Cold Start to MarchFebruary 27th, 2013 at 11:09 am by Greg Shoup under Weather
Negative North Atlantic Oscillation
Last week I blogged about a tropical oscillation which would bring two more large tropical waves from the eastern pacific across our area. Well, we saw wave one Tuesday and it appears that wave two will be here in a week with another snow storm possible.
The oscillation that we are looking at here is a much more prominent one that is active all winter long and has a dramatic effect on our weather pattern. For instance, if we have a negative NAO which is predicted by the Ensemble Model 6 to 10 day model outlook cold air is released across the eastern third of the United States.
This is the pattern that a negative NAO creates. A strong or tight gradient is created between high and low pressure which causes the release of wet weather for the western U.S. and cold weather for the east.
Here is another diagram to show the effects of a Negative Atlantic Oscillation across the eastern U.S. As cold air is ‘drained’ southeast from Canada to Alaska. This creates much below average temperatures for the eastern U.S.
In other words, it will most likely be a very cold start to the month.