Guitarist Carlos Johnson is a fleet-fingered picker who wraps a shimmering B.B. King-like timbre around asymmetrical melody lines; he augments this breezy virtuosity by laying sharp staccato notes amid his leads to keep things from getting too smooth. Johnson's repertoire runs the gamut from jazz classics like Ellington's "Take the 'A' Train" to original compositions often based on time-tested blues standards (his "Leavin' on the Next Train' is an emotionally charged variation on "Goin' Down Slow" as interpreted by Bobby "Blue" Bland and, later, Junior Wells). Johnson sometimes seems a bit too enamored of his own prowess: he'll tear through a medley of a half-dozen songs, each one packed with dazzling displays of technical virtuosity, without lingering on any idea long enough to explore its emotional and musical implications. But his commitment to the entirety of the modern blues tradition is unassailable; if he can find the maturity and the confidence to slow down and immerse himself in the meaning as well as the technical challenge that lies at the heart of blues improvisation, he could blossom into one of our most exciting contemporary talents. Friday, Saturday, and Tuesday, Rosa's, 3420 W. Armitage; 342-0452.