Post 00919
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The Chinook blows occasionally over the Northwest during the five colder months of the year. Though of brief duration, these winds are very efficacious in softening the asperities of winter with their moderating warmth, and they are of great assistance to the stock and other interests. Apparently the Chinook starts from the Pacific, in the extreme Northwest, warm and heavily moisture-laden. Sweeping eastward, it is chilled in crossing the mountains, on which it speedily releases its moisture in heavy snowfalls. Warmed through releasing moisture, it is still further warmed through compression while descending the Cascades, and it goes forward extremely feverish and thirsty. It now feels like a hot desert wind, and, like air off the desert’s dusty face, it is insatiably dry and absorbs moisture with astounding rapidity.
It may come from the west, the southwest, or the northwest. Its eastward sweep sometimes carries it into Wisconsin, Iowa, and Kansas, but it most frequently floods and favors the Canadian plains, Oregon, Washington, Montana, Idaho, Wyoming, and Colorado. It may come gently and remain as a moderate breeze or it may appear violently and blow a gale. Its duration is from a few hours to several days.
There are numerous instances on record of a Chinook greatly raising the temperature, removing several inches of snow, and drying the earth in an unbelievably short time. An extreme case of this kind took place in northern Montana in December, 1896. Thirty inches of snow lay over everything; and the quicksilver-tip in thermometers was many lines below zero. In this polar scene the Chinook appeared. Twelve hours later the snow had entirely vanished! The Blackfoot Indians have a graphic term for this wind,–“the snow-eater.”