Editing Alberta clipper

{{Short description|Low pressure area weather system common to North America}}
{{Redirect|Alberta Clipper|the oil pipeline running from Alberta to Wisconsin|Alberta Clipper pipeline}}
[[Image:Clipper albertain.png|350px|thumb|right|Average trajectory of a clipper]]

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]] that originates in or near the [[Canadian province]] of [[Alberta]] just east of the [[Rocky Mountains]] and tracks east-southeastward across southern Canada and the northern [[United States]] to the [[North Atlantic Ocean]].<ref>{{cite web |url=https://glossary.ametsoc.org/wiki/Alberta_clipper |title=Alberta clipper |date= 26 January 2012|website= Glossary of Meteorology |publisher= American Meteorological Society  |access-date=2021-09-07 |quote= A low pressure system that is often fast-moving, has low moisture content, and originates in western Canada (in or near Alberta province). In the wintertime, it may be associated with a narrow but significant band of snowfall, and typically affects portions of the plains states, Midwest, and East Coast.}}</ref><ref>{{cite web |url=https://www.merriam-webster.com/dictionary/Alberta%20Clipper |title=Alberta Clipper |work=Merriam-Webster.com Dictionary |publisher=Merriam-Webster |access-date=2021-09-07 |quote=a fast-moving low-pressure weather system that develops east of the Rocky Mountains in western Canada during winter months and moves to the east-southeast across central Canada and into the northern U.S.}}</ref><ref name="cdnency">{{cite encyclopedia |last=Serralheiro-O'Neill |first=Benjamin |date=2021-06-17 |title=Alberta Clipper |url=https://www.thecanadianencyclopedia.ca/en/article/alberta-clipper |encyclopedia=[[The Canadian Encyclopedia]] |publisher=Historica Canada |access-date=2021-09-07 |quote=An Alberta Clipper is a type of low-pressure weather system that forms in Alberta or nearby, on the eastern side of the Rocky Mountains.}}</ref>

Alberta clippers constitute a major winter-season  [[storm track]]  for  [[extratropical cyclones]] in the [[Northern Hemisphere]], tracking across the continent in 2–3 days while affecting weather in parts of the [[Prairie Provinces|Prairies]] and [[Provinces and territories of Canada|central provinces]] of [[Canada]], as well as the [[Upper Midwest]], [[Great Lakes region (North America)|Great Lakes]], and [[New England]] portions of the United States. They are associated with cold, dry continental [[air masses]] and generate small-scale, short-lived weather events typically producing {{convert|8|–|15|cm|in|abbr=on}} of snow in a three to six hour period. However, they can precipitate sudden temperature drops and sharp winds leading to local [[blizzard]] conditions, especially when interacting with moisture from the Great Lakes.<ref name="Thomas">{{cite journal |last1= Thomas |first1= Blaine C.|last2= Martin |first2= Jonathan E. |date= 2007-04-01 |title= A Synoptic Climatology and Composite Analysis of the Alberta Clipper |journal= Weather and Forecasting  |volume= 22 |issue=2 |pages=315–333  |doi= 10.1175/WAF982.1|bibcode= 2007WtFor..22..315T|s2cid= 59456654|doi-access= free}}</ref><ref name="Thurlow">{{Cite web |url=http://www.weathernotebook.org/transcripts/2000/02/15.html |title=Alberta Clipper |publisher=The Weather Notebook |access-date=2007-04-16 |first=Dave |last=Thurlow |archive-url=https://web.archive.org/web/20070318133657/http://www.weathernotebook.org/transcripts/2000/02/15.html |archive-date=18 March 2007 |url-status=dead}}</ref>

== Etymology ==
[[File:Clipper barque Spirit of the Age, PY0633.jpg|thumb|Clipper barque ''Spirit of the Age'' 1854 by [[Thomas Goldsworthy Dutton|T. G. Dutton]]]]

Alberta clippers take their name from [[Alberta]], the province from which they appear to descend, and from [[clipper ship]]s of the 19th century, one of the fastest ships of that time.<ref name="cdnency"/><ref name=douglas>{{cite book |last=Douglas |first=Paul |title=Restless Skies |url=https://books.google.com/books?id=CzMfTLESpcUC&pg=PA50 |publisher=Barnes & Noble Publishing |year=2004 |isbn=0-7607-6113-2 |page=50}}</ref>

The term was coined in the late 1960s by Rheinhart Harms, a meteorologist at the U.S. [[National Weather Service]] Office in [[Milwaukee]], [[Wisconsin]], who noted the rapid speed of these snow-producing storms as they moved across [[the Dakotas]] from Alberta towards the Great Lakes.<ref>{{cite journal |last1= Harms |first1= Rheinhart |date= November 1970 |title= Snow Forecasting for Southeasern Wisconsin |url=https://www.tandfonline.com/doi/abs/10.1080/00431672.1973.9931668|journal=NOAA Technical Memorandum |volume= 26 |issue= NWSTM CR 38 |pages= 250–271 |doi= 10.1080/00431672.1973.9931668|access-date=2021-09-07|url-access= subscription }}</ref><ref>{{cite journal |last1= Harms|first1= Rheinhart  | date= December 1973 |title= Snow Forecasting for Southeastern Wisconsin |url= https://www.tandfonline.com/doi/abs/10.1080/00431672.1973.9931668 |journal= Weatherwise  |volume= 26 |issue=6 |pages=250–271 |doi=10.1080/00431672.1973.9931668 |access-date=2021-09-07|url-access= subscription }}</ref>  Its [[colloquial]] use spread among U.S. and Canadian weather forecasters in the early 1970s.<ref>{{cite news |last=Skilling |first= Tom|date= October 17, 2014 |title= What's the origin of 'Alberta clipper'? |url=https://www.chicagotribune.com/weather/ct-wea-1018-asktom-20141017-column.html |work= Chicago Tribune |location= |access-date=2021-09-07}}</ref> It entered 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''.<ref name = "cdnency" /><ref>{{cite web|last=Swanson |first=Bob |title=Snowstorms or wrestling names? |work=[[USA Today]] |date=December 5, 2007 |url=http://blogs.usatoday.com/weather/2007/12/snowstorms-or-w.html |access-date=2008-05-07 |url-status=dead |archive-url=https://web.archive.org/web/20080804121446/http://blogs.usatoday.com/weather/2007/12/snowstorms-or-w.html |archive-date=August 4, 2008 }}</ref><ref>{{cite web |title=Glossary: Alberta Clipper |publisher=[[NOAA]] |url=http://www.crh.noaa.gov/glossary.php?word=Alberta%20clipper |access-date=2007-05-10 }}</ref><ref>{{cite web |first=John D. |last=Gordon |title=A Comprehensive Winter Weather Forecast Checklist |publisher=[[National Weather Service]] |location=[[Springfield, Missouri]] |url=http://www.weather.gov/sgf/winter_checklist_paper |access-date=2016-01-25 }}</ref>

==Formation==
[[Image:MN weatherpatterns.svg|thumb|right|Typical winter storm tracks in Minnesota.]]

A clipper originates when warm, moist winds from the [[Pacific Ocean]] come into contact with the mountains in the provinces of [[British Columbia]] and then [[Alberta]].<ref name="Thurlow"/> The air travels down the [[lee side]] of the mountains, often forming a [[chinook wind|chinook]] in Alberta, then develops into a storm over the Canadian prairies when it becomes entangled with the cold [[air mass]] that normally occupies that region in winter. The storm then moves east-southeast riding the [[jet stream]], and passes off the upper Atlantic Coast, normally north of [[Delaware Bay]].

The chinook, which in part originates the Alberta clipper, usually brings relatively warm weather (often approaching {{cvt|10|C}} 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 {{cvt|16|C-change|0}} in as little as 10 to 12&nbsp;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 {{cvt|56|to|72|km/h}}. These conditions would cause [[wind chill]] values to drop into the {{cvt|-30|to|-45|C|0}} range across the upper Midwest and Great Lakes.<ref name="Islandnet">{{Cite web
|url=http://islandnet.com/~see/weather/storm/neaster.htm
|title=Nor'easters and Alberta Clippers
|publisher=The Weather Doctor
|access-date=2016-04-10
|first=Keith
|last=Heidorn
|archive-url=https://web.archive.org/web/20070416200448/http://www.islandnet.com/~see/weather/storm/neaster.htm
|archive-date=16 April 2007
|url-status=dead
}}</ref>

Snowfall amounts with these systems tend to be small (on the order of {{cvt|2.5|-|7|cm|disp=sqbr}}), as the relative lack of moisture and quick movement inhibit substantial snowfall totals. However, several factors could combine to produce higher snow accumulations ({{cvt|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]] often receive enhanced snowfall from Alberta clippers during the winter, due to lake enhancement. The [[lake-effect snow]] can add substantially to the overall snowfall total.<ref name="Islandnet"/>

Occasionally the clippers, when reaching the upper [[East Coast of the United States|Atlantic seaboard]] (usually north of Delaware), "[[bomb (meteorology)|bomb out]]" and can cause severe winter weather along the coast from Boston northward as Atlantic moisture is tapped. Snowfall amounts can approach {{cvt|6|–|12|in|order=flip}} 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]]
* [[Panhandle hook]]
* [[Polar vortex]]
* [[Snow squall]]
* [[Wind chill]]

==References==
{{Reflist}}

==Further reading==
* {{Cite book |last=Dunlop |first=Storm |date=2003 |title=The Weather Identification Handbook: The Ultimate Guide for Weather Watchers |location=Guilford, Conn. |publisher=The Lyons Press |isbn=9781585748570 |oclc=52307033}}
* {{Cite book |last=Williams |first=Jack |date=1997 |title=The Weather Book |url=https://books.google.com/books?id=PfOKDQAAQBAJ |edition=2nd rev. and updated |location=New York |publisher=Vintage Books |isbn=0-679-77665-6 |oclc=37820330}}

==External links==
* [https://web.archive.org/web/20061230050400/http://severewx.atmos.uiuc.edu/index.09.clippers.html Extratropical Lows: Clippers]—University of Illinois at Urbana-Champaign, Meteorology Department

{{Cyclones}}

[[Category:Blizzards in Canada|*]]
[[Category:Blizzards in the United States|*]]
[[Category:Extratropical cyclones]]
[[Category:Natural history of Alberta]]
[[Category:Natural history of Saskatchewan]]