The warming hut is not accessible by car.  There's a flat trail leading to it from the Shaffer Run Rd parking lot - see the trail map.  To get to Shaffer Run Rd, take Rt 31 to Bakersville.  Do not attempt to use Tunnel Rd to get to Shaffer Run Rd in winter!  

There are also 2 parking lots on Tunnel Rd, but the road will not be plowed beyond the first parking lot.  

North Woods trail map

Laurel Highlands Nordic Ski Patrol patrols this area at weekends.

Winter recreation guide from Forbes State Forest
Forbes State Forest trail map
Forbes State Forest map collection