The 8th annual Northwest Pinball & Arcade Show is a volunteer-run non-profit event which takes place June 5th to the 7th at the Greater Tacoma Convention and Trade Center. There will be many pinball tournaments happening all weekend long. You should check out their website because there is a LOT more details to be found there!
Tournament details page: here.
For general details about the whole show (including special events and guests) here is link to their front page: here. They also have a facebook page.