If you don't want time paradoxes, let me know and I'll rewrite
[Puck has been drifting around aimlessly outside, stalling before having to head inside the Shelter for the night. But ohh, he remembers this lady. Poor her, she really looks like she needs something fun to happen to her.
So right as Vanessa passes under a tree (or close to a building if there are no trees around), all the snow that had gathered on it will fall down on her head. Spur of the moment thing?]