I hear that, if I am not mistaken, Cabelas has several tarps also, might want to check out their website.
One good thing about snow, you can brush it off before it melts!
Wish I had more info for you on how long a paratarp could take the rain, like I said, I have put it up quick for a passing storm if I wanted to stay out and hunt and not go into camp, when the storm or shower passes, I went back on stand.
For that short time, it made a pretty good place to drink a cup of coffee from the thermos and eat a bologna sandwich and a can of sardines!
John