[COMPLETED] 5-10 Minutes Account Server Downtime @4pm Pacific 5/24
 

From the announcements thread:

We need to roll out an emergency update to our account server. We will be proceeding with this at 4pm Pacific, and expect it to be down for 5-10 minutes. During this update, new logins to Realm Works and Hero Lab Online will be unavailable, but your service will be unaffected if you are already logged in. We apologize for any inconvenience.

UPDATE: This has been completed.