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<br />OOll1l27 <br /> <br />Simulated Augmentation of Snow Amounts <br /> <br />The simulation model can compute snow removal costs for a variety of <br />augmentation scenarios. For this study we augmented by 25 percent recorded <br />snow amounts in a random sample of one-third of the stODIIS in each winter <br />examined. StODIIS were defined by snow of at least .1 inch. We chose 25 <br />percent because it is the overall increase in precipitation identified by <br />Mielke et al. (1981) in their reanalysis of the Climax experiments; we chose <br />to augment one-third of the stODIIS because the meteorological conditions for <br />which seeding is thought to be effective were observed on 34 percent of the <br />non-seeded experimental days during the Climax experiment (Chappell, 1970). <br />This augmentation scheme resulted in increases in seasonal snowfall which <br />ranged from 4.5 to 9.7 percent (see Tables 2 through 12). <br /> <br />The largest stoDIIS--those with snowfall greater than the 95th <br />percentile of long-term 24-hour amounts--were not augmented. Snow produced <br />by these storms ranged from 6.5 inches at Rifle to 10.0 inches at Silverton. <br />These upper limits were chosen because safety precautions set forth in <br />state-<]raI1,ted weather modification permits usually curtail seeding of the <br />largest stoDIIS.* <br /> <br />Deciding what expenses to attribute to augmented snowfall is difficult <br />because maintaining highways requires a complement of people and machines <br />whether or not seeding takes place. Also, since snowfall often varies each <br />winter by IlDre than 10 to 20 percent--the amount of additional snow per <br />season that some scientists estimate seeding could produce--and since seeding <br />is less likely in winters of heavy snowfall, it is not clear that counties <br />equipped to handle natural stODIIS l>Ould need more people and equi!;fllent to <br />handle augmented stODIIS. Pdditional snow is, however, likely to require <br />employees (and machines) to spend additional time on the road. We estimate <br />the cost of removing snow produced by seeding by estimating employee and <br />machine expenses of this additional effort. <br /> <br />*For example, permits granted in 1982 for seeding in the Colorado mountains <br />specified that seeding be curtailed when heavy precipitation that could <br />contribute to avalanches or severe weather conditions was occurring or <br />predicted. <br /> <br />-14- <br />