Laserfiche WebLink
<br />.. <br /> <br />e <br /> <br />e <br /> <br />4. Snowmobile access <br /> <br />Snowmobile access to and around barrier tops was based on map analysis, and, in some <br />cases, on opinions of persons familiar with particular areas. In general, more rugged the <br />terrain results in more difficult oversnow travel. Besides the difficulty of uphill <br />snowmobile travel under some snow conditions, avalanche danger increases in more <br />rugged terrain. For ex~ple, most snowcourses in the Wyoming Range are serviced by <br />helicopter, in spite of generally.good snowmobile travel, because of known avalanche <br />danger. The existence of unplowed. roads and trails markedly improves snowmobile <br />access. <br /> <br />5. Conifer forest cover <br /> <br />Conifer forest cover implies the existence of small clearings, protected from the wind, <br />which are suitable for operation of precipitation gauges. Aspen and other deciduous forest <br />offers limited protection from the wind. Estimation of forest cover was based on opinions <br />of persons familiar with the areas and study of large-scale maps which indicate type of <br />forest cover, if any. . <br /> <br />6. Along-the-wind extent <br /> <br />The along-the-wind dimension was based on estimation of probable low-level flow during <br />storms. Terrain tends to steer the flow in the lowest several hundred meters above it to a <br />direction perpendicular to the barrier's major axis. For example, investigations over the <br />Grand Mesa of western Colorado revealed low-level flows from south or north during <br />storms with upper level flows from southwest to northwest, respectively. <br /> <br />An along-the-wind dimension for the higher elevations (sometimes including valleys <br />perpendicular to the flow between two parallel ridges) was required to be about 20 kIn to <br />be rated "good". Barriers rated "poor" were much narrower than that, making it difficult <br />for seeding to result in ice crystal nucleation, growth and fallout before downslope flow to <br />the lee of the barrier results in cloud droplet evaporation and ice crystal sublimation. <br /> <br />7. Proximity to adequate airport <br /> <br />Proximity to an adequate airport was rating on a sliding scale from "poor" to "excellent" <br />based on several factors. To be considered, each airport was required to have an ILS <br />approach and at least one source of fuel. Other factors which were considered included: <br />distance from the target area (ideal was 50 nm or less); probable availability of hangar <br />space; frequency of airport closures due to storms; maintenance and support facilities; and <br />presence of an adequate alternate airport within reasonable distance. <br /> <br />8. Societal opposition <br /> <br />The probability of strong local opposition is not known for several of the potential areas. <br />However, it is known for several others based on conduct of past or current seeding <br />experiments or operations. For example, no strong opposition has surfaced during many <br />years of operational seeding in the Utah areas with the exception of concerns about <br /> <br />9 <br />