A native of North Dakota who's lived in Denver since 1990, sweet-voiced Celeste Krenz sings songs that slip between genres. Flavored predominantly with contemporary bluegrass, her music is nevertheless infused with healthy doses of pop tunefulness and folky austerity--a classic example of post-Nashville songwriting a la Nanci Griffith, Iris DeMent, and Emmylou Harris. Krenz isn't at that level yet, but her second album, Slow Burning Flame (Emergency), bristles with promise and in isolated patches achieves sublime beauty. With lead guitarist Bob Tyler and bassist Scott Smith, she transports her soft-hued lyricism and florid melodicism into a variety of settings--some songs are so light they threaten to become airborne, but just as many remain well rooted. Her striking voice can effortlessly navigate the subtleties of a phrase, delicately balancing beauty and agility. Between her decent if imperfect originals and a smart choice of covers, including a swell reading of Dolly Parton's classic "Jolene," Krenz appears poised to cross over to a larger audience--one vaguely intolerant of straight country but unwilling to succumb to the banality of a Sheryl Crow. This marks her Chicago debut. Saturday, 8 PM, Schubas, 3159 N. Southport; 525-2508.