* WHAT...Snow expected. Total snow accumulations between 2 and 4 inches above 6000 feet; between 4 and 8 inches above 7000 feet; between 8 and 16 inches above 9000 feet. * WHERE...Sheep Range and Spring Mountains. * WHEN...From 4 PM Monday to 10 PM PST Tuesday. * IMPACTS...Travel could be very difficult to impossible, particularly along State Route 156...157 and 158.