Why is it so often cloudy here but not across the mountains?
Proximity to the Pacific ocean is part of the story, but not the whole story. As the cool, moist ocean air moves inland, it normally is a fairly shallow layer...not thick enough to move over the Cascades. But as the air moves up the west slopes of the Cascades, it cools and condenses, forming even thicker clouds. As that air slides down the east slopes of the Cascades, it warms...evaporating moisture...such as cloud droplets. That's why conditions can be so different!