So we got a Chinook in today, funny things those. They come in and are very windy but make the world a very warm place. Prior to the Chinook it was -42 with the windchill. (This was around Wednesday) and today it's +10 with winds from the West. How weird eh? It's so true what they say about Lethbridge, if you don't like the weather wait five minutes. LOL
For you non-Albertans out there here's the scientific logic behind a Chinook:
"Chinook winds, often just called chinooks, are a
wind pattern observed in midwestern
North America, named for the
Chinook Indians. In popular myth, Chinook is supposed to mean "snow eater", as a strong Chinook can make a foot of snow all but vanish inside of one day. The snow partially melts, and partially evaporates in the dry wind. The true origin of the name is that "Chinook Wind" in the local argot of the
fur trade era meant that the wind came from the direction of the country of the Chinooks (the lower
Columbia River, i.e. from across the
Rocky Mountains.
Chinook winds have been observed to elevate midwestern
winter temperatures, often from below −20°C (−4°F) to as high as 10°C to 20°C (50°F to 68°F), for a few hours or days, at the end of which, the temperatures plummet to their base levels.
One of the most dramatic examples of the chinook winds occurred on January 15, 1972, in
Loma, Montana. The temperature rose from −47°C (−54°F) to 9°C (49°F); the greatest temperature change ever recorded during a 24-hour period.
A "Chinook Wind" or simply "a Chinook", mean the reverse on the
British Columbia Coast and
Puget Sound and-
Straits of Juan de Fuca, bringing warm, west
southwesterlies - "from the Country of the Chinooks"."
http://en.wikipedia.org/wiki/Chinook_windChinooks in Alberta"Where chinooks occur most frequently Chinooks are most prevalent over southern
Alberta in Canada, especially in a belt from
Pincher Creek in the
Crowsnest Pass through
Lethbridge, getting 30 to 35 chinook days per year on average. Chinooks become less frequent further south in the United States, and chinooks are rare north of
Red Deer.
In most recent winters (since the 1980s), chinooks and warmer weather have all but banished winter to just a few spells of sharp cold of one or two weeks, and some midwinter months have averaged high temperatures over 5°C (41°F), similar to the West Coast of
British Columbia, where Canada's warmest winters are found.
In southern Alberta, most of the winter can be spent with little or no snow on the ground.
Calgary can expect a white Christmas about 59% of the time. Only the West Coast of British Columbia and southern Ontario have fewer white Christmases than southern Alberta.
In Lethbridge, chinook winds can gust in excess of hurricane force (120 km/h or 75 mph). The winds gusts can be strong enough to shatter car windows through air pressure differential. On November 19, 1962, the winds there gusted to 171 km/h (107 mph) in an especially powerful chinook.
In Pincher Creek, the temperature rose by 33°C (60°F) in one hour in
1962. Also, trains have been known to be derailed by chinook winds there. Calgary gets many chinooks as well, but the wind is usually not very strong. In February
1992,
Claresholm, Alberta hit 24°C (75°F) — one of Canada's highest February temperatures.
Chinooks versus the Arctic air mass
In mid-winter, the chinook can seem to do battle with the Arctic
air mass at times. It is not unheard of for people in Lethbridge to complain of −20°C (−4°F) temperatures while those in
Cardston, just 40 minutes down the road, enjoy +10°C (50°F) temperatures in shorts and T-shirts. 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.
It has been reported on a local TV historical program that many years ago Cardston once reported a curtain of fog remaining over Main Street for many hours. The west side of town was balmy with melting snow, while the east side of town was bitter cold.
In Calgary, recent winters have seen situations where the
airport in the northeast part of the city is reporting around −20°C and the southwest part of the city is sitting at +7°C (45°F).
Chinook arch over Calgary, January 6, 2003
Chinook arch:
One of the most striking features of the chinook is the chinook arch, which is a band of stationary
stratus clouds caused by air rippling over the mountains. To the those unfamiliar to the chinook, the chinook arch may look like a threatening storm cloud at times. However, they rarely produce rain or snow. They can also create stunning sunrises and sunsets.
How chinooks occur:
The chinook phenomenon results from the movement of
high and
low pressure systems over the
Rocky Mountains. As the wind moves over and through the mountains, the moisture in the air condenses, warming the air by releasing
latent heat. Then, as it moves downhill, the cold air above presses down upon it, resulting in further warming through
adiabatic compression.
Quite often, when the West Coast is being hammered by rain, the
windward side of the
Rockies is being hammered by snow (as the air loses its moisture), and the
leeward side of the Rockies in Alberta is basking in a chinook.
Two common cloud patterns seen during this time are:
A chinook arch overhead and/or A bank of clouds obscuring the mountains to the west. It would appear to be an approaching storm, but it does not advance any further east.
The Manyberries chinook:
Often, a chinook is preceded by a "Manyberries chinook" during the end of a cold spell. This southeast wind (named for a small village, now a hamlet, in southeastern Alberta, from where the wind seems to originate) can be fairly strong and cause bitter
windchill and blowing snow. The wind will eventually swing around to the southwest and the temperature rises sharply as the real chinook arrives."
http://en.wikipedia.org/wiki/Chinook_wind#Chinooks_in_AlbertaNow if you're really lucky someday I'll tell you about another thing dear to an Albertans heart, the coulee... LOL
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