Good news for you, I got one thing I can point out that will help you immensely with the Blizzard effect. There is already conveniently one present in the Dev Kit in the form of a Particle Effect :D. You should check it out and see how you could make use of it!
I’m liking the direction this is going in. Have you considered making frozen over lakes? (UE4 has a landscape demo you could use the landscape materials from) In my opinion there is too much land at the moment for the eye to see and it could really benefit from even some unusable water masses.