"I need it to be able to survive high winds while keeping out enough gusts for me to stay warm inside."
dude, a tarp tent cannot survive high winds along the PCT,
and it will not help keep you warm.
Your warmth needs to come from carrying a realistic sleeping bag for the conditions and a shelter that won't be destroyed or blown away by winds. Wet snow is not a pleasant thing when its piled on top of you because your tarp blew away, shredded, or simply collapsed. I suggest that you get some more snow experience elsewhere in a safer place than up on the PCT. From your post it just does not sound like you are experienced enough yet to attempt what you suggest, no offence.