sentences:  It is part of the larger grouping known as the Pacific Coast Ranges that extends over much of the western edge of North America from California to Alaska.The range creates a rain shadow effect for the Willamette Valley that lies to the east of the mountains, creating a more stable climate and significantly less rain than the coastal region of the state.To the west where the range over-shadows the Oregon Coast, the range causes more precipitation to fall on that side of the mountains, contributing to the numerous rivers that flow to the Pacific Ocean.