US players are currently being dumped into the Oceanic data center every time they zone into an instance. This is crippling the ability to raid tonight. Twitter is non-responsive. Technical forums non-responsive.
Very easy to see and diagnose. Steps to reproduce.
Be on a character that normally connects to Chicago data center.
Be outside an instance, check your connections WoW is making with something like TCP View from Sys Internals. You will see normal Chicago connection.
Zone into a raid (BoD, Nylotha, etc)
Check your connections again, you will now see you are connected to Singapore aka Oceanic IP 188.8.131.52. Congrats on your unplayable latency.
Seems like something in the network infrastructure is busted and is not spinning up new instances in the Chicago datacenter.