A major atmospheric event is on the horizon. Forecasts predict that the Polar Vortex will undergo a final collapse in mid-March due to a strong stratospheric warming event. This breakdown is expected to influence weather patterns across North America in the coming weeks.
What’s Happening with the Polar Vortex?
This will be the second disruption of the Polar Vortex in 2025. The first occurred in mid-February, leading to a strong cold air outbreak across the central and eastern United States. However, this upcoming event is expected to be even more intense, marking the final collapse of the Polar Vortex for this winter season. Once it weakens, we won’t see its return until the next winter season of 2025/2026.
Understanding the Polar Vortex
The Polar Vortex is a large-scale weather system that circulates over the Northern Hemisphere during the colder months. It exists in two parts:
- The upper part in the stratosphere (above where most weather occurs), and
- The lower part in the troposphere (where weather systems form).
These two layers are interconnected, meaning changes in the stratosphere can have significant effects on surface weather.
- A strong and stable Polar Vortex keeps the cold air trapped in the Arctic, leading to milder winter conditions for much of the U.S. and Canada.
- A weak or disrupted Polar Vortex allows Arctic air to escape, causing sudden cold snaps and snowstorms across the mid-latitudes.
The Current State of the Polar Vortex
Right now, the stratospheric Polar Vortex is larger than usual but slightly displaced, taking on an elongated, oval shape. A high-pressure system is pushing against it, causing deformation and weakening its structure.
Forecast models indicate that a powerful warming event in the stratosphere will soon cause a complete breakdown of the vortex. As temperatures rise and wind speeds drop, the system will weaken significantly and likely collapse altogether. This would be a game-changer for weather patterns across the Northern Hemisphere.
How Will This Impact Weather in North America?
Once the Polar Vortex collapses, the effects on North America’s weather could be significant.
- Increased likelihood of cold outbreaks: A disrupted Polar Vortex can lead to cold air surges from the Arctic, bringing frigid temperatures and snowstorms to parts of the U.S. and Canada.
- Changes in storm patterns: The jet stream, which controls storm movement, will likely become unstable, increasing the chances of extreme weather events.
- Longer-lasting effects: While the collapse is expected in mid-March, its influence on weather could persist for weeks as the atmosphere adjusts.
What the Forecast Shows
Models predict that by mid-March, the high-pressure system will grow stronger, splitting the Polar Vortex into two separate cores—one shifting toward Eurasia and the other over North America. This will result in a significant shift in weather patterns:
- A low-pressure system will likely develop over Canada, extending into the United States.
- Cold air will build up over western Canada and the western U.S., while the eastern U.S. may experience a brief warm spell before temperatures drop.
- The jet stream will weaken and become unstable, increasing the chances of cold air intrusions into the U.S. and heavier snowfall in some areas.
What’s Next?
A sudden stratospheric warming (SSW) event, like the one forecasted, can take time to fully influence surface weather. While the collapse of the Polar Vortex is expected in mid-March, its impact on weather may not be fully realized until late March or even early April.
As the event unfolds, we will closely monitor weather patterns and provide updates on how this final collapse of the Polar Vortex will shape the rest of the season. Stay tuned for more forecasts and insights on how these atmospheric changes will impact daily weather across North America.
