Sudden Stratospheric Warming Triggers Severe Arctic Outbreak

February 22, 2023

Here we are in late February, and we are seeing an arctic outbreak in North America, just like last year, and the year before. If I’m understanding correctly, the current one is connected with something called a Sudden Stratospheric Warming. (SSW)

I’m just going to point anyone that wants to do a deeper dive to this post by Severe Weather Europe.
It’s long and deep, with a very cool animation, or 2, but key points here.

Severe Weather Europe:

A strong Stratospheric Warming event is currently active. It has brought a major disruption of the high altitude circulation and is set to impact the lower levels. Looking ahead, we can already see this event’s first major weather impacts across North America and Europe.

The Sudden Stratospheric Warming event (SSW) is now here, and it is leaving a strong mark on the Polar Vortex and the atmosphere. You will see the latest atmospheric conditions with the active SSW and the Polar Vortex breakdown.

But we will focus more on its actual weather impacts, already seen in the forecast. The most prominent effects are currently trending towards the North Atlantic and over Greenland, impacting the entire North American region and Europe

To understand what is currently happening, we must know what the Polar Vortex is. In simple terms, it is a single name that describes the broad winter circulation over the northern (and southern) hemispheres.

Below, you can see a 3-dimensional image of the Polar Vortex. The vertical axis is greatly enhanced for better visual presentation. In addition, you can see the actual structure of the Polar Vortex, connecting down to the lower levels to the pressure systems.

Posting this again, Nebraska State Climatologist Martha Shulski and MIT’s Judah Cohen on the increase in polar outbreaks during this late winter time window.

The Polar Vortex extends high up into the atmosphere. You can see the atmospheric layers in the image below. The lowest level of the atmosphere is called the troposphere, where all the weather events are. But above that, we have the Stratosphere, a deeper and drier layer and the home of the ozone layer.

For this reason, we tend to separate the entire Polar Vortex into an upper (stratospheric) and a lower (tropospheric) part. They both play their role differently, so we monitor them separately. But it is also very important if they are properly connected—image by NOAA-Climate.

The current Stratospheric Warming event was caused by strong Rossby waves in the first half of the month. Below you can see strong pairings of high and low-pressure regions around ten days ago. This setup enabled the “wave breaking,” sending energy upwards into the Stratosphere and disrupting the Polar Vortex dynamics.


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