Polar Vortex News and Forecasts

All the latest news and forecast articles are found below in chronological order.

 

To understand what the polar vortex is, its usually the best to visualize it. In simple terms, it is just a 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. It nicely shows the actual structure of the polar vortex, connecting down to the lower levels, the pressure systems, and the winter weather patterns.

The whole structure extends high into the atmosphere. The lowest level is called the troposphere, where all weather events occur. But above that, we have the Stratosphere, a deeper and drier layer that is home to the ozone layer.

For this reason, we 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.

The upper (stratospheric) part is more circular and symmetrical as it spins higher above the ground, with fewer obstacles in its flow.

But, the lower structure of the polar vortex is much more uneven and regularly disrupted. That is due to the influence of the terrain/mountains and strong pressure systems acting as obstacles.

The whole structure behaves like a very large cyclone, covering the whole north pole down to the mid-latitudes. It is connected through all atmospheric levels, from the ground up, but can have different shapes at different altitudes.

WHY DO WE MONITOR THE POLAR VORTEX?

We must monitor the state of the polar vortex, as it can profoundly impact our daily weather. We mainly separate the state of this circulation into two different modes:

A strong/stable Polar Vortex usually means we have a strong polar circulation and jet stream. This keeps the colder air trapped into the Arctic Circle, creating milder conditions for most of the United States.

In contrast, a weak/disrupted Polar Vortex creates a weak jet stream pattern. As a result, the jet stream has a harder time containing the cold air, which can now escape from the polar regions into the United States. Image by NOAA.

So, if you want a colder and snowier Winter, your best bet is a weak or disrupted polar vortex. It helps to raise pressure over the polar regions, releasing the cold air towards the lower latitudes.

That is usually achieved by increasing the pressure or temperature in the polar Stratosphere. We call such an event a “Sudden Stratospheric Warming”. As the name suggests, it is a rapid temperature increase in the Stratosphere.

But not every disruption event is a major Stratospheric Warming event. Even smaller disruptions can influence the Polar Vortex and the winter weather at the surface.