The rubber tracks (3) allow the Viking to travel over soft terrain such as desert, snow or mud because its load is evenly distributed over all four tracks, all of which are driven.
The snow comes across the Great Salt Lake Desert, hits the Wasatch mountain range and gets pushed up and turned into light, but consistent powdery snow.
Chicago is dealing with a foot and a half of snow, freezing rain is falling in the Northeast and the wind chill is in the 20s here in the Sonoran Desert.