Whiteout (weather)

Whiteout or white-out^[1] is a weather condition in which visibility and contrast are severely reduced by snow, fog, or sand. The horizon disappears from view while the sky and landscape appear featureless, leaving no points of visual reference by which to navigate.

A whiteout may be due simply to extremely heavy snowfall rates as seen in lake effect conditions, or to other factors such as diffuse lighting from overcast clouds, mist or fog, or a background of snow. A person traveling in a true whiteout is at significant risk of becoming completely disoriented and losing their way, even in familiar surroundings. Motorists typically have to stop their cars where they are, as the road is impossible to see. Normal snowfalls and blizzards, where snow is falling at 3 or 5 centimeters per hour (1 or 2 in/h), or where the relief visibility is not clear yet having a clear field of view for over 9 meters (30 ft), are often incorrectly called whiteouts.