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~~` III IIIIIIIIIIIII III <br />~~ <br />3.4 Climatolooical Information <br />3.9.1 Climate <br />The permit area has a typical alpine climate. Summers are general- <br />ly moderate, with mild days and cool nights. Winters are long and <br />cold, with snow cover during much of the season. The regional <br />climate is dominated by air masses originating from the Pacific <br />Ocean. These masses are modified after passage over western <br />mountain ranges, and consequently acquire semi-continental charac- <br />teristics by the time they reach Colorado. <br />The surface wind flow in mountainous regions is governed by <br />topography and small-scale circulations. The weather station at <br />the Eagle Airport (approximately 90 miles east) is situated in the <br />Colorado River valley on an east-west axis much the same as the <br />project site. A surface wind rose diagram for Eagle is shown in <br />Figure 3.4-1 (U.S. Dept. of Commerce, 1975). The topographical <br />influence on the wind flow is quite evident. The easterly domi- <br />nance is enhanced by the frequent nighttime drainage of air from <br />the mountainsides downstream through the river valley. <br />The regional "mountain-top" air flow, which is more indicative of <br />large-scale circulation, and which is less affected by terrain <br />features than surface winds, is shown in the wind rose in Figure <br />3.9-2 (U.S. Dept. of Commerce, 1977). These data were obtained <br />from the weather station at Grand Junction, which is the nearest <br />location reporting upper-air observations. The 700-millibar level <br />(approximately 10,000 feet) is normally considered "mountain-top" <br />level for meteorological purposes. The dominance of winds with a <br />westerly to southwesterly component is apparent. <br />A meteorological monitoring program has been conducted on the site. <br />The program consisted of TSP and meteorological sampling at twc <br />sites. The primary site was located in the vicinity of the <br />• <br />r <br />U <br />• <br />NCEC - Coal Ridge #1 3-50 ABC/1145/900301 <br />