* WHAT...Heavy snow is possible in the Spring Mountains and Sheep Range. 12 to 24 inches of snow possible for elevations above 7000 feet, with locally higher amounts on the peaks. Winds could gust as high as 50 mph. * WHERE...Sheep Range and Spring Mountains-Red Rock Canyon. * WHEN...From 10 PM Wednesday to 4 PM PST Friday. * IMPACTS...Travel could be very difficult to impossible. Gusty winds could bring down tree branches.