I like this idea. Except for the snow thing. If you want to make it so you mush through snow, then simply make some hard to move through water with a snow particle.
You can easily make it snow rain or whatever using the environments add-on. So by adding admin only commands to that would trigger it... You would get your product. Though i don't know if it is possible to make admin only commands.
I can do all of this for you except for the actual weather changing.