Over a period of 2 Weeks that I was in contact with Deakin University I had been creating a Snow Environment as to their request.
Here is my current project:
As shown in this small .gif is that the terrain is deforming from the player and accumulating from the snow particles.
As shown in this .gif the snow is accumulating on the objects; this is done with a snow shader which tessellates from a height map. When the snow hits the object it ray casts towards the collision and draws on the height map with Texture2D.SetPixels(x,y).
In this gif you can see I have been also playing around with some Distortion Shaders which were going to be added when the temperature could cause some mirage effect (which is known as the refractive index).
Source Download: Download
1 to remove the terrain height.
2 to add some terrain height.
Note that the Unity Version used is 5.6.1f1 otherwise the shaders will not work.
Also note that the project is not final, it is a WIP and is all subjected to change in the future; also the Ethan has some odd interactions with the terrain due to the default player controller.
Update 11/10/2018: After reflecting on this project for some time I have decided this is an incorrect way to approach this, and thus should be done using a shader on a plane/mesh collision, doing this will allow the user to not be affected by the deformation and as such allows a smoother transition.