A blizzard is a severe snowstorm characterized by strong winds and low temperatures. The difference between a blizzard and a snowstorm is the strength of the wind. To be a blizzard, a snow storm must have sustained winds or frequent gusts that are greater than or equal to Template:Convert with blowing or drifting snow which reduces visibility to 400 meters or a quarter mile or less and must last for a prolonged period of time — typically three hours or more. Snowfall amounts do not have to be significant. In Australia the definition requires that at least some snow has been raised from the ground.
A severe blizzard has winds over
Template:Convert, near zero visibility, and temperatures of −12 °C (10 °F) or lower. A ground blizzard has snowdrifts and blowing snow near the ground, but no falling snow.
Blizzards can bring near-whiteout conditions, and can paralyze regions for days at a time, particularly where snowfall is unusual or rare. The 1972 Iran blizzard, which caused approximately 4,000 deaths, was the deadliest in recorded history.==Storm systems in the United States==
In the United States, storm systems powerful enough to cause blizzards usually form when the jet stream dips far to the south, allowing cold, dry polar air from the north to clash with warm, humid air moving up from the south.
When cold, moist air from the Pacific Ocean moves westward to the Rocky Mountains and the Great Plains, and warmer, moist air moves north from the Gulf of Mexico, all that is needed is a movement of cold polar air moving south to form potential blizzard conditions that may extend from the Texas panhandle to the Great Lakes.
Another storm system occurs when a cold core low over the Hudson Bay area in Canada is displaced southward over southeastern Canada, the Great Lakes, and New England. When the rapidly moving cold front collides with warmer air coming north from the Gulf of Mexico, strong surface winds, a lot of cold air advection, and extensive wintry precipitation occur.
The Dakotas and parts of Minnesota experienced a succession of blizzards in the winter of 1996-1997. As part of the Great Plains, with few trees or other obstructions to reduce wind and blowing snow, this part of the country is particularly vulnerable to blizzards with very low temperatures and whiteout conditions.
In the southern central Great Plains, rapidly intensifying low pressure systems moving out of the Rocky Mountains can cause heavy snows and strong winds to the north, while to the south and east thunderstorms and rain are produced.
* 2011 Halloween nor'easter
* Groundhog Day Blizzard of 2011
* December 2010 North American blizzard
* Third North American blizzard of 2010
* Second North American blizzard of 2010
* First North American blizzard of 2010
* February 2007 North America Winter Storm
* Saskatchewan blizzard of 2007
* Blizzard of 1999
* April Fool's Day Blizzard
* Blizzard of 1996
* Great Blizzard of 1993
* Halloween Blizzard of 1991
* Chicago Blizzard of 1979
* Northeastern United States Blizzard of 1978
* Great Blizzard of 1978
* Blizzard of 1977
* Chicago Blizzard of 1967
* North American blizzard of 1947
* Armistice Day Blizzard of 1940
* Great Lakes Storm of 1913
* Schoolhouse Blizzard of 1888, North American Great Plains
* Great Blizzard of 1888, Northeastern U.S.
*Digital Snow Museum Photos of historic blizzards and snowstorms.
*Farmers Almanac List of Worst Blizzards in the United States
*United States Search and Rescue Task Force: About Blizzards
*A Historical Review On The Origin and Definition of the Word Blizzard Dr Richard Wild