Early Polar Vortex Event Could Trigger Record Cold December

High above the North Pole, in a slice of atmosphere rarely noticed by the average person, a dramatic transformation is underway. Over the next 10 days, changes in the stratosphere will upend weather patterns and potentially set the stage for a cold, snowy December across parts of the Northern Hemisphere.

This rare event involves the polar vortex—a phenomenon that's about to bring a wild weather pattern change to regions currently experiencing unseasonable warmth. What exactly is happening, and should you prepare for an early winter blast?

Understanding the Polar Vortex

Think of the stratospheric polar vortex like a wall of wind, corralling the ultra-cold, Arctic air over the North Pole. When this polar vortex weakens, cold air spills south into places like the continental United States, Europe, and Asia.

Currently, the air in the stratosphere—the layer of the atmosphere above where most weather occurs—is warming quickly and dramatically in a phenomenon known as a sudden stratospheric warming event. This warming event is causing the polar vortex winds to weaken, and they could even reverse direction.

Why This Event Is Unusual

"Sudden stratospheric warming events of this magnitude are almost unheard of in November," said meteorologist Judah Cohen, a research scientist at MIT. This timing makes the current event particularly noteworthy and difficult to predict.

Scientists are still working to understand why these warming events happen. For now, what's clear is that they can trigger the most intense polar vortex cold-air outbreaks in the US and other regions. The current event is significant enough that it could be one of the earliest major polar vortex disruptions recorded since the dawn of the satellite era.

What This Means for Weather Patterns

Over the next two weeks, these shifts will likely begin to be felt across the Northern Hemisphere. As the polar vortex weakens and tumbles south—like a spinning top that slows and wobbles off course—weather patterns will shift dramatically.

"We can see more active and shifted storm tracks and increases in cold air outbreaks in regions across the Northern Hemisphere," explained Andrea Lopez Lang, a meteorologist at the University of Wisconsin-Madison.

Historically, polar vortex events like these tend to generate a ridge of warm, high pressure over Alaska, which 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.

What to Expect in December

While it's not certain there will be a major winter blast, scientists 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 or so.

"Once the polar vortex is disrupted, it can take a month or more to recover," Lopez Lang noted. This means the effects could persist well into December.

What's most difficult to predict is where the polar vortex will deliver its icy blast. Current temperature outlooks aren't fully accounting for this event yet.

The Science Behind the Event

Other polar vortex events early in the winter have been followed by colder and snowier Decembers in the US, providing a pattern that scientists are watching closely.

Challenges in Tracking These Events

As impactful as these polar vortex events are, scientists face challenges monitoring this layer of the atmosphere. "Satellites are crucial to observing the stratosphere and making predictions about sudden stratospheric warming events," Lopez Lang emphasized.

Unfortunately, some satellite data is becoming unavailable as satellites age and NOAA makes budget and program decisions that affect measurement capabilities. "The only way that we really observe these phenomena is via satellite data," she said, citing newly missing data from polar-orbiting satellites as an example.

What You Should Know

While scientists continue to monitor this developing situation, there are a few key takeaways:

• This could be one of the earliest significant polar vortex disruptions on record
• Colder and potentially snowier conditions may develop across parts of the Northern Hemisphere
• The effects could persist for weeks or even months
• Forecast accuracy may improve as meteorologists incorporate this stratospheric data

As we head into December, stay tuned to weather forecasts and prepare for potentially changing conditions. The polar vortex, though high above us, may soon be making its presence felt quite dramatically on the ground.