I work in Western Washington but my bug out location is in Eastern Washington, I work until Tuesday.
Like would the blackout be so bad I can't drive my car? I have my BOB and other essentials on me at all times. My current plan is that if the blackout happens I am hitting the road immediately.
Keep gassed up at all times, keep some in a can to top off before you leave. Get a real map, figure your back routes. Honestly, Snowqualmie will be a bottle neck if there are tons of people leaving. Check all pass statuses as often as you can, pick the one that is clear but less used, even if it might take longer. Reasonably, you will be ahead of the pack simply because you are looking for the exit way before anyone else will be. You should be ok.