Funny, someone asked this on Facebook too. There is a page you can check any time you wonder about half-staff flags – it shows what the governor has ordered, and why. Today’s flag-lowering was in memory of the military plane crew who died on the other side of the state a few days ago:
http://www.governor.wa.gov/office/flag/default.aspx
Note that you can even sign up to get e-mail when there is a flag-lowering order … TR