Well, looks like the news media has found a new word to latch on to and repeat about a billion times with dramatic music scores. Polar Vortex! In some cases, you might think you are watching the Sci Fi channel the past 24 hours and that a sharknado is on the way too.
POLAR VORTEX IS NOT A HURRICANE
This discussion is not to prove nor discount global warming or to pick sides. This discussion is about putting out some facts for all of you out there. Frankly I decided to write this post after one “weather commentator” on NBC claimed that the Polar Vortex is an arctic hurricane. For a second I thought I heard this wrong. Maybe I was having an ear infection come on. However, this commentator (not a meteorologist by the way) stated just that.
Let me explain why a comment like this is irresponsible. Look, we all know the average person out there is not going to know the difference between a hurricane and an upper level low. As someone who presents science to the public, you should be careful with what terms you use. Let’s say they have a doctor on TV discussing headaches. If this doctor said headaches are like brain heart attacks, you would have a huge uproar. The statement is not only incorrect, it’s insanely stupid. My point is that when someone hears heart attack, they think of life and death situation. In this case, when the average person thinks of a hurricane naturally thoughts of Katrine, Sandy, and other powerful TROPICAL storms come to mind. The Polar Vortex is none of these features.
The Polar Vortex is a cold core semi-permanant 500 MB low pressure system. The Polar Vortex (PV) is a natural feature in the atmosphere at both sides of the Poles that retreats towards the Arctic and weakens in the Summer and drops south and typical strengthens in the winter. The Polar Vortex is a result of the atmosphere balancing out the natural temperature gradient from the Mid Latitudes to the Higher Latitudes. You can NOT see the Polar Vortex. The Polar Vortex is on average about 5,000 feet up in the air. If anyone lives at 5,000 feet you have more problems than worrying about the Polar Vortex, but yes you’d be dealing with a rather wicked wind event up there.
On the other hand, a hurricane is a low level, as in at the surface, warm core low that can expand up to 1,500 to 3,000 feet in the atmosphere. A tropical cyclone is compact and small compared to the Polar Vortex (PV) and is far more intense. The process that drives a tropical cyclone is the release of latent heat energy via high levels of water vapor. The pressure gradient that is produced in this process leads to intense winds and heavy rain in generally a limited location. It should be noted that at 500 MB, HIGH PRESSURE is found as water vapor cools and is drive out of the circulation. In other words a hurricane and a Polar Vortex are the polar opposites in the weather word and never shall the two meet. They physically can not exist in the same location. The Polar Vortex is an upper level low pressure system. A tropical low is at the surface to roughly 700 MB at most.
IS THE POLAR VORTEX DEADLY?
The short answer is no. When the Polar Vortex drops south, as it does every winter going back to the start of our climate system going back thousands of years, the cold air that is driven south at the surface CAN be deadly. There is no doubt about that. Much like what was seen in 1896, with the Polar Vortex over Quebec, the 500 MB pattern supports the transport of Arctic air from the North Pole right into the United States. This winter with an above normal snow pack and ice coverage in the Arctic and Siberia, these air masses have been rather strong. This was warned back in October in the Winter Forecast. Let me state that again. The potential for these types of air masses were warned about back in October given the NATURAL process of snow growth and rapid ice build up in the Arctic.
So while the air masses that can be drawn south can be deadly, the actual Polar Vortex which by the way is in Quebec right now, is in itself deadly.
WHAT CAUSED THE POLAR VORTEX TO DROP?
The Polar Vortex dropped south due to developments observed back in early to mid December. A stratospheric warming event developed over North America and the northern Atlantic leading to a powerful winter storm over northwestern Europe. This storm caused the jet stream to buckle, allowed above normal 500 MB heights or a ridge to build over the Arctic, and forced the Polar Vortex to the south. The video below details what was going to happen and was seen by Premium Members back on December 10, 2013. This is a 20 minute video but specifically details EXACTLY why we are cold right now and why there were stormy conditions the past few weeks. This is simple physics and meteorological law and I invite you to watch!
IS THE POLAR VORTEX DROPPING SOUTH DUE TO GLOBAL WARMING?
Okay, I guess I’d have to tackle this sooner or later. No one can really say with complete certainty that climate change, natural or man made, is the large scale driver in all of this weather.
The theory is as such. Melting in the Arctic leads to more water than ice which creates a greater thermal gradient at the Polar regions rather than the Mid Latitudes. The result of this leads to a weaker jet stream and thus peaces of the Polar Vortex weaken and break off.
There IS some validity to the theory. However, I should point out that each time we see these patterns unfold like in the 1960’s, 1940’s, and late 1890’s (like in 1896), another feature that is discussed in this theory shows up. Namely the AMO or Atlantic Multidecadal Oscillation. The AMO and the Pacific version, PDO, are phases in the Ocean where temperatures waver to above normal and below normal sea surface temperatures. You’ll note that when the AMO is in a positive phase, which is warm, that the potential for high latitude blocking increases. The Arctic Oscillation is more likely to be negative and also is the North Atlantic Oscillation is like to be negative. When these two features are in a negative phase, the Arctic tends to be warmer and the mid latitudes where we live are colder. As such, the warmer conditions WOULD lead to more melted ice.
Is Global Warming enhancing this natural fluctuation? Perhaps. We don’t really have data either way to say anything conclusive as clearly more research needs to be done on Ocean Dynamics.
However, the theory that less ice in the Arctic caused THIS event is just not born in facts as we have had a rapid increase in ice, the largest in 30 years over the Arctic. This event is driven by stratospheric warming and the evolution of the influence of the very warm waters in the North Pacific forcing a ridge around the Barring straits and eventually into the Arctic.
So in closing. This isn’t the end of the world and you will see this event again and again each winter like every winter. This air mass is especially cold, no doubt about that. However, we have seen similar Arctic Outbreaks going back to when we recorded data, as far back as the 1800’s and you can beat we will see them again.
In short, don’t let the hype get to you. Stay in doors, get some hot chocolate, and don’t worry. This cold air will past. In six months I’ll likely have to write about a heat wave and someone will ask me where all the cold air is. It’s in the Arctic because it’s June and that means Summer.