PERMFILE102397 - Laserfiche WebLink

Home Browse Search

• 2.1.3 Prevailing Winds The prevailing direction of air movement into the Craig, Colorado, area is from the west which is typical of the synoptic air movement patterns of mid- latitudes. These winds arrive comparatively dry from [he Pacific Coast having lost most of their moisture passing over mountain ranges to the west. The relatively open areas to the north and to the northwest of Craig permit some- what easier access to Ch is area for storms from the north, Chan [o other more protected areas in western Colorado (Berry, 1966). 2,1.3,1 Geological Formations - Their Effect on Airflow Patterns Second only to the synoptic air movement of a region is the proximity of pro- minent geological formations which influence local surface wind patterns and speed. The Yampa Rivet drainage basin between Craig and Steamboat Springs, Colorado, (40 miles to the east) can be characterized as a very broad box canyon. This topographic feature is the result of mountain ranges extending from 9,000 to 10,000 feet along the south and north to within 30 miles of Craig; and by the Continental Divide, 45 miles to the east, which rises between 10,000 and 12,000 fee[ in the Park Range. The nearly east-west orientation of the "can- yon" floor provides the major axis, controlling local air movement and chan- neling the air flow into an east-west pattern around Craig. Within this "can- yon", downs lope and ups lope conditions are frequently observed, However, in the vicinity of the Craig Generating Station and the proposed mine plan area the effects of ups lope and downs lope air movement are modified because these facilities are located near [he mouth of the "box canyon" (S[earnsRoger, 1974 and Berry, 1966). The Williams Fork Mountains (7350-7900' elevation) are 2 to 2-1/2 miles south of [he Craig Generating Station. This mountain range forms the nearest high • terrain, or local topographic feature, [h a[ can exert significant influence on 2-18