Dunnam, 57, was last seen Tuesday in a section of the Appalachian Trail, PA State Police say.
Particularly, Dunnam was near Chimney Rocks between the Deer Lick Shelter and the Rocky Mountain shelters when he was last seen, authorities said.
He was wearing a gray shirt, blue hiking pants, carrying a green backpack and two trekking poles, state police said.
If seen, call 717-249-2121 or 911.
Click here to follow Daily Voice Parsippany-Troy Hills and receive free news updates.