Greetings from Southern Connecticut Weather!
Looking back to last winter, one of, if not the biggest buzzwords that we saw during the winter was the Polar Vortex, often known as the PV in the meteorological world(and what we will call it for the purposes of this discussion). One would see articles like these on a daily basis that the PV was going to form over the US and bring bitterly cold air to the country, and it was made to seem like the PV forming was a “once in a lifetime” event.
Looking back to last winter, one of, if not the biggest buzzwords that we saw during the winter was the Polar Vortex, often known as the PV in the meteorological world(and what we will call it for the purposes of this discussion). One would see articles like these on a daily basis that the PV was going to form over the US and bring bitterly cold air to the country, and it was made to seem like the PV forming was a “once in a lifetime” event.
The hype coming from the media at the time was bordering on ridiculous, and we heard a lot of misguiding and flat out wrong information about what the PV actually was. As our first cold shot of the winter looks to approach later next week, the PV talk is back and worse than ever, and so we decided to write a little piece about what the PV actually is, some common misconceptions about it, and how it actually plays into our weather.
First, let’s define what the Polar Vortex actually is. In it’s simplest definition, the PV is the pattern of winds around the north pole, which generally serves to create a pool of very cold air in those extreme northern latitudes. It is seasonal, being much stronger in the winter than it is in the summer. It is formed in the fall by the increase in wind speed during the fall in the polar regions, causing the potential vorticity to increase and the overall circulation to move further north into the polar regions. As the winter approaches, the wind speed slows down and as a result the temperature of the air in the Polar Vortex cools and the growth ends. As the winter comes to an end, the wind speed begins to increase again, warming up the vortex once more and eventually breaking it up, marking the transition from a winter like climate to a spring like one. This transition can take place anywhere from March to May, depending on the year and influencing factors in the pattern.
Now that we know what the Polar Vortex is, we can look at how it influences our weather patterns. The primary influence that the PV has on our weather pattern is providing shots of arctic air for the northern tier of the CONUS when a piece of the PV breaks off from the main cyclone of winds and drops south as a result. This is seen in this map from the EURO model from last January, where you can see a piece of the PV has broken off from the main cyclone over the arctic and has dropped down to Ontario and over the Great Lakes, bringing very cold air relative to normal for the Midwest and East.
Now that we know what the Polar Vortex is, we can look at how it influences our weather patterns. The primary influence that the PV has on our weather pattern is providing shots of arctic air for the northern tier of the CONUS when a piece of the PV breaks off from the main cyclone of winds and drops south as a result. This is seen in this map from the EURO model from last January, where you can see a piece of the PV has broken off from the main cyclone over the arctic and has dropped down to Ontario and over the Great Lakes, bringing very cold air relative to normal for the Midwest and East.
When the PV does impact the US, it’s usually first seen in the Midwest and northern plains, where the actual lobe drops down, and then gradually, the cold air works it’s way east and moderates as it does so. The PV dropping down is tied to the speed of the winds in the PV, the slower the speed, the less resistance is met by the cold air that is attempting to drop down and as a result, the more likely it is for a lobe of the PV to break off. The current state of the wind speeds are measured in part by the AO(Which measures several other things as well, for more, see the SCW Winter Outlook), with a –AO being associated with weaker relative to normal and a +AO being associated with stronger speeds than normal. As a result, a –AO is correlated with colder temperatures, and also more frequent sightings of the PV in the CONUS, which is why when signals are there for a –AO to develop, long range forecasters will often hedge towards a colder pattern setting up. Here's two representations of the PV, the first with a stronger windspeed and as a result the PV being contained mainly to the Arctic Circle, and the second with a weaker windspeed and as a result the PV being allowed to drop down into the CONUS.
The biggest impact that we see from the PV when it impacts us is well below normal temperatures as a result of the arctic air that funnels in as a result of the displaced PV. Keep in mind though that the PV isn’t the only way to be below normal temp wise, and in fact, is one of the rarer ways that we are below normal, although it is often the cause of our greatest anomalies. The positioning of the PV can also provide blocking for storm systems, causing them to track in a certain direction, which can impact the sensible weather that we see as a result. Unrelated blocking in the atmosphere can also push the PV further south and make movement into the CONUS more likely. On rare occasions, one will see a lobe of the PV phase with a storm system, usually bringing much colder air with that system and a stronger system as well as a result of the added energy, but that is comparatively rare compared to the more common phasing of the northern and southern streams.
Now that we know what the PV is and how it influences our weather, let’s take a look at some common misconceptions about it.
· The Polar Vortex is something new.
False. The Polar Vortex has been around since the beginning of time, and while it’s only become a buzzword in the last year or two, meteorologists and forecasters have been using it for decades to help them with their forecasts.
· The Polar Vortex is caused by global warming/climate change
Questionable. The PV has been impacting us long before climate change became a major issue, but some suggest that climate change will lead to more extremes in our weather patterns, which could include more visits from the Polar Vortex. There’s no official correlation between the two as of yet, but the idea is out there. However, attributing any one visit by the Polar Vortex to climate change or using it as evidence for global warming being real has no scientific backing and is simply political posturing.
· The Polar Vortex is evidence that climate change is a hoax.
False. See above re. any single visit of the Polar Vortex.
· The Polar Vortex is responsible for all the cold air we see.
False. While the Polar Vortex is often involved in our biggest cold shots, there are plenty of other ways to have below normal temperatures, and in fact the lions share of cold weather that we see has nothing to do with the PV.
· The Polar Vortex is the reason why we had a cooler than normal summer.
False. As we explained earlier, the PV is very weak in summer and as a result has little to no impact on our weather.
· The Polar Vortex is a harm to our society.
Questionable. Cold weather can have adverse effects, but there’s no difference between cold air from the Polar Vortex and from anywhere else. As long as one dresses appropriately for the cold and limits their time outside during extreme cold(just like what one should do in any cold snap), the PV is harmless.
Hopefully, this piece has helped you understand a little more about what the Polar Vortex actually is, how it impacts our weather, and cleared up some of the common myths surrounding the polar vortex. As always, we love questions, so if you’ve got some, or just have something you want to say, sound off in the comments of this post below (Click comments to the right of the title if you can’t see it) and we’ll get back to you as soon as we can! If you enjoyed this, we’d also really appreciate it if you shared the link to it on Facebook with your family and friends to help us combat the misinformation and hype that’s out there from the media.
Thanks for reading, and stay warm this winter!
-SA
Now that we know what the PV is and how it influences our weather, let’s take a look at some common misconceptions about it.
· The Polar Vortex is something new.
False. The Polar Vortex has been around since the beginning of time, and while it’s only become a buzzword in the last year or two, meteorologists and forecasters have been using it for decades to help them with their forecasts.
· The Polar Vortex is caused by global warming/climate change
Questionable. The PV has been impacting us long before climate change became a major issue, but some suggest that climate change will lead to more extremes in our weather patterns, which could include more visits from the Polar Vortex. There’s no official correlation between the two as of yet, but the idea is out there. However, attributing any one visit by the Polar Vortex to climate change or using it as evidence for global warming being real has no scientific backing and is simply political posturing.
· The Polar Vortex is evidence that climate change is a hoax.
False. See above re. any single visit of the Polar Vortex.
· The Polar Vortex is responsible for all the cold air we see.
False. While the Polar Vortex is often involved in our biggest cold shots, there are plenty of other ways to have below normal temperatures, and in fact the lions share of cold weather that we see has nothing to do with the PV.
· The Polar Vortex is the reason why we had a cooler than normal summer.
False. As we explained earlier, the PV is very weak in summer and as a result has little to no impact on our weather.
· The Polar Vortex is a harm to our society.
Questionable. Cold weather can have adverse effects, but there’s no difference between cold air from the Polar Vortex and from anywhere else. As long as one dresses appropriately for the cold and limits their time outside during extreme cold(just like what one should do in any cold snap), the PV is harmless.
Hopefully, this piece has helped you understand a little more about what the Polar Vortex actually is, how it impacts our weather, and cleared up some of the common myths surrounding the polar vortex. As always, we love questions, so if you’ve got some, or just have something you want to say, sound off in the comments of this post below (Click comments to the right of the title if you can’t see it) and we’ll get back to you as soon as we can! If you enjoyed this, we’d also really appreciate it if you shared the link to it on Facebook with your family and friends to help us combat the misinformation and hype that’s out there from the media.
Thanks for reading, and stay warm this winter!
-SA
