I can't find it at the moment, but it was mentioned in some announcement of the event.
Dragons will appear over the three alliance capitals (Mournhold, Elden Root, Wayrest) and the three starter cities (Dagon's Watch, Vulkhel Guard, Daggerfall) during the event.
I saw a dragon in stormhaven and didn't know anything about an event. I was a bit taken back
The Lord Jesus Christ saved me from sin and darkness. His love has transformed me so that I am a new creature in Him. May you find Him too, and experience His richness and goodness!
The ones that fly around Elden Root are AWESOME. I stand around there a lot waiting for them! Haven't got a screenshot yet - I get too involved in watching to remember!