* WHAT...Heavy snow expected. Total snow accumulations 12 to 24 inches, with 24 to 30 inches in Crater Lake National Park. Winds gusting as high as 50 mph over high and exposed terrain. * WHERE...The southern Oregon Cascades north of Howard Prairie Lake, and the eastern Douglas County Foothills above 3000 ft, including the passes along highways 140, 62, 138, 230, and 58. * WHEN...From 5 AM Wednesday to 5 PM PDT Thursday. * IMPACTS...Travel may be very difficult to impossible. The hazardous conditions could impact the Wednesday morning and evening commutes. Gusty winds could bring down tree branches. * ADDITIONAL DETAILS...The heaviest snow is expected Wednesday afternoon when 1 inch per hour rates are a near certainty, and there is a 60 to 80% chance of 2 inch per hour snowfall rates for a couple of hours during the main frontal passage.