I'm also in the Greater Seattle area. Yes, the major networks are all broadcast in HD (720p or 1080i depending on the particular network). There area also may 'minor' networks being broadcast, usually in SD, 480i. Check out
http://www.rabbitears.info/market.php for details.
It would be very helpful to see a TV Fool report based on an antenna height of 25' AGL.
Your first post is showing conditions at the default height of 10'. If this is the best available, I would opt for an outdoor mounted Winegard HD7696P or HD7698P pointed north.