Chinook Wind

Chinook winds have been observed to elevate midwestern Winter Temperature s, 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".

CHINOOKS IN ALBERTA

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 not as common north of Red Deer , although they can and do occur as far north as Grande Prairie in northwestern Alberta and Fort St. John in northeastern British Columbia .

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. In Canada, 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 is also well known for getting many chinooks, 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 77 kilometers (48 miles) 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 bitterly 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

One of the most striking features of the chinook is the chinook arch, which is a band of stationary Stratus Cloud s 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.

The stunning colors seen in the chinook arch are quite common. Typically the colors will change throughout the day. Starting with yellow, orange, red and pink shades in the morning as the sun comes up. Gray shades in the mid day, changing to pink/red colors and then changing to orange/yellow hues just before the sun sets.

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Chinook Wind