A final Polar Vortex collapse event is forecast for mid-March. With a very strong stratospheric warming event expected to develop, we currently see a rapid breakdown of the Polar Vortex. The event is still several days ahead, with impacts following further behind, but we do already see first hints of impacts across the United States and Canada.
This is now the second disruption of the Polar Vortex in 2025. The first occurred around mid-February and coincided with a strong cold air release across much of the central and eastern United States.
This upcoming event in the stratosphere looks stronger than the first one and is forecast to be the final collapse of the Polar Vortex for this season. That would mean we won’t get to see the Polar Vortex in the stratosphere until the next 2025/2026 Winter season.
WEATHER UNDER THE POLAR VORTEX
The best way to understand the Polar Vortex is to see its structure. But in simple terms, it is just a name that describes the broad winter circulation over the northern (and southern) hemispheres.
Below is a 3D image example of the Polar Vortex. The vertical scale is greatly enhanced for better visual presentation. You can see the actual structure of the Polar Vortex, connecting from the stratosphere down to the lower levels and the pressure systems.
The Polar Vortex extends high across different layers of 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.
For this reason, we separate the Polar Vortex into an upper (stratospheric) and a lower (tropospheric) part. They both play their roles differently, so we have to monitor them separately. However, both parts together form the circulation across the Northern Hemisphere during the colder part of the year (October-March).
To keep things simple, all you need to know is that the upper and lower parts of the Polar Vortex are connected. Changes in the upper part can significantly impact the weather anomalies in the lower parts of the atmosphere and the weather at the surface.
The reason we monitor the state of the Polar Vortex is that it can have a profound impact on our daily weather. We mainly separate the Polar Vortex into two different modes:
A strong/stable Polar Vortex usually means strong polar circulation and a strong jet stream. This locks the colder air into the Arctic Circle, creating milder conditions for most of the United States and warmer-than-normal conditions over southern Canada.
In contrast, a weak/disrupted Polar Vortex creates a weak jet stream pattern. As a result, it has a harder time containing the cold air, which can now escape from the polar regions into the United States and Canada. Image by NOAA.
For example, a weak Polar Vortex can greatly increase the odds of cold and snow across the central or eastern United States. In nature, that means a heavy disruption of the jet stream and a release of cold air from the polar regions.
To put the Polar Vortex into perspective, we produced a high-resolution video below showing it in 3D. This gives you a better idea of what it actually looks like in nature. But keep in mind that the vertical size of the vortex was greatly enhanced for visual purposes.
The main takeaway from the video should be that the Polar Vortex is the entire weather circulation over the Northern Hemisphere and not just one cold/storm event over the Midwest or the northeastern United States.
POLAR VORTEX LAST STAND
The stratospheric Polar Vortex is currently larger in size. It is slightly displaced towards the eastern hemisphere and compressed, showing an oval shape. You can see a high-pressure region forming in the stratosphere, which is pushing against the Polar Vortex and creating its deformed shape.
The image above shows geopotential height and temperature in the mid-stratosphere at 30km/18.5miles height. The Polar Vortex resembles a “cyclone” with a cold core near its low-pressure center.
Below is the latest image of the Polar Vortex in the lower Stratosphere at the 50mb pressure level (20km/12.5miles). You can see how the Polar Vortex is also elongated in the lower stratosphere, pressed from the Pacific side. The Polar Vortex at this level shows a rather weak core, split into two smaller central regions.
Looking at the current structure of the Polar Vortex in 3D, we can better see its elongated or oval structure. It is otherwise fairly stable in place with altitude, keeping in one spot with not much tilt to its whole structure. Image by stratobserve.
The Polar Vortex might currently still be in good condition, but the latest stratospheric forecast shows a very intense upcoming disruption. In the image below, you can see the ensemble forecast for wind and temperature in the mid-stratosphere. A strong warming wave can be seen on the temperature graph, raising stratospheric temperatures far beyond normal values.
The wind forecast shows negative values in the stratosphere, meaning the circulation will reverse from the usual westerly to easterly. This also meets the official criteria for this event to be a major Sudden Stratospheric Warming event (SSW).
Winds are the first indicator that the Polar Vortex is expected to lose power. To determine its power, we tend to measure how strong the winds are around the polar circle in the stratosphere. If those winds get weak or reverse from west to east, it signals a potentially strong disruption from the stratosphere down to the lower levels and our weather.
The Polar Vortex is always very cold when it is in good condition. When temperatures rise, it shows that something will happen to the Polar Vortex. So, when we see temperatures rising fast and wind speeds dropping, it is a strong statement that the Polar Vortex will weaken or even collapse.
THE POLAR VORTEX COLLAPSE BEGINS
Below is the mid-stratospheric forecast 8 days from now for late next week. It shows the stratospheric high-pressure system to grow very large and push against the Polar Vortex. This completely changes the wind dynamics in the stratosphere, and you can also see a very strong warming wave between the systems. This is almost like sparks flying when the two large systems collide in the stratosphere.
This substantially reduces the westerly wind speed in the stratosphere and sends a strong disruption wave downwards. Imagine having a large stack of plates, and as the whole stack starts to wobble around, it can even start collapsing from above, eventually bringing down the whole stack.
The forecast below is for mid-March, and it shows the high-pressure area growing further, taking over the polar regions, and splitting apart the Polar Vortex. One core will move into Eurasia, and one will move into North America. This is still shown at the 10mb level (31km/18.5miles), but the pressure anomalies in the lower levels tend to follow the upper dynamics with some delay.
Below is the pressure anomaly forecast for the mid-levels of the stratosphere at 10mb (30km/18.5miles). You can see a strong high-pressure anomaly over the pole and two low-pressure areas, one pushed into the eastern hemisphere, and one core is left over North America. This indicates a rapid response across the entire depth of the stratosphere.
Looking further below at the 50m level in the lower stratosphere, we can see the split Polar Vortex all the way down through the whole stratosphere. You can also see the strong warming wave reaching all the way down, which is impressive to see with this magnitude. You can also see the core over North America reaching almost into the United States.
So, to recap, the Polar Vortex is about to undergo a major shift in the stratosphere and very likely its total collapse. Depending on the timing, a weak Polar Vortex can substantially change the weather patterns across the United States and the rest of the Northern Hemisphere.
The 3D vertical structure forecast below shows the deformed and split shape of the Polar Vortex around mid-month. It is no longer seen as circular or compact. It is getting torn apart, completely changing its dynamics and weather impacts, as the high-pressure area creates a “void” seen in the structure of the Polar Vortex.
Below is the extended wind forecast for the Polar Vortex. You can see the forecast average going negative around mid-March. This means a true wind reversal in the stratosphere, signaling a major collapse of the Polar Vortex.
We can also look at the forecast graphic for the winds across the atmosphere. In the left part of the graphic, you can see strong reversed winds in the stratosphere starting later next week. In the right part, you can see the anomalies, where it is easier to see how this wind anomaly translates towards the surface levels. Image by weatheriscool.com
The stratospheric warming event is still a few days away, but a full wind reversal is starting to look increasingly likely as different forecasting systems see it. We will now look at what we usually expect from such events and the latest forecast for the weather development during that period.
WEATHER FROM ABOVE
Sudden Stratospheric Warming basically means a strong temperature and pressure rise in the Stratosphere. That causes a major disturbance in the circulation and, as a result, starts a collapse of the Polar Vortex. But how does it actually change the weather?
Below is a typical example of how a stratospheric warming event works. The image below shows pressure anomalies across the atmosphere over the whole period of an SSW event. You can see how the main event in the stratosphere slowly affects the surface layers below over a certain time period.
An SSW event usually means high-pressure anomalies from the stratosphere making their way to the surface. This disrupts the jet stream, helping to unlock cold air from the polar regions down into the United States and the rest of the mid-latitudes.
We can first look at the temperature anomalies over the polar regions by altitude. You can see the strong temperature anomaly in the stratosphere, seen in the forecast part of the image. That is the stratospheric warming wave, making its way down across the stratospheric layer.
We also have to look at the pressure anomalies. You can see a high-pressure anomaly marked in the forecast part of the graphic. It shows the high-pressure anomaly developing in the stratosphere, and it is starting to make its way down as we go into mid-March. But as you can see, the high-pressure anomaly form the SSW is not yet fully connected down in the forecast.
That usually means a weakened jet stream and low-pressure systems over North America in this event. In normal conditions, this would help unlock a new round of cold air from the Arctic, sending it down into the mid-latitudes.
Below is the updated pressure pattern forecast for mid-month. You can see a broad low-pressure area over Canada. This low-pressure area is connected to the remaining core of the Polar Vortex that is above North America in the stratosphere.
You can also see that the low-pressure area extends into the United States. The temperature outcome depends on how this low-pressure area is positioned. This is not necessarily a sole direct result of the stratospheric dynamics. But, the whole system is connected and reflects changes from above to below and vice versa.
Below is the temperature forecast for the same period. It shows a mass of cold air gathering in western Canada and the western United States. At the same time, a warm wave is just moving out of the eastern United States. This forecast range is just starting to reach into the post-SSW period, so for now, we do see an accumulation of cold air, which is phase 1.
If we look at the GFS model from the U.S. NCEP center, it shows a similar example. Cold air is gathering over southern Canada and the western United States. Because the low-pressure arm over the United States is further west, that brings warmer air up into the central and eastern United States.
But because these forecasts do not reach further into the period, we can only see the beginning of the SSW aftermath in the current forecasts.
We will keep you updated on the global weather pattern development, so bookmark our page. Also, if you have seen this article in the Google App (Discover) feed, click the like button (♥) there to see more of our forecasts and our latest articles on weather and nature in general.
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