The snow fades in fairly evenly, but melts away with a sharper falloff, and remains congregated in the areas painted on the terrain (these are areas which are in shadow for most of the day)
As you can see, the snow builds on the rocks and trees based on normal direction. The trees are also now linked up correctly to match other season effects.
The level is starting to come together, but this just makes whats missing even more obvious. In this case, falling leaves and snow are clearly missing as the trees shed leaves and snow builds on the ground!