Alison Krauss is to bluegrass what Winona Ryder is to Hollywood: a 19-year-old former prodigy who is no longer merely good for her age but has emerged as one of the top talents in her field. Friday night at the Wolf Trap Barns, Krauss and her band Union Station avoided the common bluegrass trap of flashy speed shows and emphasized instead the pleasures of melody, harmony and storytelling.

Krauss, dressed in black jeans and a black shirt, was very quick-fingered at times on her fiddle, but she always had a natural, unstrained feel and she specialized in long, carefully shaped notes. Even better were her vocals, which used tender, understated phrases to set up forceful note-bending climaxes. Among the evening's highlights were two songs from her album due out this summer -- Marshall Wilborn's "Wishing Well Blues"and Sidney Cox's "Last Love Letter" -- a pair of heartbroken laments that Krauss sang with a wounded ambivalence far beyond her years.

The latest Union Station lineup includes banjoist Alison Brown, guitarist Tim Stafford, mandolinist Adam Steffey and bassist Barry Bales. The blond-banged Brown, also dressed all in black, played an original new-grass instrumental from her own album on Vanguard, "Simple Pleasures." Newcomers Stafford, Steffey and Bales are from the east Tennessee bluegrass band Dusty Miller; not only were all three fine pickers but Stafford and Steffey proved capable lead singers too.