The calendar may say it but certainly not what we’re seeing our there. Spring..or the lack there of. Just hasn’t been in the cards of late and not expected for the this entire week including the weekend! So, is there a computer model that could foretell longer than a week when Spring may be felt around here? Absolutely! And its name is NAO.
NAO stands for ‘North Atlantic Oscillation’ which monitors how the jet stream fluctuates. The NAO is a see-saw in weather systems in the North Atlantic. The weather systems include a low positioned around Iceland and the high around the central Atlantic. It has two states..positive and negative. They bring very different weather across our local area as well as most of the country.
The negative phase occurs when the low and high are weak creating a low zonal flow across the US and North Atlantic forcing more cold to filter over the Midwest and east with the west experiencing the warmth. On the flip side, the positive phase happens when the Low over Iceland and the High over the Atlantic strengthen to expand and strengthen creating a zonal flow and thus brings our share of warmth as well as the eastern half of the United States. Thats the change we root for. Graphically, we can analyze the negative and positive phases that go on with this oscillation with the help from the good people at the Climate Prediction Center. Here is the latest.
This shows how the NAO has behaved this winter but more importantly what is expected for the rest of March. The red lines (the far right) are a collection of models related to the NAO that indicates if its expected to go negative or positive. As you can see, its trending on spring temperatures to be delayed through March (more negative).
I know what you’re thinking. “So, when is it going to feel like Spring around here?” Here a sign. The latest GFS 1000-500 Thickness does show the red lines of higher heights (warmer air) to move in around the 29th of this month and thus pushing the below normal temperatures back into Canada.
Lets hope that translate through Easter and beyond. The NAO will let us know. (Insert mystery music).