Want a warmer outlook, take a look at Chinook
Story By: Jamie Smith
Source: KOAA
Published Wed Nov 19, 2008, 08:21 AM MST
Updated Wed Nov 19, 2008, 09:21 AM MST
These last couple of days have brought us record breaking temperatures and spring like weather for the Pueblo and Colorado Springs region. The two questions many of us have are what’s responsible for this beautiful weather and how long will it last?
As for the cause of this warm weather, you may have heard our KOAA 5/30 forecasters tossing the term “Chinook wind” around. A Chinook wind is a warm wind that comes down the eastern slope of the Rocky Mountains. As these winds flow down the mountain, the temperature of the wind increases. You might question why warm air is suddenly falling from the sky since we all know that warm air rises. In this case, the warm air is being pulled down the slopes by the circulation of a low or high pressure system that sits on the eastern side of the mountains.
We tend to hear a lot about these winds in the winter because a Chinook wind can cause a dramatic temperature increase from the typical weather. For example, a Chinook wind caused our recent weather in Pueblo to hit a record high of 77 degrees, which was a 24 degree increase from the normal temperatures for this time of year. How did we get this increase in temperature? As the Chinook wind flows down the mountain, it is subjected to increasing pressure, which causes the wind to warm. This warm air can then greatly increase the area’s temperature.
Chinook winds are also known as “thirsty winds” or “snow eaters”. This is due to the wind being very dry. A Chinook wind crossing over a heavy snow cover can melt and evaporate approximately a foot of snow in less than a day.
This type of wind is seen in another part of the United States which has been in the news lately. In California this phenomena is called the Santa Ana winds; and it’s these winds that have helped spread the wild fires in that state. Also, remember that these winds are both warm and very dry. Due to this, the winds will reduce the relative humidity in the area and dry out the vegetation. This causes the fire danger in the area to increase significantly.
As for how long will this beautiful weather last? Well, something to remember about these winds is that they are not permanent. Eventually the pressure systems will move on and the winds will die down. Then the fires in California will lose their best mode of transportation; and for us southern Coloradans, winter weather will return.
