If you did not already, try over exposing 1 stop when shooting snow. I generally use 2/3 or one stop over exposure compensation & often end up boosting a bit more in post.
Yep, you'll need to use the manual settings, semi-auto settings, or exposure compensation settings.
The reason Ron suggested that, is because the camera's light meter is calibrated to render images 18% gray, which leaves predominately white scenes, like snow and wedding dresses, look 18% gray.