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iii iiiiiiiiiiiu iii <br />sss <br />WesC Elk Mine <br />a 2.04.8 Climatologicallnformation <br />Doc Date:12111/2001 <br />The West Elk Mine site lies within the North Fork Valley near Somerset, Colorado. At the mine <br />site the valley is quite narrow and steep-sided and follows a general east-west orientation. Figure 1 <br />in Section 2.01 is a map of west central Colorado showing the site and the general vicinity. <br />Considerable topographic variation across the mine site, and west central Colorado in general, <br />results in mazked fluctuation in seasonal and average precipitation and temperature values for the <br />entire area. <br />The mountains of the Continental Divide provide an effective barrier to the movement ofmoisture- <br />laden air that reaches the Eastern Slope of the Rocky Mountains from the Gulf of Mexico. Thus, <br />under this influence, two basic types of climate, semi-arid and undifferentiated highlands are <br />chazacteristicofthe general azea where the mine is situated. Temperatures can range below freezing <br />in the winter and yet in the summer, with the exception of higher elevations, can be extremely <br />warm. The precipitation that does fall originates from the Pacific Ocean weather systems and most <br />frequently occurs in the winter. <br />Regional <br />The West Elk Mine study area is subject to a synoptic pattern from a westerly direction. This is <br />greatly modified by daily up-canyon and down-canyon wind flows typical of mountainous terrain. <br />• Stable air conditions are known to occur in the North Fork, primarily during the winter. From fall to <br />spring, considerable snowfall occasionally accompanies the low pressure storms. Occurrences of <br />severe weather are infrequent. <br />Figure 12 shows the West Elk Mine site and the stations used for temperature data collection <br />(Paonia and Paonia 3 SE climatic stations) and precipitation data collection (Paonia, Paonia 3 SE <br />and Wilcox Ranch climatic stations). <br />Temperature <br />The closest station to Somerset where temperature data have been gathered is Paonia. The monthly <br />temperature summary has been recorded for highest maximum temperature observed, lowest <br />maximum temperature observed, and mean monthly temperature. This includes data for 15 yeazs <br />before and including 1972. The Paonia 3 SE climatic station was also a source of temperature <br />information. The same treatments of data occur here. Graphs of the highest and lowest maximum <br />temperatures observed and mean monthly temperatures for each station's period of record are <br />included as Exhibit 22. <br />According to the data from 1957 and before, the temperature at Paonia 3 SE station has ranged <br />from -28 °F in January 1913 to 100°F in June, 1927, July and August, 1934. Typically January has <br />the lowest minimum temperature. July is consistently the hottest month (Colorado Climatologist, <br />Departmentof Atmospheric Sciences, CSU). <br />1~.J <br />2.04-1 10 1/94 PROS; 8/94 rR7l; 6.95 PRP6 <br />