-NAO to Intensify This Week, Arctic Outbreak To Move Into the US

We are how at the peak of the winter season here in early February and so far it has proved to be very interesting across the United States.

When our weather team presented the Winter Outlook back in November, we highlighted at the potential of high latitude blocking to influence our weather pattern at some point in the winter. The signs of a Greenland Block began to appear just after Christmas and it came to verification at the beginning of the New Year. The one thing we didn’t count on was the Greenland Block becoming as persistant as it has been the entire month of January.

Even with the calendar turning to February there are no signs of the Blocking pattern to give way, infact we see an re-intensification of the North Atlantic Oscillation later this week. This intensification of the -NAO combined with a bit favorable pattern in the Pacific is going to unleash the coldest air of the winter into the US late this week including the Carolinas by this weekend…

Posted below is a graph of the NAO through the middle of February. As you can see the teleconnection will go strongly negative over the next seven days. The -NAO in connection with a favorable Pacific can bring a favorable winter pattern to the Eastern and Southern US.

A look at the 500mb weather pattern starting later this week clearly shows the West based -NAO near Hudson Bay. That will force northwest flow from the Arctic Circle straight into the United States. One big difference this go around is the southeast ridge that was in place about a week ago is no longer there. That means the discharge of cold air will be forced southeast rather than toward the Western US…

500 mb 5-Day anomalies (Thur Feb 4th -Tue Feb 9th)

If you click on the video below it clearly shows the extensive cold that will drop down late week and bottom out across the Southern part of the country…

GFS 850 mb temperatures

The latest Ensemble Mean temperatures indicate a very cold pattern coming up starting this weekend and going well into next week. The worst of the cold appears to arrive Sunday-Tuesday

The Ensemble Mean of course is the average of all ensemble members, individual members along with the Operational run of all the global models indicate that some of the coldest air since early 2017 and 2018 could arrive next week. Our current 7-Day Forecast ends on Monday and you can see the potential of just how cold it will be.

Looking at the Ensembles the -NAO will persist well beyond the current forecast frame and signs of another load of bitter cold may be on the way by Day 10 or so…

So the question for many winter weather fans is…can we get snow to go along with the cold?

While there is no current threat of significant winter weather, the pattern is supportive if we can get a wave of low pressure to fling moisture over the approaching cold airmass. And even if we can’t…there are likely to be features in the jet capable to overrun moisture once the first surge of cold air passes through. This will be something that our weather team will monitor this week.

Regardless, get ready for a 48-60 run of cold air that could leave a good part of the coverage area in temperatures at or below freezing. Be prepared for impacts from the cold…

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