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A blizzard is a severe winter storm condition characterized by low temperatures, strong winds, and heavy blowing snow. Blizzards are formed when a high pressure system, also known as a ridge, interacts with a low pressure system; this results in the advection of air from the high pressure zone into the low pressure area. The term blizzard is sometimes misused by news media to describe a large winter storm that does not actually satisfy official blizzard criteria. The origin of the word "blizzard" is believed to be a German settler describing a storm to an Estherville, Iowa, newspaper reporter in Marshall, a small town in southwestern Minnesota.^[1]

Even though some areas are far more likely to experience blizzards than others, it's possible for a blizzard to occur in any location where snow falls. In North America, blizzards are particularly common to the Northeastern quadrant of the United States, Atlantic Canada and the Canadian prairie provinces. In this region of the world, it is not uncommon to experience two or even more blizzards during a winter. Blizzard conditions also occur frequently in the mountain ranges in western North America, however due to these regions being sparsely populated they are often not reported.

Because the factors involved with the classification of winter storms are complex, there are many different definitions of the word blizzard. A major consensus is that in order to be classified as a blizzard, as opposed to merely a winter storm, the weather must meet several conditions: There must be falling or blowing snow, strong winds, and cold or falling temperatures. What the measurements must amount to for a blizzard to be classified as such depends on where you are. It is also a severe storm, that goes up to 30 mph of wind speed, and the temperature drops below freezing.

According to Environment Canada, a winter storm must have winds of 40 km/h (25 mph) or more, have snow or blowing snow, visibility less than 1 km (about ⁵⁄₈ mile), a wind chill of less than −25 °C (−13 °F), and that all of these conditions must last for 4 hours or more before the storm can be properly called a blizzard.

Other countries, such as the UK, have a lower threshold: the Met Office defines a blizzard as "moderate or heavy snow" combined with a mean wind speed of 48 km/h (30 mph) and visibility below 200 m (650 ft). When all of these conditions persist after snow has stopped falling, meteorologists refer to the storm as a ground blizzard.

In the United States, the National Weather Service defines a blizzard as sustained 35 mph (56 km/h) winds which leads to blowing snow and causes visibilities of ¼ mile or less, lasting for at least 3 hours. Temperature is not taken into consideration when issuing a blizzard warning, but the nature of these storms are such that cold air is often present when the other criteria are met. ^[2]

An extreme form of blizzard is a whiteout, when downdrafts coupled with snowfall become so severe that it is impossible to distinguish the ground from the air. People caught in a whiteout can quickly become disoriented, losing their sense of direction. This poses an extreme risk to the aviation community when flying at the altitude of the storm or navigating an airport, severe ice accretion on the wings may also result.

Sudden blizzards can cause terrible damage like burying cars, trucks, and even a full locomotive under heavy snow.

The Great Blizzard of 1888 paralyzed the Northeastern United States. In that blizzard, 400 people were killed, 200 ships were sunk, and snowdrifts towered 15 to 50 feet high. Earlier that year, the Great Plains states were struck by the Schoolhouse Blizzard that left children trapped in schoolhouses and killed 235 people.

A few years earlier, in 1880–81, was a winter referred to in the Dakotas for many years afterward as the "Hard Winter". Author Laura Ingalls Wilder devoted her book The Long Winter to the telling of that winter's story, a narrative of one successive blizzard after another, and the effects on her family and those around her. The book is only slightly fictionalized, as far as her descriptions of the weather. Her tale of two men from the town of DeSmet, South Dakota going after some wheat rumored to be stored some miles south of DeSmet in February of 1881 is true (Ingalls later married one of the men, Almanzo Wilder). It was speculated at the time that if the two men had not found and brought back the wheat, the residents would have starved before the eventual thaw in April of 1881 which allowed the railroads to resume service. The snowbound locomotive pictured above was photographed on March 29, 1881 in western Minnesota, not far from DeSmet.

Thirty-four people died during a three-day spring blizzard in March 1920 in North Dakota. Among them was Hazel Miner, a teenager who froze to death when she got lost on her way home from her one-room school, but saved her younger siblings by covering them with her own body. Winds gusted up to 70 mph.

The Armistice Day Blizzard in 1940 caught many people off guard with its rapid and extreme temperature change. It was 60 °F in the morning, but by noon, it was snowing heavily. Some of those caught unprepared died by freezing to death in the snow and some while trapped in their cars. Altogether, 154 people died in the Armistice Day Blizzard. Unpredictable storms such as this one can come without much warning, causing damage and destruction to humans and infrastructure.

One hundred five years to the day (March 12) after the Great Blizzard of 1888, a massive blizzard, nicknamed the Storm of the Century, hit the U.S in 1993. It dropped snow over 26 states and reached as far north as Canada and as far south as Mexico. In many southern U.S. areas, such as parts of Alabama, more snow fell in this storm than ever fell in an entire winter. Highways and airports were closed across the U.S. As a wider effect, the storm spawned 15 tornadoes in Florida. When the Storm of the Century was over, it affected at least half of the U.S. population; 270 people died and 48 were reported missing at sea.

This article or section deals primarily with the United States and does not represent a worldwide view of the subject. Please improve this article or discuss the issue on the talk page.

Snowdrifts made driving difficult in the 1977 blizzard in Buffalo, New York

• The Great Lakes Blizzard of 1977
• The Great Blizzard of 1978, which resulted in a atmospheric pressure of 957 mbar (28.28 inHg) in Cleveland, Ohio, the lowest non-tropical atmospheric pressure in the United States history.
• The Northeastern United States Blizzard of 1978
• The Halloween Blizzard of 1991 dumped 28.4 inches (72 cm) of snow on Minneapolis, MN and 36.9 inches (94 cm) of snow on Duluth, MN, both records for snowfall from a single storm for those respective areas, causing $100 million of damage.
• The North American blizzard of 1996
• The Blizzard of 1999
• The North American blizzard of 2003
• White Juan (2004)
• The North American blizzard of 2005
• The North American blizzard of 2006, which set a New York City record for the most snowfall from a single storm

1. ^ Read, Allen (1930-02-01). ""Blizzard" Again". American Speech 5 (3): 232. doi:10.2307/451841. Retrieved on 2007-03-28. 
2. ^ http://www.weather.gov/glossary/index.php?letter=b

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• Large blizzard sweeps through British Columbia, Northern Alberta and Saskatchewan - January 10, 2007 Wikinews Exclusives Original reporting
• Ground blizzard
• Snow
• Thundersnow
• Whiteout (weather)
• Cold wave
• Siberian Express

Wikimedia Commons has media related to:

Blizzard

• Dr Richard Wild Website dedicated to the history, news and facts about heavy snow and blizzards.
• Digital Snow Museum Photos of historic blizzards and snowstorms.
• Blizzards Photo Gallery Photos of huge U.S. snowstorms, plus blizzard survival info — all from AOL Research & Learn
• [1] Environment Canada's definition of Blizzard
• [2] SEVERE Winter Weather Events Excerpts from The Canadian Weather Trivia Calendar