Signs Point To a Colder February
A month ago, I posted on the relationship of the Arctic Oscillation teleconnection to the colder weather we experienced in December. Essentially, when this indicator goes negative, you can expect colder winter weather in the Southeast, while when it’s positive, the weather is more likely to be warm and dry.
There is another teleconnection that can shed some light on likely winter weather patterns, the North Atlantic Oscillation. The NAO, as it’s called, measures the differences in unusual air pressure in the northern and southern Atlantic. When the index is positive, the eastern United States tends to have milder and wetter winter weather, while when the index is negative, the east coast tends to be colder, with more snow.
The graph below shows recent measurements of the NAO, along with the forecast for the next two weeks:
As you can see, the NAO has been in a positive phase since late December, corresponding to the milder weather we’ve seen so far in January. However, since the second week of the month, its effects have been getting weaker, and if you look at the second graph, which shows the 14 day predicted position, it should go into a negative phase soon.
The third chart shows the Arctic Oscillation prediction. After being in a positive phase in early January, it too is predicted to go negative.
While not as accurate as your typical three day forecast, these two teleconnections provide some indication that we may very well see more normal winter weather for February. The CPC’s 6 to 19 and 8 to 14 day outlooks through the first of the month still call for warmer and wetter conditions than normal through the first of the month, although the warm area shrinks in the longer-range forecast.
The weather service will issue its long range forecast for February tomorrow. It will be interesting to see what they predict.
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