* WHAT...Light to moderate valley snow and heavy mountain snow. Several inches of accumulation below 7,000 feet, including 5 to 8 inches in Stanley and Ketchum. One to two feet accumulation above 7,000 feet, including two feet on Galena Summit. Wind gusts as high as around 45 mph. * WHERE...Big Lost Highlands/Copper Basin, Frank Church Wilderness, Sawtooth/Stanley Basin, and Sun Valley Region. * WHEN...From 5 AM Thursday to 5 AM MST Saturday. * IMPACTS...Travel could be very difficult to impossible. The hazardous conditions could impact the Thursday morning and evening commutes. Gusty winds could bring down tree branches.