RIVERSIDE, Calif. -

Thousands of motorcyclists will fall into formation and roar through Riverside and Moreno Valley today, in a 40-mile Memorial Day tribute that will conclude with a patriotic concert.

   The 15th annual West Coast Thunder ceremony is set to begin at 8 a.m. outside Skip Fordyce Harley-Davidson, 7688 Indiana Ave.

   Last year's event drew more than 7,500 riders, according to organizers.

   Motorcyclists will assemble in front of the dealership, between Adams and Winstrom streets, where the ``Star Spangled Banner'' will be sung and remarks offered by Riverside Mayor Rusty Bailey, a former Army officer, and other guest speakers.

   At precisely 9:11 a.m., riders, many of them affiliated with veterans' organizations, will head out on a 10-mile trek to slow roll past the cemetery, with the Inland Empire Harley Owners-West Coast Thunder Honor Guard leading the procession, escorted by Riverside police. Temporary road closures will be in effect along the way to accommodate the motorcyclists.

   The route runs east on Indiana to Arlington Avenue, turns south on Alessandro Boulevard and continues to Trautwein Road, then goes east along Van Burn Boulevard until reaching the cemetery, where some riders will peel off to pay their respects.

   However, for the second consecutive year, many participants will continue past the cemetery and head into Moreno Valley via state Route 60.

   At Frederick Street, the riders will exit the freeway and rumble into  the city, turning east onto Sunnymead Boulevard, where they will travel a mile-long route as part of a veterans' salute.

   ``Considering Moreno Valley's military heritage and affinity, having the city as part of the parade route will significantly enhance the events of the day for Moreno Valley residents,'' said Mayor Tom Owings. ``Moreno Valley is proud to join West Coast Thunder in honoring our true American heroes.''

   Riders will depart Moreno Valley via Heacock Street, re-entering the eastbound 60 freeway and proceeding south to the Soboba Casino in San Jacinto under escort by the California Highway Patrol.

   At 11 a.m., a concert featuring patriotic music will be held at Soboba.  Scheduled performers include The Cadillac Three and country-western singer Rodney Atkins. An ``Ultimate Sacrifice'' color guard presentation is slated for 1 p.m., with a moment of silence, after which the music will resume, featuring  food, drinks and a raffle -- with the grand prize winner taking home a Harley- Davidson Iron Sportster, organizers said.

   Funds from entrance fees go to the Riverside National Cemetery Support  Committee, which relies on donations to build monuments and make other  improvements at the cemetery, where nearly 200,000 U.S. military veterans, police officers, firefighters and others have been laid to rest.

   Close to $400,000 in donations have been made, according to Skip Fordyce, which has organized West Coast Thunder every year since 2000.