This week in Americana The sixth annual 30A Songwriters Festival, scheduled for Jan. 16-18 in South Walton County, FL has announced its first round of artists, including Graham Nash, Indigo Girls, Leon Russell, Jason Isbell, Shawn Mullins, Sara Watkins, Chely Wright, Bobby Bare Jr., Steve Poltz, Angaleena Presley, Over the Rhine, Glen Phillips, Jeffrey Steele, Jesse Harris, Mary Gauthier, Hayes…