Wanted to perhaps clarify the point that Myke Chutter was making on coastal distribution. In the Journal of Raptor Research a couple of years ago there was a nice paper on winter destinations of these birds. Most of the BC birds did in fact head for the coast. However, most of the birds sighted were birds on the California coast, with a few on the Washington and Oregon coasts. In addition to the bird that I encountered in Klickitat County, a fellow biologist also sighted one of these birds near Madras Oregon a few years ago. Both of these paths would be consistent with birds traveling from the Okanogan Valley of BC to the California coast. Thus, even though the final destinations are coastal, you probably are more likely to encounter some of these owls in central Washington rather than coastal Washington.

The article was in: Journal of Raptor Research 44(4):294-299. 2010
Here is the abstract. http://www.bioone.org/doi/abs/10.3356/JRR-09-87.1

You'll need access to BioOne for the full article.

Scott Downes
downess at charter.net
Yakima WA