Sweet Jesus! Where is that mark???

[Cap'n Basch]

Actually, you're supposed to follow a designated path from Mt. Bur-Ominsace (use a chocobo). I'm not positive what the path is, but as long as you follow it through the map, the blizzard will continue. If it stops, you need to talk to that Viera again.

First I've heard of this.

I do know the blizzard is one of the game's "random" weather events, and the Feywood/Rift trip will trigger it while leaving you close enough to get to Fafnir without it stopping. That's how I did that hunt.