A Simi Valley woman was found dead after she apparently drove 200 yards off Tioga Pass Highway at Blue Slide east of the entrance to Yosemite National Park.Roberta Singer, 20, was reported missing to the Mono County Sheriff's Office Dispatch at about 11 a.m. Tuesday.She was last reported on Highway 120 down Tioga Pass.Investigators found her vehicle about 200 yards off the roadway.The Lee Vining Fire Department, Mono County Paramedics, California Highway Patrol, Mono County Sheriff Search and Rescue, Yosemite Search and Rescue, U.S Forest Service, the National Park Service and Caltrans were dispatched to aid in the efforts to …