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The most well-known blizzards are winter storms that produce several feet /inches occurring with strong winds that cause blowing snow and whiteout conditions, but not all blizzards happen this way. In the Midwest, ground blizzards develop with little or no snowfall. One of the most infamous ground blizzards was the Children’s Blizzard of 1888, which killed an estimated 235 people in the Great Plains. Since then, there have been countless other ground blizzards, many of which were deadly. Ground blizzards are extremely dangerous because they are preceded by unseasonably warm air, which can cause people to let their guard down. People may venture outside without proper winter clothing. This relatively warm weather does not last long. The ground blizzard occurs when an Arctic cold front moves through the region, causing temperatures to drop and winds to increase, often reaching gusts of 50 to 60 mph. If there are several inches of deep fresh snow on the ground, this strong wind will quickly pick up the snow and create whiteout conditions. Another reason these blizzards are dangerous is the cold temperatures that follow behind the Arctic front. Anyone stranded in their vehicle or forced to walk outside is at risk of frostbite or hypothermia. Ground blizzard refers to a weather condition where loose snow or ice on the ground is lifted and blown by strong winds. The primary difference between a ground blizzard and a regular blizzard is that in a ground blizzard no precipitation is produced at the time, but rather all the precipitation is already present in the form of snow or ice at the surface. Meteorological Criteria While the term “ground blizzard” is often associated with intense blowing and drifting snow conditions, there are specific criteria which must be met. Often such criteria will be determined by a country’s governing weather agency or other similar body. In the U.S, according to the National Weather Service a blizzard is defined as having sustained winds or frequent gusts of 35 mph or more, visibility frequently below 1/4 mile in considerable snow and/or blowing snow, and the above conditions are expected to prevail for 3 hours or longer. Environment Canada similarly maintains that the temperature must be colder than 0°C, widespread reduction of visibility to less than 1 kilometer due to snow and/or blowing snow and sustained wind speeds or gusts of 40 km/h or more, with all these conditions persisting for at least 4 hours (6 hours for the Northwest Territories and Nunavut) Types There are 3 different forms of ground blizzards:
- In horizontal advection conditions, the winds blow across the surface of the earth with very little if any large-scale upward motion.
- In vertical advection conditions, the winds exhibit large-scale upward motion lifting the snow into the atmosphere creating drifting waves of snow up to 500 meters in height.
- In thermal-mechanical mixing conditions, massive convective rolls form in the atmosphere and the blizzard may be observed from space with the blizzards convective rolls creating waves of snow (also known as snow billows) resembling lake or ocean effect snow bands. The extreme conditions can quickly bury a two story home and make breathing very difficult if not impossible if caught outdoors.