blizzard, winter storm characterized by high winds, low temperatures, and driving snow; according to the official definition given in 1958 by the U.S. Weather Bureau, the winds must exceed 35 mi (56 km) per hr and the temperature 20°F; (-7°C;) or lower. Blizzards are most common in the N Great Plains states—South Dakota is sometimes called "the Blizzard State"—but they also occur as far south as Texas and as far east as Maine.

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.

Geography

Even though some areas are more likely to experience blizzards than others, it is possible for a blizzard to occur in any location where there is snow and high winds. In North America, blizzards are particularly common to the extreme portions of the Northeastern United States, the Northern Great Plains in the United States, Atlantic Canada, and the Canadian Prairie Provinces. Blizzard conditions also occur frequently in the mountain ranges in western North America, however since these regions are sparsely populated they are often not reported.

Definition

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.

In the United States, the National Weather Service defines a blizzard as sustained 35 mph (56 km/h) winds which lead to blowing snow and cause 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 is such that cold air is often present when the other criteria are met.

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 30 mph (48 km/h) and visibility below 650 feet (200 m).

When there are blizzard conditions but no snow falling, meteorologists call this a ground blizzard because all the snow is already present at the surface of the earth and is simply being blown by high winds. Ground blizzards require large expanses of open and relatively flat land with a sufficient amount of accumulated and loosely packed, powdery snow to be blown around.

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.

Whiteouts

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.

Etymology

The Word 'Blizzard' was first used in 1870 during a severe snowstorm in Iowa and Minnesota, by an Estherville, Iowa newspaper. The word has its origins in boxing, referring to a volley of punches in Boxing. The word was first used by the USA signal corps weather service in 1876.

Notable blizzards

The Great Blizzard of 1888 paralyzed the Northeastern United States for several days. 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.

The Midwestern 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 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 averagely recorded in any winter yet. Highways and airports were closed across the United States Of America. As a wider effect, the storm spawned 15 tornadoes in Florida. When the storm was over, it affected at least quarter of the U.S. population; 270 people died and 48 were reported presumed dead at sea.

References

External links

• 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
• Environment Canada's definition of Blizzard
• Severe Winter Weather Events Excerpts from The Canadian Weather Trivia Calendar
• http://www.ussartf.org/blizzards.htm
• http://content.scholastic.com/browse/article.jsp?id=4912