There’s a cold snap on the way.
At least one town in Wyoming has set a new all-time low for the month of November, and that arctic air mass is now barreling its way toward New Hampshire.
While it’s unclear to what extent this cold actually is a piece of the polar vortex, that doesn’t mean the vortex isn’t an important driver of New England’s winter Climate. Experts are debating if more extreme swings from warm to cold are part of what a changed climate will look like in New England.
This will make meteorologists everywhere roll their eyes, but a really coarse way of understanding North America’s winter weather is as battle-ground between warm air in the tropics, and cold air in the arctic.
The jetstream is the front line of that battleground: on one side it’s cold, on the other it’s warm. The farther north or south of a given spot the stream moves, the warmer or colder it gets.
So for an idea of what wild fluctuations in the jet stream are like, here’s Boulder, Colorado, which recently had a huge southerly bulge in the Jetstream pass overhead.
“Boy, we had a glorious weekend,” says Kevin Trenberth, a climate Scientist National Center for Atmospheric Research. Though his weekend was nice, but there was almost a foot of snow on Wednesday. “A fifty degree drop in one day, and this morning when I was driving to work it was minus four degrees.”
Once that air gets to New England, it will have moderated some. Temperatures here will be 10 to fifteen degrees below average, but nowhere close to breaking records.
But you can’t have a cold snap these days without hearing the media (Public Radio included) start to talk about the polar vortex.
The vortex itself is a circulation patter in the upper atmosphere that spins like a halo around the arctic during the winter. In true polar vortex events, that halo begins to wobble, like a hula-hoop, and deform, and the cold air that it encircles is pulled down to the lower latitudes.
Whether this latest cold snap is really that kind of event is a matter of some debate. There are other ways the vortex can affects the Jetstream, that is often not the circulation pattern itself moving south.
This means that “in some ways everything and nothing can be attributed to the polar vortex this time of year,” says Eric Holthaus, meteorologist for Slate.
Click-Baiting or Educating
Really, the propagating use of the term polar vortex is a symptom of meteorology in the viral age. Holthaus himself has written about this latest pattern with another catchy weather phrase: he notes the cold will hang in place because of a lingering “omega block.” You can call it click-bait, but you can also argue this is just another way to get people interested in weather science.
And the jargon can be a convenient boogey-man too.
“When its forty degrees below-zero outside for weeks on end, people need something to blame,” says Holthaus.
Meanwhile, meteorologists don’t help the confusion by applying the term with differing levels of rigor.
“The Weather Channel has not used the term, and that’s unusual because weather.com is full of click-bait alarmism these days,” says Andrew Freedman, a science writer with Mashable. Some credit an article he wrote last year with triggering the viral catapulting of the term polar vortex into the main-stream. “Accuweather has been using the term, completely hinging its forecast by using it everywhere.”
Bleeding Edge of Climate Science
While the media works out how often it wants to use the word polar vortex, scientists are having their own, low-speed debate on what’s causing anomalies with vortex and if they are becoming more frequent.
Judah Cohen, a scientist with Atmospheric and Environmental Research, has shown that cold breaks out across the Midwest and Northeast more often whenever there’s a snowy October in Eurasia.
“Yeah, there was a lot of snow” this year, says Cohen, “It was the second highest that we’ve observed.”
But the climate is a complicated creature. Cohen says there’s no guarantee all that snow will result in big variations in the Jet Stream, it’s just an indicator, and indeed it’s not the only indicator. An academic with Rutgers made waves last year with a study connecting an unstable polar vortex with the melting ice around the North Pole.
But Trenberth, the climate scientist from Boulder, thinks that maybe the root cause is farther afield than either Siberia or the arctic.
“I think it’s much more than just about sea-ice. In fact I think some of the changes in the artic are a response, more than a cause,” says Trenberth. He think the increase in variability in the winter might have more to do with Ocean currents than anything else.
All of this science, he notes, is the bleeding edge of climate science. So while it might hint at a long-term trend, it’s still next to impossible to know much about what the weather in New England will do more than a few days out.