We'll first take a look at the North Atlantic Oscillation. The NAO is located in the North Atlantic Ocean near Greenland and we usually look at how it impacts our weather during the winter months.
The black line on this chart shows us observed data for the NAO. Currently, it is negative and has been that way for nearly a week. What this tells us is that we are in a blocking pattern thanks to an area of high pressure sitting near Greenland that isn't moving. This causes a trough to form over the eastern half of the United States that can't move anywhere thanks to the blocking from the high pressure near Greenland.
When we look at the forecast put out by the CPC for the Arctic Oscillation, we apply basically the same concepts to understand it.
WTVO Weather Intern