Joe Lundberg

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Conflicting Signals

January 25, 2013; 10:48 AM ET

Friday, 11:30 a.m.

I'm going off the reservation today, heading off the beaten path. Some say I do that every day in my daily life, but that's a topic for another day! Instead of talking about the things right in front of us, such as the disjointed storms racing through the eastern third of the country with some relatively light snows, I will instead look longer term. And I'll look at it through a different lens than you may be used to.

Let me start by saying the very cold period we've been in this week from the northern Plains and Midwest to the mid-Atlantic and New England is the longest such period of cold in the past two winter seasons. By the time it fades on Monday, it will have rivaled a similar period of extreme cold back in the middle of January in 2009. Not record setting, mind you, but certainly well below normal.

And by now you're probably up to speed on how this cold gets turned around for a two- to three-day period, starting this weekend in the Mississippi Valley and ending next Wednesday along the Eastern Seaboard. The surge will be most impressive Tuesday from the Great Lakes to the Tennessee Valley and maybe a little less so east of the Appalachians on Wednesday ahead of a cold front.

You may even be aware of the cold that will be returning to the scene by the middle of next week, starting first in the northern Rockies and northern Plains, then spreading south and east with time later in the week. It has the potential to be every bit as cold as the current arctic outbreak has been, maybe even a little more so. And it may even be a little stronger and could be more widespread and longer lasting if things work out right. That's at least some of the ongoing thinking.

And there is some support for that. Let's look at a few things in support of it. First, the GFS ensembles for next Thursday:

Among the things you will note on that image is the very deep trough over the East at that time, and it is fully supported by the European and Canadian ensembles. There may not be much evidence of blocking in the North Atlantic, but that won't matter. Upstream there's a strong ridge just off the West Coast up into Alaska, with a strong northwest flow from northern Alaska and the Northwest Territories right into the base of that trough. You can make a good case of it being tied into a cross polar flow, too.

Let's go forward to Tuesday night of the following week:

Note that the largest negative height anomalies are almost all in eastern North America. The ridge off the West Coast is weaker, but there's still a west-northwest flow across Canada and the northern tier of states into the U.S., so if it is cold in northern Canada, which it probably will be still, that cold air should have no trouble surging into the U.S.

But how far south will the cold air be? A couple of weeks before this current outbreak, there were some concerns about a Florida freeze, or at least frost, into central Florida. In reality, it never got all that close. Gainesville slipped to 31 Wednesday morning, but Orlando never dropped to 40. And the rebound in temperatures along the central and western Gulf Coast has been quicker and stronger than had been anticipated. None of this is to say the exact same thing is going to happen with that next arctic outbreak next week and next weekend into week two, but it is something to at least think about.

Now let's look at the NAO forecast:

That's not very impressive, certainly not for blocking. It's not a signal that should draw a lot of excitement for big nor'easters on the face of it. Of course, many other factors go into the making of a nor'easter, but that's not the subject I'm looking at today.

How about the PNA:

Not really a strong signal there, either. A little dip this weekend, a modest rise next week, and that's it. Put those two together, and you wouldn't necessarily see the cold coming next week. Or perhaps you would see it, but not necessarily go off the deep end about it, especially the farther south you go.

But then you look at the European weeklies for week two, and they are filled with deep blue from Georgia northward to Quebec and northwestward all the way to Alaska. And the Canadian NAEFS 8-14 day temperature anomaly seems to agree:

But if you look at that closely, you see that Georgia and especially Florida westward along the Gulf Coast are NOT a part of that deep cold for that week long period. Could that be a signal to maybe back off on how widespread the cold will be the first week of February? Perhaps. Conflicting signals lead to some hesitancy on just how extensive this cold will be after the warm up early next week. It's coming, but how strong and how long?

The views expressed are those of the author and not necessarily those of AccuWeather, Inc. or AccuWeather.com

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About This Blog

Joe Lundberg
Joe Lundberg, a veteran AccuWeather.com forecaster and meteorologist, covers both short and long-term U.S. weather on this blog.