Ground blizzard

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A ground blizzard in Ontario, March 21st, 2004 Ground blizzard.JPG
A ground blizzard in Ontario, March 21st, 2004

Ground blizzard refers to a weather condition where loose snow or ice on the ground is lifted and blown by strong winds. [1] This can occur in the absence of precipitation, and can even occur when the sky is clear. This is in contrast to "ordinary" blizzards, which are accompanied by heavy falling snow. They can be especially dangerous as they occur after a winter storm has passed, when it is assumed that all forms of severe winter weather has ended. [2]

Weather Short-term state of the atmosphere

Weather is the state of the atmosphere, describing for example the degree to which it is hot or cold, wet or dry, calm or stormy, clear or cloudy. Most weather phenomena occur in the lowest level of the atmosphere, the troposphere, just below the stratosphere. Weather refers to day-to-day temperature and precipitation activity, whereas climate is the term for the averaging of atmospheric conditions over longer periods of time. When used without qualification, "weather" is generally understood to mean the weather of Earth.

A winter storm is an event in which varieties of precipitation are formed that only occur at low temperatures, such as snow or sleet, or a rainstorm where ground temperatures are low enough to allow ice to form. In temperate continental climates, these storms are not necessarily restricted to the winter season, but may occur in the late autumn and early spring as well. Very rarely, they may form in summer, though it would have to be an abnormally cold summer, such as the summer of 1816 in the Northeastern United States.

Contents

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. [3] Environment Canada similarly maintains that widespread reduction of visibility to less than 400 meters due to snow and/or blowing snow and sustained wind speeds or gusts of 40 km/h or more must be present for at least 4 hours (6 hours for the Northwest Territories and Nunavut) [4]

Types

There are 3 different forms of ground blizzards:

  1. In horizontal advection conditions, the winds blow across the surface of the earth with very little if any large-scale upward motion.
  2. 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.
  3. 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.
    Strong advection rolls during a ground blizzard in North Dakota, January 15th, 1997 Blowing snow.gif
    Strong advection rolls during a ground blizzard in North Dakota, January 15th, 1997

Climatology

Ground blizzards occur throughout the world, however unlike other winter storms, topography either aids in their formation or prevention. The most important topographic element in a blizzard is the requirement for a vast amount of large open and relatively flat land. Any type of flora, especially coniferous forms, will catch any drifting snow significantly reducing the blizzards effects.[ citation needed ] The environment must also support temperatures cold enough to prevent any snow on the ground from melting and bonding the ice crystals together.

Topography The study of the shape and features of the surface of the Earth and other observable astronomical objects

Topography is the study of the shape and features of land surfaces. The topography of an area could refer to the surface shapes and features themselves, or a description.

Ground blizzards are common in the American great plains in the wake of snowstorms producing light, dry snowfall that is more easily picked up by strong winds. [2] They are also common in the Canadian Prairies, Siberia, Northern China, and also Arctic and Antarctic regions during seasonal transition periods, such as the spring and fall.

Canadian Prairies geographical region of Canada

The Canadian Prairies is a region geographically located in Western Canada. The area includes the Canadian portion of the Great Plains and the Prairie provinces such as Alberta, Saskatchewan, and Manitoba. These provinces are partially covered by grasslands, plains, and lowlands, mostly in the southern regions. Known to a lesser extent, is the northern-most section of the Canadian prairies which is marked by forests and more variable topology. To define the region in a physiographic sense, to strictly include areas only covered by prairie land, the corresponding region is known as the Interior Plains. Geographically, the Canadian prairies extend to northeastern British Columbia, however this province is not included in a political manner.

Famous ground blizzards

Related Research Articles

Blizzard type of snowstorm

A blizzard is a severe snowstorm characterized by strong sustained winds of at least 35 mph (56 km/h) and lasting for a prolonged period of time—typically three hours or more. A ground blizzard is a weather condition where snow is not falling but loose snow on the ground is lifted and blown by strong winds. Blizzards can have an immense size and usually stretch to hundreds or thousands of kilometres.

Lake-effect snow

Lake-effect snow is produced during cooler atmospheric conditions when a cold air mass moves across long expanses of warmer lake water, warming the lower layer of air which picks up water vapor from the lake, rises up through the colder air above, freezes and is deposited on the leeward (downwind) shores.

Blizzard of 77 January-February 1977 snowstorm in North America

The blizzard of 1977 hit Western New York as well as Southern Ontario from January 28 to February 1. Daily peak wind gusts ranging from 46 to 69 mph were recorded by the National Weather Service in Buffalo, with snowfall as high as 100 in (254 cm) recorded in areas, and the high winds blew this into drifts of 30 to 40 ft. There were 23 total storm-related deaths in western New York, with five more in northern New York.

Thundersnow

Thundersnow, also known as a winter thunderstorm or a thundersnowstorm, is an unusual kind of thunderstorm with snow falling as the primary precipitation instead of rain. It typically falls in regions of strong upward motion within the cold sector of an extratropical cyclone. Thermodynamically, it is not different from any other type of thunderstorm, but the top of the cumulonimbus cloud is usually quite low. In addition to snow, graupel or hail may fall.

A winter storm warning is a statement made by the National Weather Service of the United States which means a winter storm is occurring or is about to occur in the area, usually within 36 hours. Generally, a Winter Storm Warning is issued if the following criteria, at least, are forecast: usually between 4 inches (10 cm) to 7 inches (18 cm) or more of snow or usually 3 inches (7.6 cm) or more of snow with a large accumulation of ice. In the Southern United States, where severe winter weather is much less common and any snow is a more significant event, warning criteria are lower, as low as 1 inch (2.5 cm) in the southernmost areas: as one goes from north to south, the necessary accumulations lessen. A warning can also be issued during high impact events of lesser amounts, usually early or very late in the season when trees have leaves and damage can result. Winter Storm Warnings are issued when winds are less than 35mph; if the storm has winds above this wind speed, it becomes a blizzard warning.

This article describes severe weather terminology used by the National Weather Service (NWS) in the United States. The NWS, a government agency operating as an arm of the National Oceanic and Atmospheric Administration (NOAA) branch of the United States Department of Commerce (DoC), defines precise meanings for nearly all of its weather terms. This article describes NWS terminology and related weather scales used by the agency. Some terms may be specific to certain cities or regions.

Snowsquall Various forms of snowsqualls

A snowsquall is a sudden moderately heavy snow fall with blowing snow and strong, gusty surface winds. It is often referred to as a whiteout and is similar to a blizzard but is localized in time or in location and snow accumulations may or may not be significant.

Great Blizzard of 1978

The Great Blizzard of 1978 was a historic winter storm that struck the Ohio Valley and Great Lakes regions from Wednesday, January 25 through Friday, January 27, 1978. It has been cited as having been the worst blizzard in US history. The third lowest non-tropical atmospheric pressure ever recorded in the mainland United States occurred as the storm passed over Mount Clemens, Michigan, where the barometer fell to 956.0 mb (28.23 inHg) on January 26.

This article describes severe weather terminology used by the Meteorological Service of Canada, a branch within Environment and Climate Change Canada. The article primarily describes various weather warnings, and their criteria. Related weather scales and general weather terms are also addressed in this article. Some terms are specific to certain regions.

The term snowburst was coined in the 1960s by Prof. Robert Sykes who taught meteorology at SUNY Oswego, in northern New York. He used the term to describe a snowstorm that occurred December 7–11, 1958 in Oswego, New York. This particular storm dropped almost 6 feet of snow on the city including 40 inches in 24 hours. It was commonly referred to as "The Blizzard of '58" which was an inaccurate title, as the storm was not accompanied by high wind and the snow fell straight down. Another Blizzard of '58 occurred earlier that year in February across Oswego and Onondaga counties. This storm was an actual blizzard due to the high winds, blowing snow and cold. 26.1" of snow was measured at Syracuse N.Y. and drifts reached 20 feet in Oswego County.

Blowing snow is snow lifted from the surface by the wind, at a height of 8 feet or more, that will reduce visibility. Blowing snow can come from falling snow or snow that already accumulated on the ground but is picked up and blown about by strong winds. It is one of the classic requirements for a blizzard. Its METAR code is BLSN. If the snow remains below 8 feet, it will be called Drifting snow. The snow which is being blown about may deposit as snowdrifts.

Air-mass thunderstorm

An air-mass thunderstorm, also called an "ordinary", "single cell", or "garden variety" thunderstorm, is a thunderstorm that is generally weak and usually not severe. These storms form in environments where at least some amount of Convective Available Potential Energy (CAPE) is present, but very low levels of wind shear and helicity. The lifting source, which is a crucial factor in thunderstorm development, is usually the result of uneven heating of the surface, though they can be induced by weather fronts and other low-level boundaries associated with wind convergence. The energy needed for these storms to form comes in the form of insolation, or solar radiation. Air-mass thunderstorms do not move quickly, last no longer than an hour, and have the threats of lightning, as well as showery light, moderate, or heavy rainfall. Heavy rainfall can interfere with microwave transmissions within the atmosphere.

Atmospheric convection

Atmospheric convection is the result of a parcel-environment instability, or temperature difference layer in the atmosphere. Different lapse rates within dry and moist air masses lead to instability. Mixing of air during the day which expands the height of the planetary boundary layer leads to increased winds, cumulus cloud development, and decreased surface dew points. Moist convection leads to thunderstorm development, which is often responsible for severe weather throughout the world. Special threats from thunderstorms include hail, downbursts, and tornadoes.

A Blizzard Warning is an advisory issued by the National Weather Service of the United States which means sustained winds or frequent gusts of 35 mph / 15 m/s or greater with heavy snow is forecast for a period of 3 hours or more. A blizzard tends to reduce visibilities to 1/4 of a mile or less. A Severe Blizzard Warning is a variation issued in some cases of winds above 45 mph / 20 m/s and temperatures below 10 °F/-12 °C. Most local weather offices will activate and broadcast the SAME alarm tone on relevant NOAA Weather Radio stations for both varieties of warning. When the Wireless Emergency Alerts system went live in 2012, Blizzard Warnings were initially sent as alerts to mobile phones, however, this practice was discontinued in November 2013.

A Blizzard Watch was a bulletin issued by the National Weather Service of the United States which meant winds greater than 35 miles per hour, mixed with falling or blowing snow, and visibilities of 14 mile (0.4 km) or less is forecast for a period of 3 hours or more. A blizzard watch was issued 12 to 48 hours before an expected blizzard event. As the forecast solidifies, a blizzard watch would be either downgraded to a Winter Storm Warning or Winter Weather Advisory for blowing snow or upgraded to a Blizzard Warning.

Classifications of snow

Classifications of snow describe and categorize the attributes of snow-generating weather events, including the individual crystals both in the air and on the ground, and the deposited snow pack as it changes over time. Snow can be classified by describing the weather event that is producing it, the shape of its ice crystals or flakes, how it collects on the ground, and thereafter how it changes form and composition. Depending on the status of the snow in the air or on the ground, a different classification applies.

The December 2009 Midwest blizzard was a powerful extratropical cyclone which was of a category which meteorologists refer to as a cyclogenic bomb, a system which shows a drop in central pressure similar to the Rapid Intensification Cycle of a tropical cyclone, more than 1 mbar per hour for 12 to 24 hours or more. A sustained drop averaging more than 2.5 mbar/hr is termed explosive deepening/intensification, and this was the case with this rapidly deepening and intensifying storm as it traversed the Midwest and Ontario and on to Québec, Greenland and vicinity. In many locations wind, snowfall, and precipitation moisture content records dating back to the December 2, 1990 storm, the 1976-1978 period, the 1949 blizzard, or even further back were broken, with barometric pressure records falling as well. Both the central pressure (depth) and rate of change and differential over a given distance (intensity) were remarkable, and both caused hurricane-force winds in places.

December 2010 North American blizzard

The December 2010 North American blizzard was a major nor'easter and historic blizzard affecting the Contiguous United States and portions of Canada from December 5–29, 2010. From January 4–15, the system was known as Windstorm Benjamin in Europe. It was the first significant winter storm of the 2010–11 North American winter storm season and the fifth North American blizzard of 2010. The storm system affected the northeast megalopolis, which includes major cities such as Norfolk, Philadelphia, Newark, New York City, Hartford, Providence, and Boston. The storm brought between 12 and 32 inches of snow in many of these areas.

Glossary of meteorology Wikimedia list article

This glossary of meteorology is a list of terms and concepts relevant to meteorology and the atmospheric sciences, their sub-disciplines, and related fields.

References

  1. Ahrens, C. Donald. Essentials of Meteorology: An Invitation to the Atmosphere. C. Donald Ahrens. 7th ed. Stamford: Cengage Learning, 2015. 144. Print.
  2. 1 2 Rauber, Robert M; Walsh, John E; Charlevoix, Donna Jean (2012). Severe & Hazardous Weather. p. 265. ISBN   9780757597725.
  3. "National Weather Service Glossary" . Retrieved 27 January 2018.
  4. "Criteria for Public Weather Alerts". Government of Canada. Retrieved 27 January 2018.