People who have spent some time in Montana tell eerie tales of the warm winter
winds. Have you ever experienced a chinook? If so, you surely remember
the sudden change in the weather. A dismal, gray, snowy day and
suddenly everything doesn’t look quite so bleak. A bit of sunshine
breaks through the dark cloud cover and the day begins to brighten. A
frigid cold day warms.
People who have spent some time in Montana tell eerie tales of the
warm winter winds. Have you ever experienced a chinook? If so, you
surely remember the sudden change in the weather. A dismal, gray, snowy
day and suddenly everything doesn’t look quite so bleak. A bit of
sunshine breaks through the dark cloud cover and the day begins to
brighten. A frigid cold day warms.
Chinook winds offer a welcomed respite from the long winter. In
Montana, Chinook winds are a fairly common climatic phenomenon that
delight and amaze both weather experts and residents alike. It begins
with the smallest whisper and grows as it whistles and dances down the
valley. A Chinook “wind is a blowing!?
At the turn of the century, the Calgary Herald wrote, “Those who
have not the warm, invigorating Chinook winds of this country, cannot
well comprehend what a blessing they are. The icy clutch of winter is
lessened, the earth throws off its winding sheet of snow. Humanity
ventures forth to inhale the balmy springlike air. Animated nature
rejoices”. (1900?Calgary weekly Herald)
A chinook wind, often just called “Chinook?, derives its name from a
word in the language of the Chehalis Indian Tribe. In their language
chinook means “snow-eater?. Aptly named, a chinook wind can melt over a
foot of snow in a single day and raise the temperature as much as 40
degrees in less than an hour. The snow melt is caused partly by warmer
temps and partly by the evaporation caused by the dry wind. Scientist
tell us that adiabatic warming of downward moving air produces the warm
chinook winds. Chinook winds are most remarkable in winter when the
warm winds contrast with the ambient cold air.
Moist weather patterns that originate off the Pacific coast cool as
they climb the western slopes and rapidly warm as they drop down the
eastern side of the mountain ranges. A chinook, or Fohn wind, begins
with a sudden change in wind direction, usually towards the west and a
rapid, dramatic increase in wind speed. I really don’t understand this
weather phenomena, but it feels wonderful.
Loma, Montana holds the United States record for the greatest
recorded temperature change. On January 15, 1972 the temperature went
from a nippy -56F (-48C) to a balmy 49F (9C) in less than 24 hours. In
a much smaller time frame, on January
11, 1980 the temperature at the Great Falls International Airport rose
from -32F to 15F in seven minutes as warm, Chinook winds eroded an
Arctic airmass. This 47 degree rise in seven minutes stands as the
record for the most rapid temperature change registered in the United
States.
Chinook winds often produce hazardous fire conditions. The warm wind
sucks the moisture from the air and any fires that may breakout are
vigorously fanned. The infamous Santa Ana winds are just another name
for a Chinook. Chinook winds are also called Cierzo or Mistral Winds.
Repeated or prolonged chinooks can be quite damaging to the
ecosystem of the forest. The dehydration caused by the warmth of the
Chinook wind can be dramatic and trees lose their winter preparedness.
The trees lose moisture through their needles and as the ground remains
frozen, there is no fresh water to replace that lost through
dehydration. Often the needles will then turn brown and die. This
condition is referred to as Red Belt. It is not a disease but a
reflection of a severe lack of moisture within the needles. White
Birch, like many other trees, cannot survive rapid temperature changes
and often die after a winter chinook. Often fruit trees and other
vegetation will “awaken? and start to spout tender buds that will be
destroyed by the next frost. An early spring chinook may destroy a
season’s crop.
Most Chinook winds are accompanied by a wide band of flat clouds
that hover at high altitudes. Native Americans call this the Chinook
Arch. Although these high clouds seem to hold the promise of rain, they
rarely bring a drop. Chinook winds actually deplete the forest and
fields of needed moisture. Viewing the Chinook Arch is often a
breathtaking experience for photographers and all those that appreciate
the artistic displays provided by Mother Nature. During a Chinook,
sunrise and sunset are profoundly beautiful as the sky is painted vivid
shades of fuschia, orange and red.
Soil not covered by snow is lost to wind erosion; flooding
conditions often occur due to rapid snow melt in the high country and
avalanche warnings abound.
The early settlers called these deep winter warm spells “false
springs? as the wild chinook wind will sometimes linger for several
days and it is easy to deceive one’s self that Spring is on its way.
However, when the chinook wind recedes, winter is back with all its
fury.
Chinook winds have profound psychological effects on many people.
Historical accounts tell of many people going “mad? when the Chinook
winds blow.Many are joyful for the relief from sub-temperatures, they
are energized and in general just feel better. Others will suffer
headaches, depression and nervous disorders. They are restless , anxious
and agitated. How do you feel when the warm wind blows?
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