From an old slide. This looks like fog - it isn't, it's drifting snow blowing past at about 30 knots, with visibility steadily becoming worse. In full blizzard conditions visibility can drop to five metres or less. This already is "whiteout" though, with light bouncing between the white sky and surface: so shadows disappear, distances become almost impossible to estimate, and you fall over unseen sastrugi (with no shadows there's nothing to define it). Time to head indoors and wait for things to improve.