No, not that sophisticated. Actually is so simple that you might laugh when you know it.
I made two models. The first one is responsible for the snow flakes falling down, where each flake is an object with position and velocity, and the wind applies some more or less random acceleration. The second model is responsible for the piled snow, where each snow crystal is just a white pixel in a picture, and the gravity is implemented by checking for each pixel if there is an empty pixel below (or below-left or -right). And when a snow flake hits a snow crystal then it will be converted into a crystal itself.