Under the Weather

Every couple hours at the Froststone Vault there will be an elemental world boss spawn in one of the elemental types. You must defeat 4-5 nearby elementals to remove the boss' shield and then defeat the boss. I've seen it rotate wildly, and got 3 earth storms before my first water so it seems like it may be random. They're marked on the map when you're nearby but I've also included coordinates below.

/way #2151 60.23 38.56 Under the Weather

I don't know if it depends on how fast the boss is killed, but as far as I saw it seems to be exactly every two hours at the full hour.

The event was for me at 5 p.m, at 7 p.m, at 9 p.m and now at 11 p.m. wihout fail.
Please let me know if this is weird regular coincidence or really regularly every two hours :)

edit:
Today the uneven rythm was broken, now the event takes place at the even hours.
Looks like it switched around the WQ reset.

Found THIS great weak aura that helped remind me when this was happening. It's made for EU server but can be changed to NA, just read the comments.