Cold Waves Could Be Blamed On The Arctic Oscillation

You may have already heard meteorologists and forecasters talk about La Nina and El Nino changing weather patterns around the world. Now it looks as though we have another player in the global  patterns that effect the weather here in Colorado and across the United States.

It's the Arctic Osillation or AO for short. The AO is simply put, a ribbon of strong winds that blow from west to east around the North Pole. When these winds are in what is called the "positive phase" they are at their strongest and tend to corral the coldest of the Arctic air and moisture over the extreme northern part of the United States up into Canada. So most of the big , cold , snowy Arctic storms tend to hit from Alaska eastward across Canada out toward Scotland and Scandinavia. Normally, in this "positive phase", the western U.S., Rocky mountain region, East Coast out into the Mediterranean tend to have drier and relatively warmer winters.

This year the AO is in a strong "negative phase" with weaker winds circulating the North Pole. This opens the door for polar storms to blast farther south into the mid-section of the United States and farther south in lattitude around the world. This may be one of the reasons for the wild weather we have seen this year, such as:  the flooding in California early in the season, the bitter cold and big snows that have plauged the eastern seaboard. Wild weather has even pounded parts of Europe with record breaking cold waves, Parts of China have measured some of deepest snow they have seen in almost 60 years.

This year it seems to be a combination of a strong La Nina (cooling ocean water of the west coast of South America) and the Arctic Oscillation that has created the crazy weather patterns of the season so far.

So hold on, we still have a lot of winter left to make it through!