temperature was 88 degrees on July 26, 1964, and the lowest temperature was -24 degrees on January 21, 1966. The elevation of the Edna Mine ranges from 7,000 to 8,300 feet, while Steamboat Springs is at 6,800 feet and Yampa of 8,000 feet. So it is probable that the mine is several degrees cooler than either of these stations. Aa partial temperature record at the mine showed several days with the low below -50 degrees in January 1979. The normal freeze free period is between June and August and averages approximately 80 days. However, the normal growing season is only 26 days at Steamboat Springs (BLM, 1977). As is shown on Exhibits 2.6-3 and 2.6-4, freezing • temperatures can occur in any month of the year with the average monthly maximum temperature below freezing in December and January at Steamboat Springs. 2.6.4 PREVAILING WINDS More than any other climatological factor, the wind regime at the Edna Mine depends upon local topography. The regional winds are from the west (BLM, 1977), unless there is o major weather system moving through the area. The loco) near surface winds are most often o function of the topography. Wind roses for nearby weather stations are shown in Exhibit 2.6-5. The Oak Creek Valley is one of three narrow valleys that connect the broad open plains of the Yampa River at Steamboat Springs, whose elevation is roughly 7,000 feet with the open plains between the towns of Oak Creek and Yampa, whose elevation is 7,500 to 8,000 feet. These volleys act as passages of air moving between the two plateaus so the prevailing wind direction is along the volley axis. Besides winds generated by the connection between different areas, the orientation and geometry of the Oak Creek Valley itself generates winds. As stated in Boundary Layer Climates (Oke, 1978), "The best developed and most • symetric wind system might be anticipated in a deep straight valley with a north south axis", which is a description of the Oak Creek Valley at the Edna Mine site. The wind 2.6-4