Sean Patrick McGraw belts out his version of Johnny Cash’s ‘‘Folsom Prison Blues’’ during a concert Thursday at the Jamestown Savings Bank Ice Arena. The free show, part of the Downtown Jamestown Development Corporation’s Riverwalk Concert Series, was scheduled for Brooklyn Square but was moved to the arena due to wet weather. A Dunkirk native, McGraw was a semi-finalist on Nashville Star, has been featured on Country Music Television and is scheduled to open several shows for Toby Keith. The Riverwalk Concert Series will take place every other Thursday until Aug. 27. The next show will be July 16 and will feature Willow Creek.