According to the National Weather Service, a blizzard is defined as a storm accompanied by heavy snow and/or blowing snow creating whiteout conditions. Sustained winds are at least 35 mph, creating considerable drifting snow near roads, in open areas, and around buildings. Blizzards usually form on the northwestern edge of strong low pressure systems. The distance between the core of the strong low pressure and the nearby high pressure system allows pressures to become tight. Hence, strong winds form, and in addition to the snow that is falling or already on the grow, they create extremely dangerous travel conditions. The snow cover on the ground can drift significantly, the falling snow can be responsible for visibilities near zero, and hazardous wind chills are often observed.
*When the Word 'Blizzard' Received Its Name
The term 'blizzard' was first mentioned from an Iowa newspaper to describe a snowstorm in the 1870s. Before that point, 'blizzard' was normally defined as a canon shot or a volley of musket fire. By the next decade, in the 1880s, the word 'blizzard' became widespread among the United States and England.
*Where Do Blizzards Occur?
Blizzards can happen where there is plenty of snow observed in a winter season. In the United States, they are more likely seen in the upper Midwest and the Great Plains, where there are plenty of flat lands in those regions. The open areas without obstructions like large trees allow the strong winds to keep their strength and blow the snow around.
*The Danger of Blizzards
Hazards from blizzards include extreme wind chills, heavy snow, and strong winds. In areas with very dry air, snow is easier to be blown around caused by gusty winds. Even when it's not snowing, the heavy snow pack on the ground combined with the winds can reduce visibilities to less than a quarter of a mile. Roads often become impassible because of the drifting snow. And the strong winds that blow are likely to create dangerously low wind chills. Therefore, people are advised by a local law enforcement agency to avoid venturing on roadways during blizzard events.
Blizzards are dangerous storms. People are strongly encouraged to avoid traveling in them. In case you experience a blizzard at home, be sure you have plenty of food and a good shovel handy. As for travel, keep a winter survival kit (i.e. blanket, small shovel, cloth, candy bars) in the trunk of your car, and make sure your vehicle is in a good condition.
National Weather Service - NWS Flagstaff "Blizzards"