Weak polar vortex gives hints of what to expect this winter
Weak polar vortex gives hints of what to expect this winter
The term polar vortex has been thrust into the public consciousness over the last few years with media descriptions of very cold polar vortexes descending out of Canada into the Northern United Sta…
I work in the middle atmosphere and several things in this article I disagree with. First off, the polar vortex is a stratospheric and mesospheric jet stream that exists in the winter time. There is no polar vortex in the stratosphere during the summer. Let me repeat that. There is no polar vortex in the northern hemisphere right now! So how are you using it for predictions? Second, the media stole the term “polar vortex” for the Arctic jet stream that exists in the troposphere. Moreover, while correlations have been made (see Baldwin et al., 2021) on the stratospheric impact on the tropospheric weather, the physics aren’t well understood. Assuming you can make predictions on the northern hemisphere winter based on the polar vortex in the stratosphere (which again, doesn’t exist yet because it is summer) months out is unlikely.
Edit: I edited out the argument that the OP may not reputable since they are a meteorologist in Canada.
Edit2: I’ve edited my original post slightly after discussing this concept with the OP.
The polar vortex is present already and is slowly deepening. This is clearly evident in 10 and 30 mb height and wind charts.
Meteorological fall begins September 1. As noted, the polar vortex begins developing in August (because of the decreasing sunlight post-solstice) and isn’t full strength until later in the season. At this altitude in the poles (30 km up) thermal lag is less pronounced. Note the American Meteorological Society glossary says “the stratospheric polar vortex exists from fall to spring” (source). It is not just a winter phenomenon.
There is some predictive value in the strength of the polar vortex, especially with regard to the jet stream and sudden stratospheric warming events, but all seasonal forecasts carry uncertainty.
I am a meteorologist in Canada working primarily in the energy industry and have successfully used the polar vortex (among other parameters) in medium- and long-range forecasting several times. This has generally been in the context of deep troughs bringing heavy snow to Western Canada and the U.S. Northwest.
Of course, this being the internet readers can take or leave that claim. It was especially useful in early forecasts regarding an extreme cold weather outbreak in the U.S. Northwest in February-March 2019.
I don’t disagree with its usefulness as a potential predictor once it is formed. I’ve seen the literature on its impact on NAO and the AO. This is particularly true following sudden stratospheric warming events and its correlation with cold air outbreaks in the NH. However claiming that it is “weak” is misleading since it hasn’t formed yet. And to my knowledge, the physical mechanism of the interaction between the stratospheric polar vortex and the tropospheric jet has not been determined. We think it is related to wave reflection from planetary wave and gravity waves during a sudden stratospheric warming event. But if we don’t understand the mechanism, forecast or climate models are incapable of predicting them since that physics will not be included in the models. At this point, using the jet stream in the stratosphere (the unformed vortex) as a predictor for the NH winter will not be better than climatology.
I work in the middle atmosphere
The view from your office must be amazing.
Lol. After I wrote that I realized how it came off. Bad grammar.
This guy weathers.
Let me repeat that. There is no polar vortex in the northern hemisphere right now!
Not with that attitude!
/s
Thanks for posting, I always find meteorology fascinating and hungrily read up info posted from people like yourself. Please keep doing it, us buffoons that aren't trained really rely on people like you helping to cut through misinformation when it comes to weather and climate.
Check out this link to see what the actual polar vortex looks like:
https://earth.nullschool.net/#current/wind/isobaric/10hPa/orthographic=-60.71,59.02,169
This shows wind speed in the middle stratosphere. Since it is still winter in the southern hemisphere, you’ll find the polar vortex there. It is the very strong circular vortex surrounding the South Pole. The northern hemisphere doesn’t have one yet because it is still summer here. Hence my argument against claiming it is “weak” in the article. It simply doesn’t exist yet.
tl;dr: still up in the air, but expect more extreme swings, hooray climate change
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