This is the route for the AIDS Walk, Sunday. I believe the actual walk starts at 10am, but not until later will the walkers leave the park and walk up 110th Street to Riverside Drive, from there they will walk to 86th street, and then back east to Central Park.
So I'd say after 10am try not to get a destination in this box. I recall last year being stuck inside this square between 86th and 110th on the upper west side, with the only ways in and out through the park at 79th and 96th. Check the news to see when the walk ends. and ofcourse when it ends you may have a lot of people who want to take cabs home, maybe, or maybe it's not worth it, as they either live close enough to catch a subway, or they have cars parked nearby. I think they will exit from the park at columbus circle.