Yarn can be a steelhead killer. Yarn can be deadly in fast water with scent on it. Although it might be much easier to use a jensen egg or gooey bob. I find yarn most effective fished by its self is when the salmon are spawning. I will fish the deep holes right below an area of spawning kings, and put a clinic on sometimes with just yarn under a float. I wouldn't see why it wouldn't work good in the PNW cause from what I have heard, fly fishermen to pretty well fishing yarn flies.