HOME

TheInfoList



OR:

An Alberta clipper, also known as an Alberta low, Alberta cyclone, Alberta lee cyclone, Canadian clipper, or simply clipper, is a fast-moving
low-pressure system In meteorology, a low-pressure area, low area or low is a region where the atmospheric pressure is lower than that of surrounding locations. Low-pressure areas are commonly associated with inclement weather (such as cloudy, windy, with possible ...
that originates in or near the
Canadian province Within the geographical areas of Canada, the ten provinces and three territories are sub-national administrative divisions under the jurisdiction of the Canadian Constitution. In the 1867 Canadian Confederation, three provinces of British North ...
of
Alberta Alberta ( ) is one of the thirteen provinces and territories of Canada. It is part of Western Canada and is one of the three prairie provinces. Alberta is bordered by British Columbia to the west, Saskatchewan to the east, the Northwest Ter ...
just east of the
Rocky Mountains The Rocky Mountains, also known as the Rockies, are a major mountain range and the largest mountain system in North America. The Rocky Mountains stretch in straight-line distance from the northernmost part of western Canada, to New Mexico in ...
and tracks east-southeastward across southern Canada and the northern
United States The United States of America (U.S.A. or USA), commonly known as the United States (U.S. or US) or America, is a country primarily located in North America. It consists of 50 states, a federal district, five major unincorporated territorie ...
to the
North Atlantic Ocean The Atlantic Ocean is the second-largest of the world's five oceans, with an area of about . It covers approximately 20% of Earth's surface and about 29% of its water surface area. It is known to separate the "Old World" of Africa, Europe an ...
. Alberta clippers constitute a major winter-season
storm track ''Storm Track'' was the first magazine for and about storm chasing. The magazine was in circulation between 1977 and 2002. History and profile ''Storm Track'' was started in 1977 by chasing pioneer David Hoadley following an informal meeting o ...
for
extratropical cyclones Extratropical cyclones, sometimes called mid-latitude cyclones or wave cyclones, are low-pressure areas which, along with the anticyclones of high-pressure areas, drive the weather over much of the Earth. Extratropical cyclones are capable of p ...
in the
Northern Hemisphere The Northern Hemisphere is the half of Earth that is north of the Equator. For other planets in the Solar System, north is defined as being in the same celestial hemisphere relative to the invariable plane of the solar system as Earth's Nort ...
, tracking across the continent in 2–3 days while affecting weather in parts of the
Prairies Prairies are ecosystems considered part of the temperate grasslands, savannas, and shrublands biome by ecologists, based on similar temperate climates, moderate rainfall, and a composition of grasses, herbs, and shrubs, rather than trees, as the ...
and
central provinces The Central Provinces was a province of British India. It comprised British conquests from the Mughals and Marathas in central India, and covered parts of present-day Madhya Pradesh, Chhattisgarh and Maharashtra states. Its capital was Nagpur. ...
of
Canada Canada is a country in North America. Its ten provinces and three territories extend from the Atlantic Ocean to the Pacific Ocean and northward into the Arctic Ocean, covering over , making it the world's second-largest country by tot ...
, as well as the
Upper Midwest The Upper Midwest is a region in the northern portion of the U.S. Census Bureau's Midwestern United States. It is largely a sub-region of the Midwest. Although the exact boundaries are not uniformly agreed-upon, the region is defined as referring ...
,
Great Lakes The Great Lakes, also called the Great Lakes of North America, are a series of large interconnected freshwater lakes in the mid-east region of North America that connect to the Atlantic Ocean via the Saint Lawrence River. There are five lakes ...
, and
New England New England is a region comprising six states in the Northeastern United States: Connecticut, Maine, Massachusetts, New Hampshire, Rhode Island, and Vermont. It is bordered by the state of New York to the west and by the Canadian provinces ...
portions of the United States. They are associated with cold, dry continental air masses and generate small-scale, short-lived weather events typically producing 8–15 cm (3-6 inches) of snow in a 3-6 hour period. However, they can precipitate sudden temperature drops and sharp winds leading to local
blizzard A blizzard is a severe snowstorm characterized by strong sustained winds and low visibility, lasting for a prolonged period of time—typically at least three or four hours. A ground blizzard is a weather condition where snow is not falling b ...
conditions, especially when interacting with moisture from the Great Lakes.


Etymology

Alberta clippers take their name from
Alberta Alberta ( ) is one of the thirteen provinces and territories of Canada. It is part of Western Canada and is one of the three prairie provinces. Alberta is bordered by British Columbia to the west, Saskatchewan to the east, the Northwest Ter ...
, the province from which they appear to descend, and from
clipper ship A clipper was a type of mid-19th-century Merchant ship, merchant Sailing ship, sailing vessel, designed for speed. Clippers were generally narrow for their length, small by later 19th century standards, could carry limited bulk freight, and had ...
s of the 19th century, one of the fastest ships of that time. The term was coined in the late 1960s by Rheinhart Harms, a meteorologist at the U.S.
National Weather Service The National Weather Service (NWS) is an Government agency, agency of the Federal government of the United States, United States federal government that is tasked with providing weather forecasts, warnings of hazardous weather, and other weathe ...
Office in
Milwaukee Milwaukee ( ), officially the City of Milwaukee, is both the most populous and most densely populated city in the U.S. state of Wisconsin and the county seat of Milwaukee County. With a population of 577,222 at the 2020 census, Milwaukee is ...
,
Wisconsin Wisconsin () is a state in the upper Midwestern United States. Wisconsin is the 25th-largest state by total area and the 20th-most populous. It is bordered by Minnesota to the west, Iowa to the southwest, Illinois to the south, Lake M ...
, who noted the rapid speed '' ow rapid?' of these snow-producing storms as they moved across
the Dakotas The Dakotas is a collective term for the U.S. states of North Dakota and South Dakota. It has been used historically to describe the Dakota Territory, and is still used for the collective heritage, culture, geography, fauna, sociology, econom ...
from Alberta towards the Great Lakes. Its
colloquial Colloquialism (), also called colloquial language, everyday language or general parlance, is the linguistic style used for casual (informal) communication. It is the most common functional style of speech, the idiom normally employed in conver ...
use spread among U.S. and Canadian weather forecasters in the early 1970s. It would enter the scientific literature around the 1990s. Storms beginning their southward treks from other Canadian provinces, far less common than clippers, are often still referred to as clippers, or by the fanciful names ''Saskatchewan screamer'', ''Manitoba mauler'' or ''Ontario scari-o''.


Formation

A clipper originates when warm, moist winds from the
Pacific Ocean The Pacific Ocean is the largest and deepest of Earth's five oceanic divisions. It extends from the Arctic Ocean in the north to the Southern Ocean (or, depending on definition, to Antarctica) in the south, and is bounded by the continen ...
come into contact with the mountains in the provinces of
British Columbia British Columbia (commonly abbreviated as BC) is the westernmost province of Canada, situated between the Pacific Ocean and the Rocky Mountains. It has a diverse geography, with rugged landscapes that include rocky coastlines, sandy beaches, ...
and then
Alberta Alberta ( ) is one of the thirteen provinces and territories of Canada. It is part of Western Canada and is one of the three prairie provinces. Alberta is bordered by British Columbia to the west, Saskatchewan to the east, the Northwest Ter ...
. The air travels down the
lee side Windward () and leeward () are terms used to describe the direction of the wind. Windward is ''upwind'' from the point of reference, i.e. towards the direction from which the wind is coming; leeward is ''downwind'' from the point of reference ...
of the mountains, often forming a chinook in Alberta, then develops into a storm over the Canadian prairies when it becomes entangled with the cold
air mass In meteorology, an air mass is a volume of air defined by its temperature and humidity. Air masses cover many hundreds or thousands of square miles, and adapt to the characteristics of the surface below them. They are classified according to la ...
that normally occupies that region in winter. The storm then moves east-southeast riding the
jet stream Jet streams are fast flowing, narrow, meandering thermal wind, air currents in the Atmosphere of Earth, atmospheres of some planets, including Earth. On Earth, the main jet streams are located near the altitude of the tropopause and are west ...
, and passes off the upper Atlantic Coast, normally north of
Delaware Bay Delaware Bay is the estuary outlet of the Delaware River on the northeast seaboard of the United States. It is approximately in area, the bay's freshwater mixes for many miles with the saltwater of the Atlantic Ocean. The bay is bordered inlan ...
. The chinook which in part originates the Alberta clipper usually brings relatively warm weather (often approaching 10 °C/50 °F in the depths of winter) to southern Alberta itself, and the term is therefore not used in Alberta.


Effects

The storms sweep in at high speed over whatever land they encounter, usually bringing with them sharp cold fronts and drastically lower temperatures. It is not uncommon for an Alberta clipper to cause temperatures to drop by 16 °C (30 °F) in as little as 10 to 12 hours. Often, the storms bring biting winds with them, only increasing the effect of the lower temperatures. Winds in advance of and during an Alberta clipper are frequently as high as 56 to 72 km/h (35 to 45 mph). These conditions would cause
wind chill Wind chill or windchill (popularly wind chill factor) is the lowering of body temperature due to the passing-flow of lower-temperature air. Wind chill numbers are always lower than the air temperature for values where the formula is valid. When ...
values to drop into the −30 to −45 Celsius (−20 to −50 Fahrenheit) range across the upper Midwest and Great Lakes. Snowfall amounts with these systems tend to be small (on the order of 1–3 inches or 2.5–7.5 cm), as the relative lack of moisture and quick movement inhibit substantial snowfall totals. However, several factors could combine to produce higher snow accumulations (6 inches/15 cm or more). These factors include access to more moisture (which raises precipitation amounts), slower system movement (which increases snowfall duration), and colder temperatures (which increases the snow to water ratio). The southern and eastern shores of the
Great Lakes The Great Lakes, also called the Great Lakes of North America, are a series of large interconnected freshwater lakes in the mid-east region of North America that connect to the Atlantic Ocean via the Saint Lawrence River. There are five lakes ...
often receive enhanced snowfall from Alberta clippers during the winter, due to lake enhancement. The
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. The lower layer of air, heated up by the lake water, picks up water vapor from the lake and rises up through ...
can add substantially to the overall snowfall total. Occasionally the clippers, when reaching the upper
Atlantic seaboard The East Coast of the United States, also known as the Eastern Seaboard, the Atlantic Coast, and the Atlantic Seaboard, is the coastline along which the Eastern United States meets the North Atlantic Ocean. The eastern seaboard contains the coa ...
(usually north of Delaware), " bomb out" and can cause severe winter weather along the coast from Boston northward as Atlantic moisture is tapped. Snowfall amounts can approach 6–12" or more when this happens. However, typically, Alberta clippers are not large snow producers south of Boston. During the winter, Alberta clippers can occur somewhat frequently, with system intervals on the order of two to four days common during active periods.


See also

*
Ground blizzard Ground blizzard refers to a weather condition where loose snow or ice on the ground is lifted and blown by strong winds. This can occur in the absence of precipitation, and can even occur when the sky is clear. This is in contrast to "ordinary" b ...
*
Panhandle hook A panhandle hook (also called a pan handle hook or Texas hooker) is a relatively infrequent winter storm system whose cyclogenesis occurs in the South to southwestern United States from the late fall through winter and into the early Spring (seaso ...
*
Polar vortex A circumpolar vortex, or simply polar vortex, is a large region of cold, rotating air that encircles both of Earth's polar regions. Polar vortices also exist on other rotating, low-obliquity planetary bodies. The term polar vortex can be used to ...
*
Snowsquall A snowsquall, or snow squall, is a sudden moderately heavy snowfall 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 accumulat ...
*
Windchill Wind chill or windchill (popularly wind chill factor) is the lowering of body temperature due to the passing-flow of lower-temperature air. Wind chill numbers are always lower than the air temperature for values where the formula is valid. When ...


References


Further reading

* Dunlop, Storm: ''The Weather Identification Handbook: The Ultimate Guide for Weather Watchers'', 2003, The Lyons Press, . * Williams, Jack: ''The Weather Book'', 1997, Vintage Books, .


External links


University of Illinois at Urbana-Champaign, Meteorology Department: ''Extratropical Lows: Clippers''
{{Extratropical cyclones Extratropical cyclones * * Natural history of Alberta Natural history of Saskatchewan