Here's the issue. If you use a built-in meter, your camera is going to try to read the entire scene as 18% gray so you get washed out whites.
There are three solutions:
Get an incident meter and hold it pointing towards the lens axis and take a reading. That will render everything in the proper place provided the light where you are doing this is the same as falling on the scene you are taking a picture of.
The other solution is to recognize that the camera's meter is doing that and open up between 2 stop and bracket around that
The last solution is to meter off a grey card. Put it down in the snow, fill the frame with they gray card and then meter. Hold the meter so its not changed, look up and recompose. Take the photo and you are set.