Have you noticed a bit of haze in the air and some really nice sunsets the last few days? Apparently it's smoke coming all the way from Siberia. Cliff Mass at the University of Washington provides a nice summary of what's happening:
http://cliffmass.blogspot.com/2015/04/siberian-smoke-reaches-northwest.html
More discussion plus some amazing photos here:
http://www.komonews.com/weather/blogs/scott/Smoke-from-Siberian-wildfires-turns-Northwestern-sunsets-a-fiery-red-300586451.html
And the "Smog Blog" discusses it in the April 19th post.
http://alg.umbc.edu/usaq/
