Current questions and answers regarding the map editor.

Take a texture from some terrain that isn't used on your map (there are sometimes textures like that, which it's unclear why they're needed, for example, emerald-colored grass) and create a mod to recolor it into snow. Well, this is if there really isn't any snow there, otherwise, maybe it's just lying around somewhere? Another option: perhaps it's possible to add textures to the game, rather than replacing existing ones. Although, I haven't checked this.