The water temperature in these streams have been around 37 to 40 degrees so you won't get any action on dry flies but you can use nymphs. We are getting our best trout fishing in mountain streams by fishing the back eddies with a Murray's Caddis Larva size 14. Fish these dead drift on a Murray's Trout Nymph Leader in 5X. These leaders have the Scientific Angler Indicators preinstalled to help you.
For road closures due to weather in the Shenandoah National Park you can always call 540-999-3500, option 1, option 1 for the latest updates. For road closures due to weather in the George Washington National Forest you can call the Forest Service at 540-984-4101.