I am on mail in probation until MAy 2013, they can still call me in to do a drug test. I want to hike the appalachian trail starting Feb 20th. What are the chances of them Calling me in in the state of georgia?

Drug tests are random. They can call you in anytime they want. If your charges were drug related, they may do it more often. If you haven't gone in for one recently, then the chances would appear higher.