It's not traditional bluegrass music. In fact, it defies placement in typical music genres.

One thing's for certain. Audiences have taken a liking to what some have labeled "progressive bluegrass" played by the Yonder Mountain String Band.The Yonder Mountain String Band, a Colorado-based trio, has appeared several times in the past at Penn's Peak in Jim Thorpe. They always have a large following.They return for a performance at 8 p.m. this evening. Tickets at the door are $22.Adam Aijala, guitarist and vocalist, said in a phone interview regarding Penn's Peak, "It's pretty. We love it there."This marks the first show of the second half of Yonder Mountain's summer tour.Opening will be Jerry Douglas. "With Jerry, you know you're in for a fun time," Aijala said.Aijala said the two teamed up for a benefit for flood victims recently. "He's really a great person and musician; one of the coolest people we know."He said the formation of Yonder Mountain was the result of "four guys who grew up on rock and roll, and got into blue grass when they were in their 20s."Speaking from his home in Boulder, Colorado, Aijala said, "Pennsylvania really reminds me of the home where I grew up. I grew up in Massachusetts."He initially wanted to be a forester, but found music was actually his first love.He said he converted from rock and roll to bluegrass after learning that the late Jerry Garcia, an idol of his, had once played in a bluegrass band. It piqued his curiosity for the style of music."I listened to punk rock and '80s music," he said, "as well as Clash and The Buzzcocks. Our style is more of a correlation between that kind of bluegrass and the traditional. I think we're in the middle."Despite his rock and roll background, Aijala said one of the highlights of his career was seeing bluegrass singer Del McCoury in concert. McCoury is credited with being an influence of Phish and Donna the Buffalo.He also treasures having the opportunity to perform in the Red Rocks Amphitheater in Colorado as well as the Philmore in San Francisco.The Yonder Mountain String Band has been performing for 16 years and is currently working on a new album. He said the goal is to have it completed by January.Aijala said, "Our main goal is to just continue playing. We would love to play in Australia. We have played in Japan and throughout most of the world."In 2008, the band was invited to play at the Democratic National Convention.Other upcoming Penn's Peak concerts are as follows:Deck Party• Aug. 28 - Jake Kaligis - New Constitution, 6:30-9 p.m.ConcertsAugust• 21 - Yonder Mountain String Band, 8 p.m. Tickets $22 day of show.September• 5 - Winger and FireHouse, 8 p.m. Tickets $24 advance and $29 day of show.• 13 - Ana Popovic, 8 p.m. Tickets $22 advance, $27 day of show.• 26 - Uriah Heep, 8 p.m. Tickets $22 advance, $27 day of show.October• 18 - Tommy James & the Shondells, 8 p.m. Tickets $33 and $38.• 31 - Robin Trower, 8 p.m. Tickets $27 advance, $32 day of show.November• 1 - The Tubes, 8 p.m. Tickets $18 advance, $23 day of show.• 2 - Engelbert Humperdinck, 7:30 p.m. Tickets $37 and $47.• 13 - Martina McBride, 8 p.m. Tickets $45 and $55.• 26 - Dark Star Orchestra, 8 p.m. Tickets $24 advance, $29 day of show.December• 20 - Kenny Rogers Christmas & Hits with Linda Davis, 8 p.m. Tickets $65 and $55.February• 13 - An Evening with Dennis DeYoung and music of Styx, 8 p.m. Tickets $34 and $39.• 27 - Creedence Clearwater Revisited, 8 p.m. Tickets $42, PIT $47.Luncheon Shows• Oct. 7, 8, and 9 - The Swing Dolls- A Musical Tribute to the USO.• Oct. 14 and 15 - The Four Freshmen.• Oct. 22 and 23 - Bill Haley's Comets.• Oct. 28, 29, and 30 - Real Diamond.• Nov. 5 and 6 - The Glenn Miller Orchestra.