to me, Snark is a mean comment intended to not further the discussion in a positve way, ususally to derail it.
satire would be less mean, ususally just trying to be funny.
Spamalot= satire. weird al = satire
yo momma comments = snark. Ad hominum attacks = snark
Sarcasm tends to be snarky, since it does not further the debate and it ususally can be taken as insulting, one way or another, but is funny, at least to the teller.
Satire I believe is at least intended to be obviously a joke, and should be harder to take offense at. So do lumberjacks take offense at the "I am a lumberjack" song by Monty Python? maybe. is it obvious it is just a joke, and that Monty Python did not mean to offend them? I think so.
Parsing someone's words to find something to be snarky about while ignoring most of the content of their post? not satire. My opinion anyway, eh?