This is the beauty of T2 right here. The lack of restraint. To properly use the software and make snow like this, the following must be done:
Remember that no longer is the world, surfaces, and terrain seperate entities.
Remember that the terrain "group" isn't the only place terrain can change shape.
Remember that displacement is more then just overhang.
T2 has effective changed the way we think about building a scene, that's what makes it so great.