mmm, that's not good. I haven't biked this intersection from that exact direction before-- would you basically follow Avalon north a little more and turn left on Spokane (or bump up onto the little bit of Alki trail and use the crosswalk to Spokane), which turns into 30th?

I think it would be good to pester SDOT about this; I think their map is wrong. I'll keep this in mind to investigate sometime and see if I agree with your assessment of this intersection, in which case I'll join you in bothering SDOT until they at least update their official route map