Whiteout

Whiteout occurs when the sky and snow assume a uniform whiteness, making the horizon indistinguishable and eliminating the contrast between visible objects both near and far. The observer loses all sense of perspective, and aircraft and other operations become extremely hazardous.

Whiteouts happen most frequently in spring and fall, when the sun is near the horizon. Further conditions necessary to the development of whiteouts are:

• uniform snow cover
• cirrostratus, altostratus or stratus overcast

The sky cover is the most important factor in the development of whiteout conditions and forecasters therefore use the cloud forecast to predict possible whiteouts.