Blues Chaos Theory: Burnside and Kimbrough file absentee albums

"OH SHIT, I can't see," said the great Mississippi hill-country bluesman R.L. Burnside as he stepped toward the microphone – just loud enough that it shot through the sound system. Moments before he got on stage at the Sunflower River Blues & Gospel Festival last month, the sky above Clarksdale, Mississippi had turned a mean purple-and-black, and the air started swirling, tossing dust, plastic beer cups, and barbecue sandwich wrappers into little tornadoes that blinded and stung.