A large tree toppled onto Highway 101 Monday, blocking at least one southbound lane and snarling traffic during the morning commute, officials said. The incident was reported about 7:30 a.m. at Highway 101, just south of Cesar Chavez Street, according to the California Highway Patrol. Several right-hand lanes were blocked on the highway and traffic was delayed by about 30 minutes, according to the CHP. A Sig-alert was issued for the area as a Caltrans crew worked to clear the highway.