The Polar Vortex hurt. We who lived in it, through it, with it, are like farm animals that got zapped by the electric fence a couple of times … notice all that long grass growing by the fence. Stay away. It hurt! So we are worried that this will happen again.
It is a reasonable worry, from a scientific point of view. The Polar Vortex visitation last winter was the result of changes to trade winds and jet streams that has characterized our weather for the last few years. One of the big questions on my mind is this: Are wavy jet streams and corresponding changes in the distribution of excessive rainfall and drought likely to become spatially patterned? In other words, is it likely that when the Polar Vortex wanders that it will tend to wander to the same small set of locations, like Siberia or North America? So far this seems to be at least partly true. The drought in California has not been maintained because of a lack of rainfall at that latitude, but rather, a lack of certain seasonal precipitation (winter snows) at that longitude, because of the oft-cited “ridiculously resilient ridge” which is actually one of several standing waves in the polar jet stream that shunts wet air around California, to places the Midwest. It is conceivable that the Polar Vortex, as part of the climate change induced “new normal,” will wanter off-pole and onto a landmass (either Eurasia or North America) often-ish, from now on, or until continued global warming results in some other pattern which we’ll probably call “New Normal 2.0”.
This is a question I’ve asked various scientists who are working on this problem. The answer I’ve gotten so far has been, paraphrased, “Yeah, I don’t know, maybe, we’re thinking about that. Get back to you later.”
But there is hope. I’ve put links to three places you can go for more discussion and information below. Here’s the tl;dr. The National Weather Service does a very good job of predicting what winter will be like in North America, but the accuracy of that prediction, unsurprisingly, drops off month by month. So the current prediction is probably pretty good for November/December, but as January and February come along, what is predicted now may be off. With that caveat, these are the salient predictions:
1) There will not be a Polar Vortex excursion into North America. Probably. The thing is, if this is a recent phenomenon and increasing in likelihood, the predictions may be off, but there are good reasons to believe they are not. Don’t assume the Polar Vortex will visit us, but don’t sell your wool pants at that last garage sale of the year.
2) California may actually get some rasonable precipitation this winter. It is hard to say if it will be drought-breaking rain, but it may help.
3) Although winter seems to be starting early this year (with many inches of snow having fallen or about to fall on the Front Range, the Dakotas, etc.) the overall prediction is a somewhat warmer than average winter for most of North America.
4) The Southwest, California, Texas, North-Central Mexico will have a bit more moisture than average, but other than Pacific coastal Mexico, not a lot more. That won’t translate into huge snowfalls except at high elevations. The middle of the country, from Montana to western Ohio and Michigan, south to a line running from southern Idaho across to Florida, including the Southeast, will have average precip. So, Minnesotans may see early snow if it remains cool, but this will not be an exceptionally snowy winter. Less than usual moisture is predicted for Kentucky, Ohio, western Pensylvaina, parts of New York and most of New England. But, this is only a small amount, so don’t sell your snow blower at that garage sale.
Parts of the Pacific Northwest and inland across to western Montana may be a bit dryer than usual.
Overall, temperature wise, no region is expected to be especially cold, mostly somewhat warm. The regions of Canada and Alaska along the Arctic Circle will be very warm (relatively … so many degrees below zero instead of many more degrees below zero) as we would expect with “Arctic Amplification.” Moisture levels, overall, are not going to be extreme in either direction anywhere, though the dry in the Northwest may be noticeable.
In other words, the average person’s perception of weather, which varies from reality a great deal, will include the actual realized variation, if the predictions hold up.
The NWS predictions can be found via this page.
Eric Holthaus has a discussion of the coming winter here.