If you have any routes through Myrtle Edwards Park, it's best to avoid them until a few days after the event. There are already trucks driving around on the trail, bundles of cable everywhere (they're covered by these things that look like ramps, but slow way down before you ride over one if you don't want to knock your wheels out of true), and tents next to the trail blocking sight lines.
Don't try to drive through Queen Anne or Interbay, either. This weekend I'm guessing.
I never remember when it is (because it doesn't interest me), and Myrtle Edwards is a gorgeous park so a lot of my routes go through it. One weekend every August I get to the park expecting a pleasant and uneventful ride, and it's pandemonium instead.
Words to the wise.