Parts of West Virginia were digging out from up to three feet of snow dumped in the aftermath of Hurricane Sandy, a deluge that cut power to hundreds of thousands of residents and shut down main highways.

The thick blanket of snow at higher elevations across the ridges of the Appalachian Mountains, including in parts of Maryland and Pennsylvania, also brought concerns that rivers and creeks in low-lying areas could flood later in the week as the snow melts, with temperatures expected to reach 60 degrees. Falling trees and...