The alto saxophone has recently reestablished its vital niche in modern jazz after years of playing second fiddle to the deeper, more romantic tenor saxophone. The tenor still remains the most popular jazz horn; but the alto's singular, sexy intensity is again in fashion, and you can thank guys like Jim Snidero for making it so. He's a bit of a throwback, really: his resume reads like it was written 35 years ago, when virtually every young altoist had paid his dues in a big band (Snidero played with Toshiko Akiyoshi's) and/or a soul-searing organ outfit (like Jack McDuff's, where Snidero toiled in the early 80s). Snidero, holds to old-style virtues--a sculpted sound, a rhythmic authority, a studied command of the horn (all of which are once again in vogue)--while gracefully applying the complexities of modern improvisation. He recently hooked up with a new label, Ken Music; so far the association has yielded a splendidly popping album of his own (Storm Rising) and notable contributions to new albums by trumpeter Brian Lynch and trombonist Conrad Herwig (band mates from his days with Akiyoshi). On Snidero's Chicago stopover, an added bonus is pianist Jim McNeely, who--having finished his own short trio gig this week--will head up the rhythm section for this impressive one-nighter. Tonight, Bop Shop, 1807W Division; 235-3232.