Intense, but of limited duration, periods of moderate to heavy snowfall, accompanied by strong, gusty surface winds and possible lightning. A watch is used when the risk of a hazardous weather event has increased significantly, but the occurrence, location and timing are still uncertain. A warning is used for conditions posing a threat to life or property. Advisories are for less serious conditions that cause significant inconvenience and, if caution is not exercised, could lead to situations that may threaten life and property. Whiteouts can occur rapidly often blinding motorists and creating chain-reaction crashes involving multiple vehicles.
Whiteouts are most frequent during blizzards.
As the wind increases, heat is carried away from the body at an accelerated rate, driving down the body temperature. At wind speeds of four mph or less, the wind chill temperature is the same as the actual air temperature. The threshold for potentially dangerous wind chill conditions is about minus 20 degrees Fahrenheit.