A request: When you've picked up the Crux of Fire there's nothing in your journal that tells you to take it back to Korren.
He probably told you, but there will generally be a lot of game time between setting out for the Crux of Fire and finally laying your hands on it, so a note to help your memory would help. It would be helpful if, on picking up the Crux, a message in your journal would appear, saying something like 'You've successfully acquired the Crux of Fire. Korren has asked you to take it back to him as part of the final contingency plan.'
When you do return with the Crux to him there is an experience award, so also this makes a quest note in the journal logical.
Like someone else (and I can't remember who it was), I was able to get it to "snow" in Raven's Gate (East) by quick-traveling from Durnore. Now, I don't know if it's supposed to snow in Raven's Gate (East) or not (I don't think it is).
At least that's not unnatural if it's happening outside, but I've had it inside
Raven's Gate, which is more odd. I believe that was after quick travel as well.