From the Smokies website

Storm Damage Closures
On Thursday June 13, 2013 a major thunderstorm produced heavy rains, high winds and a possible tornado in portions of Sevier and Cocke Counties in Tennessee. The following park facilities are temporarily closed:

Hiking Trails:
Cosby Area: Gabes Mountain Trail and Snake Den Ridge Trail
Big Creek Area: Big Creek Trail and Baxter Creek Trail
Campground Facilities:
Loop B of the Cosby Campground is closed
Backcountry Campsites:
Campsites 29, 34, 36, 37 and 38 are all closed in due to damage incurred during this storm event.

Additional trails and facilities may be added to the closure list as the damage assessment continues.

Also this from yesterday:

A North Carolina National Guard helicopter crew tonight airlifted a 53-year-old hiker out of the back country of the Great Smoky Mountains National Park after he broke his ankle when a tree hit him during a Thursday afternoon storm, officials said.

Nathan Lipsom of Cambridge, Mass., was carried out around 6:45 p.m. and taken to Mission Hospital in Asheville, N.C., according to park spokeswoman Molly Schroer.

His condition was not available tonight.

Rangers earlier in the afternoon were working their way toward Lipsom, who suffered a broken ankle at about 4 p.m. Thursday while hiking on the Low Gap Trail south of the Appalachian Trail, Schroer said.

A back country ranger found him Friday morning while patrolling the trails around Cosby and Big Creek to assess storm damage.

A National Weather Service crew confirmed an EF-1 tornado hit the Cosby area during the storm. Damage to the trails around the Cosby and Big Creek areas prevented a ground team from reaching Lipsom in a reasonable amount of time for a carry-out operation, Schroer said.

A team of rangers cut away downed trees on the trail, and another team of rangers followed with a litter.