Blizzard

For other uses, see the winter storm condition.

A blizzard is a severe winter storm condition characterized by low temperatures, strong winds, and heavy blowing snow. Blizzards are a giant storm of 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.

Geography

Some areas are more likely to experience blizzards than others, but blizzards may occur anywhere there are 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.

Worldwide, blizzards often occur across Russia, and into the northern reaches of Europe. They have also been known to occur across the United Kingdom, although severe winter storms there are less common due to the maritime influences of the Northern Atlantic Ocean.

Definition

thumb|left| Blizzards are associated with dangerous road conditions. 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. . Temperatures are generally below 0 degrees F.

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" lies with its use, by O.C. Bates, to describe a brutal snow storm that lashed the open prairie. Bates was the Editor of the Estherville, Iowa newspaper the Vindicator and he couldn't think of a word forceful enough to describe the late blinding snow storm in April of 1871. So "blizzard" was given meaning from that day forward.(Esther's Town-Deemer Lee-Iowa State University Press-Ames 1980-Page 28-Paragraph 3.)

Whiteouts

Although the word is commonly used to describe heavy snow and high winds, this is not a true "whiteout". Real "whiteouts" occur mostly in the Arctic and Antarctic during the spring, when snow is still deep on the ground and there is lots of daylight and surprisingly calm weather and excellent visibility. Whiteouts occur when rays of sunlight are bounced in all directions between bright white clouds, especially a thin layer of overcast and bright snow or ice. Clean snow and ice reflects nearly 85% of incoming light. Falling snowflakes, suspended fog droplets or ice particles in the air would make conditions even worse. In a true whiteout, neither shadows, nearby objects, landmarks, nor clouds are discernible. All sense of direction, depth perception and even of balance may be lost. Land and sky seem to blend, and the horizon disappears into a white nothingness. Whiteouts trick pilots and travellers into believing down is up and thinking far is near.

Notable blizzards in the USA

A snowbound locomotive, photographed on March 29, 1881, in western Minnesota.

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 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 United States areas, such as parts of Alabama, more snow fell than in any averagely recorded winter. 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 a quarter of the U.S. population; 270 people died and 48 were reported presumed dead at sea.

The Blizzard of ’77 was a deadly blizzard that hit Buffalo, New York and the area around it in New York and Ontario (and to a lesser extent, surrounding regions) from January 28 to February 1, 1977. Daily peak gusts of 69, 51, 52, 58 and 46 miles per hour (111, 82, 84, 93, and 74 km/h) were recorded during this period at the Buffalo National Weather Service office (National Weather Service Buffalo Office 2006a).

In the hardest struck areas snowmobiles became the only viable method of transportation. In Western New York and Southern Ontario, snow built up on frozen Lake Erie and the snow cover on the ground over land at the start of the blizzard provided ample material for the high winds to blow around into huge drifts. The combination of bitter cold, high winds, and blowing snow paralyzed the areas most strongly affected by the storm. Lake Ontario was not frozen, which meant that northern New York did not have to deal with previously accumulated snow blowing off the lake’s surface. This did allow for considerable lake effect snow to occur, that when coupled with the existing snow cover and wind also created paralysis.

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