Chinook winds, or simply Chinooks, are two types of prevailing warm, generally westerly winds in western North America: Coastal Chinooks and interior Chinooks. The coastal Chinooks are persistent seasonal, wet, southwesterly winds blowing in from the ocean. The interior Chinooks are occasional warm, dry föhn winds blowing down the eastern sides of interior mountain ranges. The coastal Chinooks were the original term, used along the northwest coast, and the term in the interior of North America is later and derives from the coastal term. * Along the

Pacific Northwest The Pacific Northwest (sometimes Cascadia, or simply abbreviated as PNW) is a geographic region in western North America bounded by its coastal waters of the Pacific Ocean to the west and, loosely, by the Rocky Mountains to the east. Tho ...

coast, where the name is pronounced ('chin'+'uk'), the name refers to wet, warm winds off the ocean from the southwest; this is the original use of the term. The coastal Chinook winds deliver tremendous amounts of moisture both as rain along the coast and snow in the coastal mountains, that sustain the characteristic

temperate rainforests Temperate rainforests are coniferous or broadleaf forests that occur in the temperate zone and receive heavy rain. Temperate rain forests occur in oceanic moist regions around the world: the Pacific temperate rain forests of North American Pac ...

and climate of the

* In North American western interior, the same name is used for föhn winds, generally, where the

Canadian Prairies The Canadian Prairies (usually referred to as simply the Prairies in Canada) is a region in Western Canada. It includes the Canadian portion of the Great Plains and the Prairie Provinces, namely Alberta, Saskatchewan, and Manitoba. These provin ...

and Great Plains lie immediately east of various interior mountain ranges. There the name is pronounced ('shin'+'uk'). The same warm, wet coastal winds can also become the warm föhn winds on the eastern sides of mountain ranges, after having lost their moisture on the western sides; however, due to expanded use of the term in the interior for any föhn wind, interior Chinooks are not necessarily originally coastal Chinooks. In the interior of North America, the

Blackfoot people The Blackfoot Confederacy, ''Niitsitapi'' or ''Siksikaitsitapi'' (ᖹᐟᒧᐧᒣᑯ, meaning "the people" or " Blackfoot-speaking real people"), is a historic collective name for linguistically related groups that make up the Blackfoot or Bla ...

call these winds the "snow eater"; however, the more commonly used term "Chinook" originates from the name of the eponymous

Chinook people Chinookan peoples include several groups of Indigenous people of the Pacific Northwest in the United States who speak the Chinookan languages. Since at least 4000 BCE Chinookan peoples have resided along the Lower and Middle Columbia River (W ...

, who lived near the ocean, along the lower Columbia River, where the term was first derived. The reference to "a Chinook" wind or weather system originally meant, to euro-American settlers along the Pacific Northwest coast, a warming wind from the ocean blowing into the interior regions of the

of the North America. A strong föhn wind can make snow one foot (30 cm) deep almost vanish in one day. The snow partly sublimates and partly melts and evaporates in the dry wind. Chinook winds have been observed to raise winter

temperature Temperature is a physical quantity that expresses quantitatively the perceptions of hotness and coldness. Temperature is measurement, measured with a thermometer. Thermometers are calibrated in various Conversion of units of temperature, temp ...

, often from below −20 °C (−4°F) to as high as 10–20°C (50–68°F) for a few hours or days, then temperatures plummet to their base levels.

In the Pacific Northwest

"Chinook" is used for coastal Chinook winds in

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 is the original use of the term, being rooted in the lore of coastal natives and immigrants, and brought to

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 ...

by French-speaking fur-traders. Such winds are extremely wet and warm and arrive off the western coast of North America from the southwest. These same winds have more recently been called the

pineapple express Pineapple Express is a non-technical term for a meteorological phenomenon characterized by a strong and persistent large-scale flow of warm moist air, and the associated heavy precipitation both in the waters immediately northeast of the Hawaii ...

, since they are of tropical origin, roughly from the area of the

Pacific 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 contine ...

near Hawaii. The air associated with a coastal Chinook is stable; this minimizes wind gusts and often keeps winds light in sheltered areas. In exposed areas, fresh

gale A gale is a strong wind; the word is typically used as a descriptor in nautical contexts. The U.S. National Weather Service defines a gale as sustained surface winds moving at a speed of between 34 and 47 knots (, or ).powder snow, sometimes to

sea level Mean sea level (MSL, often shortened to sea level) is an average surface level of one or more among Earth's coastal bodies of water from which heights such as elevation may be measured. The global MSL is a type of vertical datuma standardise ...

. Snowfalls and the cold spells that spawned them only last a few days during a Chinook; as the warm coastal Chinooks blow from the southwest, they push back east the cold Arctic air. The snow melts quickly and is gone within a week. The effects on the

Interior of British Columbia , settlement_type = Region of British Columbia , image_skyline = , nickname = "The Interior" , subdivision_type = Country , subdivision_name = , subdivision_type1 = Province , subd ...

when a coastal Chinook is in effect are the reverse. In a rainy spell, most of the heavy moisture will be wrung out of the rising air as a consequence of crossing over the mountain ramparts before the air mass descends (and hence warms and dries) into the

Fraser Canyon The Fraser Canyon is a major landform of the Fraser River where it descends rapidly through narrow rock gorges in the Coast Mountains en route from the Interior Plateau of British Columbia to the Fraser Valley. Colloquially, the term "Fraser ...

and the

Thompson River The Thompson River is the largest tributary of the Fraser River, flowing through the south-central portion of British Columbia, Canada. The Thompson River has two main branches, the South Thompson River and the North Thompson River. The ri ...

Okanagan The Okanagan ( ), also known as the Okanagan Valley and sometimes as the Okanagan Country, is a region in the Canadian province of British Columbia defined by the basin of Okanagan Lake and the Canadian portion of the Okanagan River. It is par ...

area. The effects are similar to those of an Albertan interior Chinook, though not to the same extreme, partly because the Okanagan is relatively warmer than

the Prairies The Canadian Prairies (usually referred to as simply the Prairies in Canada) is a region in Western Canada. It includes the Canadian portion of the Great Plains and the Prairie Provinces, namely Alberta, Saskatchewan, and Manitoba. These provin ...

, and partly because of the additional number of precipitation-catching mountain ranges between Kelowna and Calgary. When the coastal Chinook brings snow to the coast during a period of coastal cold, bright but chilly weather in the interior will give way to a slushy melting of snow, more due to the warm spell than because of rain.

Pronunciation in the Pacific Northwest

The word "Chinook" remains in common use among local fishermen and people in communities along the British Columbia Coast, and coastal Washington and

Oregon Oregon () is a state in the Pacific Northwest region of the Western United States. The Columbia River delineates much of Oregon's northern boundary with Washington, while the Snake River delineates much of its eastern boundary with Idaho. T ...

, and in particular, the term is used in the

Puget Sound Puget Sound ( ) is a sound of the Pacific Northwest, an inlet of the Pacific Ocean, and part of the Salish Sea. It is located along the northwestern coast of the U.S. state of Washington. It is a complex estuarine system of interconnected ma ...

area of Washington. Coastal "Chinook" is not pronounced ''shin-uk'' () as it is in the interior, east of the Cascades, but is in the original coastal pronunciation ''chin-uk'' (). In

and other parts of the

, the word Chinook was predominantly pronounced . However, the common pronunciation current throughout most of the inland

, Alberta, and the rest of Canada, is , as in French. This difference may be because it was the Métis employees of the

Hudson's Bay Company The Hudson's Bay Company (HBC; french: Compagnie de la Baie d'Hudson) is a Canadian retail business group. A fur trading business for much of its existence, HBC now owns and operates retail stores in Canada. The company's namesake business di ...

, who were familiar with the Chinook people and country, brought the name east of the Cascades and

Rockies 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 ...

, along with their own ethnified pronunciation. Early records are clear that ''tshinook'' was the original pronunciation, before the word's transmission east of the Rockies.

First nations myth from British Columbia

Native legend of the

Lil'wat The Lil'wat First Nation ( lil, líl̓watǝmx), a.k.a. the Lil'wat Nation or the Mount Currie Indian Band, is a First Nation band government located in the southern Coast Mountains region of the Interior of the Canadian province of British Co ...

subgroup of the St'at'imc tells of a girl named Chinook-Wind, who married Chinook Glacier, and moved to his country, which was in the area of today's

Birkenhead River The Birkenhead River, formerly known as the Portage River, the Pole River and the Mosquito River, is a major tributary of the Lillooet River, which via Harrison Lake and the Harrison River is one of the major tributaries of the lower Fraser River. ...

. She pined for her warm sea-home in the southwest, and sent a message to her people. They came to her in a vision in the form of snowflakes, and told her they were coming to get her. They came in great number and quarrelled with Glacier over her, but they overwhelmed him and in the end she went home with them. While on the one hand this tale tells a tribal family-relations story, and family/tribal history as well, it also seems to be a parable of a typical weather pattern of a southwesterly wind at first bringing snow, then rain, and also of the melting of a glacier, namely the Place Glacier near Gates Lake at Birken. Thus, it also tells of a migration of people to the area – or a war, depending on how the details of the legend might be read, with Chinook-wind taking the part of Helen in a

First Nations First Nations or first peoples may refer to: * Indigenous peoples, for ethnic groups who are the earliest known inhabitants of an area. Indigenous groups *First Nations is commonly used to describe some Indigenous groups including: **First Natio ...

analogue to the

Trojan War In Greek mythology, the Trojan War was waged against the city of Troy by the Achaeans (Greeks) after Paris of Troy took Helen from her husband Menelaus, king of Sparta. The war is one of the most important events in Greek mythology and ...

Chinooks in Alberta and eastern British Columbia

Interior Chinooks are most prevalent over southern

in Canada, especially in a belt from Pincher Creek and

Crowsnest Pass Crowsnest Pass (sometimes referred to as Crow's Nest Pass, french: link=no, col du Nid-de-Corbeau) is a low mountain pass across the Continental Divide of the Canadian Rockies on the Alberta– British Columbia border. Geography The pass is ...

through Lethbridge, which get 30–35 Chinook days per year, on average. Interior Chinooks become less frequent further south in the United States, and are not as common north of

Red Deer The red deer (''Cervus elaphus'') is one of the largest deer species. A male red deer is called a stag or hart, and a female is called a hind. The red deer inhabits most of Europe, the Caucasus Mountains region, Anatolia, Iran, and parts of we ...

, but they can and do occur annually as far north as High Level in northwestern Alberta and Fort St. John in northeastern

, and as far south as Las Vegas, Nevada, and occasionally to Carlsbad, in eastern New Mexico. In southwestern Alberta, interior Chinook winds can gust in excess of hurricane force . On 19 November 1962, an especially powerful Chinook in Lethbridge gusted to . In Pincher Creek, the temperature rose by , from , in one hour on 6 January 1966. Trains have been known to be derailed by interior Chinook winds. During the winter, driving can be treacherous, as the wind blows snow across roadways, sometimes causing roads to vanish and snowdrifts to pile up higher than a metre. Empty semitrailer trucks driving along Highway 3 and other routes in southern Alberta have been blown over by the high gusts of wind caused by interior Chinooks. Calgary, Alberta also gets many interior Chinooks – the

Bow Valley Bow Valley is a valley located along the upper Bow River in Alberta, Canada. The name "Bow" refers to the reeds that grew along its banks and which were used by the local First Nations people to make bows; the Blackfoot language name for th ...

in the Canadian Rockies west of the city acts as a natural wind tunnel, funneling the chinook winds. On 27 February 1992,

Claresholm Claresholm is a town located within southern Alberta, Canada. It is located on Highway 2, approximately northwest of the City of Lethbridge and south of the City of Calgary. One of the Famous Five involved in the Persons Case, Louise McKinne ...

, Alberta, a small city just south of Calgary, recorded a temperature of ; again, the next day was recorded. These are some of Canada's highest February temperatures.

Clashing with Arctic air mass

The interior Chinooks can seem to battle with Arctic air masses at times. This clash of temperatures can remain stationary, or move back and forth, in the latter case causing such fluctuations as a warm morning, a bitterly cold afternoon, and a warm evening. A curtain of fog often accompanies the clash between warm to the west and cold to the east.

Chinook arch

Two common cloud patterns seen in the interior during this time are a chinook arch overhead, and a bank of clouds (also referred to as a cloud wall) obscuring the mountains to the west. The bank appears to be an approaching storm, but does not advance any further to the east. One of its most striking features of the interior Chinook weather system is the ''Chinook arch'', a föhn cloud in the form of a band of stationary stratus clouds, caused by air rippling over the mountains due to orographic lifting. To those unfamiliar with it, the Chinook arch may at times look like a threatening storm cloud, however, the arch clouds rarely produce rain or snow. They can also create stunning sunrises and sunsets. A similar phenomenon, the

Nor'west arch The Nor'west arch is a weather pattern peculiar to the east coast of New Zealand's South Island. For this reason, it is also often referred to as the Canterbury arch, although it is visible in both Otago and Marlborough as well as in the Canterbur ...

, also a föhn cloud, is seen in southern

New Zealand New Zealand ( mi, Aotearoa ) is an island country in the southwestern Pacific Ocean. It consists of two main landmasses—the North Island () and the South Island ()—and over 700 smaller islands. It is the sixth-largest island count ...

. The stunning colors seen in the Chinook arch are quite common. Typically, the colours will change throughout the day, starting with yellow, orange, red, and pink shades in the morning as the sun comes up, grey shades at midday changing to pink / red colours, and then orange / yellow hues just before the sun sets. Image:Chinook-arch.JPG, Chinook arch over Calgary, 6 January 2003 Image:chinook-arch-01.jpg, The extreme colors of a Chinook arch File:Chinook19.11.05.jpg, Chinook arch in Calgary, Alberta, 19 November 2005 Image:Chinook Arch-Calgary.JPG, Chinook arch over Calgary, March 2007 Image:Okanagan-Arch.jpg, Chinook arch over Kelowna, BC, Canada, 2 October 2007

Cause of occurrence

The interior Chinook is a föhn wind, a rain shadow wind which results from the subsequent adiabatic warming of air which has dropped most of its moisture on windward slopes (

orographic lift Orographic lift occurs when an air mass is forced from a low elevation to a higher elevation as it moves over rising terrain. As the air mass gains altitude it quickly cools down adiabatically, which can raise the relative humidity to 100% and cr ...

). As a consequence of the different adiabatic rates of moist and dry air, the air on the leeward slopes becomes warmer than equivalent elevations on the windward slopes. Sometimes the interior Chinooks are caused by the same air flow as the coastal Chinooks: As moist winds from the Pacific (coastal Chinooks) are forced to rise over the mountains, the moisture in the air is condensed and falls out as precipitation, while the air cools at the moist adiabatic rate of The dried air then descends on the leeward side of the mountains, warming at the dry adiabatic rate of The turbulence of the high winds also can prevent the usual nocturnal

temperature inversion In meteorology, an inversion is a deviation from the normal change of an atmospheric property with altitude. It almost always refers to an inversion of the air temperature lapse rate, in which case it is called a temperature inversion. Nor ...

from forming on the lee side of the slope, allowing night-time temperatures to remain elevated. Quite often, when the

coast is being drenched by rain, the windward (western) side of the

is being hammered by snow (robbing the air of its moisture), and the leeward (eastern) side of the Rockies in Alberta is basking in a föhn Chinook. The three different weather conditions are all caused by the same flow of air, hence the confusion over the use of the name "Chinook wind".

Interior Chinooks and gardening on Great Plains

The frequent midwinter thaws by interior Chinooks in Great Plains country are more of a bane than a blessing to gardeners. Plants can be visibly brought out of dormancy by persistent, warm interior Chinook winds, or have their hardiness reduced even if they appear to remain dormant. In either case, they become vulnerable to later cold waves. Many plants which do well at

Winnipeg Winnipeg () is the capital and largest city of the province of Manitoba in Canada. It is centred on the confluence of the Red and Assiniboine rivers, near the longitudinal centre of North America. , Winnipeg had a city population of 749, ...

– where constant cold maintains dormancy throughout the winter – are difficult to grow in the Alberta Chinook belt. Examples include basswood, some

apple An apple is an edible fruit produced by an apple tree (''Malus domestica''). Apple trees are cultivated worldwide and are the most widely grown species in the genus ''Malus''. The tree originated in Central Asia, where its wild ancestor, ' ...

, raspberry, and juneberry varieties, and Amur maples. Native trees in the interior Chinook-affected areas of Alberta are known to be small, with much less growth than the same species growing in areas not affected by interior Chinook winds. This is once again caused by the "off-and-on" dormancy throughout winter.

Health

Interior Chinook winds are said to sometimes cause a sharp increase in the number of migraine headaches suffered by the locals. At least one study conducted by the department of clinical neurosciences at the

University of Calgary The University of Calgary (U of C or UCalgary) is a public research university located in Calgary, Alberta, Canada. The University of Calgary started in 1944 as the Calgary branch of the University of Alberta, founded in 1908, prior to being ins ...

supports that belief. They are popularly believed to increase

irritability Irritability (also called as crankiness) is the excitatory ability that living organisms have to respond to changes in their environment. The term is used for both the physiological reaction to stimuli and for the pathological, abnormal or excessi ...

and sleeplessness. In mid-winter over major centres such as Calgary, interior Chinooks can often override cold air in the city,

trapping Animal trapping, or simply trapping or gin, is the use of a device to remotely catch an animal. Animals may be trapped for a variety of purposes, including food, the fur trade, hunting, pest control, and wildlife management. History Neolithi ...

the

pollutants A pollutant or novel entity is a substance or energy introduced into the environment that has undesired effects, or adversely affects the usefulness of a resource. These can be both naturally forming (i.e. minerals or extracted compounds like o ...

in the cold air and causing inversion smog. At such times, it is possible for it to be cold at street level and much warmer at the tops of the skyscrapers and in higher terrain. In 1983, on the 45th floor bout 145 m (460 ft) above the streetof the Petro-Canada Center, carpenters worked shirtless in +12 °C, windy conditions (temperature reported to them by overhead crane operator), but were chagrined to find out the street temperature was still −20 °C as they left work at 3:30 that afternoon.

Chinooks and föhn winds in the inland United States

In the North American western interior, winds that are generally called föhn winds by

meteorologist A meteorologist is a scientist who studies and works in the field of meteorology aiming to understand or predict Earth's atmospheric phenomena including the weather. Those who study meteorological phenomena are meteorologists in research, while t ...

s and

climatologist Climatology (from Greek , ''klima'', "place, zone"; and , ''-logia'') or climate science is the scientific study of Earth's climate, typically defined as weather conditions averaged over a period of at least 30 years. This modern field of study ...

s are called 'Chinooks'. Regardless of the name, föhns can occur on the leeward side of any nearby mountain range. The föhns called 'Chinook winds' are seen throughout most of inland western North America, particularly the Rocky Mountain region.

Montana Montana () is a state in the Mountain West division of the Western United States. It is bordered by Idaho to the west, North Dakota and South Dakota to the east, Wyoming to the south, and the Canadian provinces of Alberta, British Columb ...

especially has a significant amount of föhn winds throughout much of the state during the winter months, but particularly coming off the

Rocky Mountain Front The Rocky Mountain Front is a somewhat unified geologic and ecosystem area in North America where the eastern slopes of the Rocky Mountains meet the plains. In 1983, the Bureau of Land Management called the Rocky Mountain Front "a nationally signif ...

in the northern and west-central areas of the state. On rare occasions, Chinook winds generated on the eastern slope of the Rocky Mountains have reached as far east as Wisconsin.

Records

Loma, Montana has the world record for the most extreme temperature change in a 24-hour period. On January 15, 1972, the temperature increased from −54 °F to 49 °F (−48 °C to 9 °C), a 103 °F (58 °C) change in temperature.

Spearfish, South Dakota Spearfish ( Lakota: ''Hočhápȟe'') is a city in Lawrence County, South Dakota. The population was 12,193 at the time of the 2020 census. History Before the Black Hills Gold Rush of 1876, the area was used by Native Americans (primarily bands ...

holds the world record for the fastest increase in temperature. On January 22, 1943, the temperature increased from −4 °F to 45 °F (−20 °C to 7 °C), a 49 °F (27 °C) change in temperature. This occurred in just 2 minutes.Parker, Watson (1981). – ''Deadwood: The Golden Years''. – Lincoln, Nebraska: The University of Nebraska. – p.158. – .

Rapid City, South Dakota Rapid City ( lkt, link=no, Mni Lúzahaŋ Otȟúŋwahe; "Swift Water City") is the second most populous city in South Dakota and the county seat of Pennington County. Named after Rapid Creek, where the settlement developed, it is in western So ...

holds the world record for the fastest decrease in temperature. On January 10, 1911, the temperature decreased from 60 °F to 13 °F (16 °C to −11 °C), a 47 °F (26.1 °C) change in temperature.

Squamish winds, williwaws, and Chugach föhns

The resulting outflow wind is more or less the opposite of

coastal Chinook. These are called a squamish in certain areas, rooted in the direction of such winds coming down out of

Howe Sound Howe Sound (french: Baie (de /d')Howe, squ, Átl'ka7tsem, Nexwnéwu7ts, Txwnéwu7ts) is a roughly triangular sound, that joins a network of fjords situated immediately northwest of Vancouver, British Columbia. It was designated as a UNESCO Biosp ...

, home to the Squamish people, and in Alaska are called a '' williwaw''. They consist of cold airstreams from the continental air mass pouring out of the interior plateau via certain river valleys and canyons penetrating the Coast Mountains towards the coast. A similar, local föhn wind regularly occurs in the Cook Inlet region in Alaska, as air moves over the Chugach Mountains between Prince William Sound and Portage Glacier. Anchorage residents often believe the warm winds which melt snow and leave their streets slushy and muddy are a midwinter gift from Hawaii, following a common mistake that the warm winds come from the same place as the similar winds near the coasts in southern British Columbia, Washington, and Oregon.

References

{{DEFAULTSORT:Chinook Wind Climate of the Rocky Mountains Winds Natural history of Alberta Western United States Climate of Canada Föhn effect ml:കാറ്റ്#ചിനൂക്ക്