High winds a major threat during winter
October 24, 2007
Craig — Gov. Bill Ritter has proclaimed this week through Saturday as winter weather preparedness week in Colorado. This is an excellent time for all individuals, families, businesses, schools, and radio and television stations to review their winter weather preparedness plans, according to a National Weather Service press release.
Two main causes of high winds in Colorado during the cold season are the air pressure difference between strong low pressure and colder high-pressure systems, and Chinook winds developing along the Front Range and mountains in the eastern half of the state.
A strong, low-pressure system in Colorado, coupled with a high-pressure system to the west, can send a cold wind, called a Bora, through the western part of the state and down the slopes of the eastern mountains. The result can be a cascade of high winds from the west or northwest into the adjacent plains at speeds of more than 100 mph. The damage caused by this event is usually much more widespread than that caused by a severe thunderstorm in the warm season.
Jet stream winds over Colorado are much stronger in the winter than in the warm season, because of the big difference in temperature from north to south across North America. Very swift west winds, under certain conditions, can bring warm, dry Chinook winds plowing down the slopes of the eastern mountains. These winds, sometimes called snow eaters, also can exceed 100 mph in extreme cases, again bringing widespread damage. Winds of 60 to near 100 mph are possible in and near the foothills in the Fort Collins, Boulder, Denver, Colorado Springs, Canon City, Westcliffe, Walsenburg and Trinidad areas. The area around Boulder is especially prone to these extreme wind events.
Dangers from high winds include flying debris, collapsed structures and overturned vehicles. The National Weather Service will issue a high wind watch when there is a chance for high winds to develop. When the threat becomes more certain in a specific area, a high wind warning will be issued. Cold strong winds can also bring dangerously low wind chill values, prompting a wind chill advisory or wind chill warning.
If high winds are forecast for your area, it is a good idea to bring lightweight belongings indoor or tie them down or move them so they do not become dangerous missiles. Any downed power lines should not be approached; instead call the utility company. Stay clear from buildings under construction during high winds. They can easily collapse. Traveling on north-south roads near the mountains during a high wind event can also be dangerous. If you drive a lightweight or high-profile vehicle, you may want to wait until the high winds subside.