There are a few. First, take a look at these.
You'll need to scroll down to "On Snow warmups."
Then, here are some that I taught at a ski fitness week in Portillo.
Stand and hold both poles in front of you. Step back until your back is flat and your chest is parallel to the snow. Tilt your pelvis and round your lower back, as if you were performing the cat exercise, and then straighten it.
Next, stay in the flat back position. Keep your poles straight out in front of you. Push your hips to the right and to the left.
Now, stand upright. Hold your poles, and glide one leg back, as if you were performing a lunge. Return to center, and then switch legs. Try to make it a continuous movement. Do the same thing going out to the side. Remember: keep your feet in contact with the snow.
Also remember: Stretching is not a warmup!