Tuesday, September 18, 2012

Record Low Arctic Ice May Play Crucial Role In Atmospheric Blocking Come Winter

A record low amount of ice in the Arctic could play a big role in how atmospheric blocking may evolve in the upcoming winter.

At the latest observation, ice in the Arctic was down to 3.5 million kilometers(squared). That seems like a lot, and you bet it is. But, when you see that the average for this time of year is hovering around the 5-6 million square kilometer mark, you can see that this is pretty unusual.

The lack of sea ice, in a cause-effect relationship, typically reduces the amount of cold air in the Arctic. The less cold air there is in the Arctic, especially in wintertime, the more negative the Arctic Oscillation tends to be. The Arctic Oscillation favors cold weather in the US when in the negative phase. Now, if the cold air has fled south into our neck of the woods, this means that there is a ridge of high pressure in the Arctic. Should this ridge happen to be close to Greenland, we could also see the North Atlantic Oscillation (NAO) drop into negative territory. This is plausible, considering the two are closely related. In the event the NAO and AO both go into negative territory, the East Coast is in a much better position for big Nor'easters to hit.

This has been proven to possibly be correct, as the NAO has had an unusually prolonged stage of negative values in the past summer, even to this day. The forecasts for the NAO are also still looking fairly negative, further giving life into the possibility that the lack of ice is to blame. Unless we see a rapid build-up of Arctic ice in the next few months, an abundance of cold air in our neck of the woods could very well play out. This, of course, depends on if the other indices in the atmosphere agree.


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