A semi-trailer traveling northbound on County Trunk S in southern Door County caused the highway to be closed for about two hours on Friday afternoon.  Southern Door Fire Chief Rich Olson says the driver of the semi lost control of the truck on the slippery road caused by blowing snow, and it jack-knifed into the ditch.  A heavy-duty wrecker from Green Bay was dispatched to pull the semi-truck out, and traffic was detoured west from Carnot Road to County Trunk J.  The Door County Sheriff’s Department reported that County Trunk S was reopened shortly after 5:30 pm.  No injuries were reported.