Polar Vortex Disruption: What to Expect This December

High above the North Pole, a dramatic transformation is underway in the stratosphere. This November, scientists are witnessing an almost unprecedented polar vortex disruption that could set the stage for a cold, snowy December across the Northern Hemisphere.

Understanding the Polar Vortex

Think of the stratospheric polar vortex as a wall of wind that corrals the ultra-cold, Arctic air over the North Pole. When this polar vortex weakens, cold air can spill south into regions like the Lower 48 states, Europe, and Asia, bringing frigid temperatures and potentially disruptive weather patterns.

The Current Disruption: A Rare November Event

What makes this event particularly noteworthy is its timing. According to meteorologist Judah Cohen of MIT, sudden stratospheric warming events of this magnitude are almost unheard of in November. Currently, the air in the stratosphere—the layer of atmosphere above where most weather occurs—is warming quickly and dramatically in a phenomenon known as a sudden stratospheric warming event.

"The sudden warming in the far upper atmosphere is going to result in anything but warmth. It is causing the polar vortex winds to weaken, and they could even reverse."
— Amy H. Butler, meteorologist at NOAA

Weather Impacts Across the Hemisphere

Over the next two weeks, these shifts are expected to be felt across North America, Europe, and Asia as the polar vortex weakens and potentially tumbles south. Meteorologists compare it to a spinning top that slows down and wobbles off course.

For regions of the US currently experiencing record heat, this disruption means a dramatic swing in weather could begin as early as the week of Thanksgiving. While scientists caution that a major winter blast isn't guaranteed, they are watching for colder than normal conditions to develop in the mid-latitudes—where most of the world's population resides—over the next month.

The Science Behind the Pattern

Once the polar vortex is disrupted, it can take a month or more to recover, according to Andrea Lopez Lang, a meteorologist at the University of Wisconsin-Madison. These events tend to generate a ridge of warm, high pressure over Alaska, which in turn triggers a dip, or trough, in the jet stream to the east. This trough can usher in colder, snowier weather over the Central states and portions of the Eastern US.

"We can see more active and shifted storm tracks and increases in cold air outbreaks in regions across the Northern Hemisphere," Lopez Lang explained.

Monitoring Challenges

Despite the significant impacts of these polar vortex events, scientists are facing challenges in monitoring the stratosphere. Satellites are crucial for observing this layer of the atmosphere and making predictions about sudden stratospheric warming events, but some data is becoming unavailable as satellites age and NOAA makes budget decisions affecting measurement programs.

"The only way that we really observe these phenomena is via satellite data."
— Andrea Lopez Lang, University of Wisconsin-Madison

What to Watch For

As we head into December, meteorologists will be closely watching how this polar vortex disruption unfolds. While there's still uncertainty about exactly where the icy blast will hit, the pattern suggests an increased likelihood of colder and snowier conditions in parts of the US and other Northern Hemisphere regions.

Even though the stratospheric polar vortex is miles above us, it's sometimes connected to our weather via invisible puppet strings described by atmospheric dynamics and thermodynamics. Understanding these connections can help improve 7- to 10-day forecasts, providing valuable information for planning and decision-making.

Whether you're preparing for holiday travel or just curious about winter weather patterns, this rare November polar vortex disruption is worth watching as it could shape the weather we experience throughout December.