I’m currently working on my January forecast, and I’ve about decided that I’m going to break it down into two parts: one focused on the first half of January and the other focused on the second half of January. This winter has been a tough one to forecast, and I’ve got a strong feeling that it’s going to continue to be a tough one to fully grasp. Regardless, it’s a great learning experience, and I learn new things every year.
I plan to explain why I still think that January and February are looking cold but will explain why the colder air will have a difficult time getting to the East Coast and particularly the Southeast at first. Mid to late January going into February looks particularly cold, but as you have likely learned by now, one variable can throw the entire forecast off. If everything seems a bit unclear to you right now, I’ll explain everything in detail in my next couple articles.
In this article, I want to do a little bit of a comparison between two months. One of those months was very warm across the eastern United States, and then a record-breaking Arctic blast hit the next month. If you haven’t figured it out by now, I’m talking about the January 1985 Arctic blast that shattered records, costing the U.S. billions of dollars in today’s dollars. Most people who were alive back then probably at least vaguely remember that historic Arctic outbreak, but I bet very few remember the unusually warm December that occurred across the eastern half of the nation right before.
There are many examples of winters (maybe not as extreme as January 1985) that started out warm and ended up cold later in January and February. I was wrong about the second half of December turning colder, but that doesn’t change the fact that there are several hints pointing towards things shifting much colder in January and February. If you look at what caused the January 1985 outbreak, it was the combination of a piece of the polar vortex breaking off and pushing into the northern United States and a cold high pressure pushing south bringing very cold air from the Arctic.
Here are the temperature departures from average for December 1984 vs. January 1985:
This is a surface map on January 20th, 1985 showing the strong 1048 mb high pressure over southern Canada, pulling in that cold, Arctic air into the United States.
Higher up in the atmosphere at the 500 mb level, notice a piece of the polar vortex down over the Great Lakes on January 20th, 1985. That’s very similar to how things looked last winter.
Let’s fast-forward to right now. This is at the 30 mb level (which is the stratosphere) on December 27th, 2014. Notice how strong and well-placed the polar vortex is. This is currently bottling up a lot of the cold, Arctic air.
By New Year’s, enough warming has occurred to begin displacing the polar vortex and elongating it.
By January 6th, you have two distinct vortices with the strongest piece located near the Hudson Bay.
What does all of this mean? If things play out just right, things could get quite cold later in January going into February. As always, I’ll keep everyone updated. Be sure to follow Firsthand Weather on Facebook.