The correct description of the rain shadow effect in Washington State is:
"Moist air from the Pacific Ocean rises over the Cascade Mountains, cools, and releases rain on the western side, leaving the eastern side dry."
This phenomenon occurs because as moist air ascends the mountains, it cools and condenses, leading to precipitation on the windward side (western side) of the Cascades. By the time the air descends on the leeward side (eastern side), it has lost much of its moisture, resulting in drier conditions.