You're a mental bastard why would you want her snowboarding with you?! No peace and quiet, yapping in your ear on the lift, slowing you down on the slopes and no doubt complaining about everything from sun in her face and snow in her vag.
Do the right thing bud, tell her theres a change of plans.. hand her the tea towel send her to the kitchen and tell her to have the fucking dinner ready by the time you're back from shreddin with the fellas or she'll be getting your 160 powder deck round her coupon!
Strange, with a post like that I sort of picture you to be the butch and therefore know what the more feminine side likes. By butch I mean the type with anus sized hoops in her ears, spiky hair, body shaped like a pear and a mustache.
As an FYI I dont expect my GF to make dinner because she knows exactly where it hangs.