The National Weather Service has placed over 470 miles of the AT under a Winter Storm Warning. This area stretches from Springer Mountain, GA up to, and past, Damascus, VA. Hikers already on the trail are urged to take shelter and stay there until the storm passes, and hikers who have not yet begun their hike are warned to postpone their plans until the weather clears.
http://www.weather.gov/
http://www.spc.noaa.gov/products/md/md0100.html
The Great Smoky Mountains National Park has been so hard hit by previous storms that all roads in the park have been closed for days with only sporadic, short-term openings.
UPDATE: Effective 12 NOON 27FEB2015 This Warning Has Been Canceled