RIVERDALE -- Fifty-five police cars raced down Riverdale Road in the snow early Saturday morning, all with sirens blaring and lights flashing. They converged on the Riverdale Walmart, making onlookers wonder what crime or emergency had occurred. "We like to stack them up and make a lot of noise," said Weber County Sheriff's Cpl. Josh Guard. "I always forget my ear plugs."The law enforcement officers from Riverdale, Pleasant View, Roy and the Weber County Sheriff's Office emerged from their cars with their pint-sized passengers, while Bonneville High School students, Walmart associates and Santa himself waited inside to greet them.