To quote Willie Nelson, ain't it funny how time slips away? Twangfest, the city's annual celebration of rock, country and soul music, turns thirteen this year. And while the teenage years are normally accompanied by petulance, angst and clumsy sexual awakenings, this year the roots festival gets back to its, uh, roots with a heavy helping of Americana-indebted acts. Western swing revivalists (and pomade aficionados) Big Sandy & His Fly-Rite Boys headline Thursday's set with creamy steel-guitar work and some rockabilly rave-ups. On Friday, Austin-based septet the Asylum Street Spankers returns to town with its grab bag of prewar blues and Tin Pan Alley-styled song craft. The fest comes to an end on Saturday with a set by ex-Drive By Trucker Jason Isbell and his band, the 400 Unit, capping the event with Southern-rock smarts and country soul. For more information and a full schedule of events, visit http://twangfest.com/2009/schedule.