A storm that parked itself over Southern California for days, unleashing historic downpours that caused hundreds of landslides, is moving out of the region after a final drenching. The system dumped a last load of heavy rain over the region Wednesday evening. The National Weather Service also said there were reports of a possible tornado in Pismo Beach and Grover Beach on the central coast. Winds toppled trees and power lines and tore up asphalt. The storm was expected to move out of the area Thursday but authorities say it leaves behind the threat of dangerous mudslides because soils are saturated.