“Rising Frequency of Prolonged Cold Snaps: How Shifts in the Jet Stream Are Locking in Extreme Winter Weather”

A new investigation reveals a surge in the occurrence of prolonged and severe winter weather in North America and Europe, often leading to devastating consequences. While global temperatures are on the rise, shifts in the atmosphere are triggering extended periods of extreme cold and wet conditions, defying the overall warming trend.

This study, published in the Bulletin of the American Meteorological Society, uncovers a connection between these harsh weather patterns and significant alterations in the global jet stream. These alterations have resulted in polar air descending further south, causing frigid temperatures and persistent precipitation across vast regions of North America and Europe. Notably, these extreme weather waves have doubled in frequency since the 1960s, causing disruptions in daily life and infrastructure.

Understanding the Jet Stream and Its Anomalies

The jet stream, a high-speed air current circling the Northern Hemisphere, typically follows a relatively straight path, separating cold polar air from the milder midlatitudes. However, it can occasionally develop large undulations or “wobbles.” Some scientists attribute the increasing size and frequency of these wobbles to rapid Arctic warming, which destabilizes the system, generating winds that disrupt the north-south boundary. Under certain conditions, these wobbles can amplify into symmetrical waves known as Rossby waves.

Rossby Waves and Their Impact on Weather

Previous research in 2019 by Kai Kornhuber and colleagues identified a recurring Rossby wave pattern called “wave-7,” characterized by seven peaks and seven troughs across the globe. This pattern draws warm, dry air from subtropical regions into the midlatitudes, causing simultaneous summer heatwaves and droughts across North America, Europe, and Asia, leading to significant crop losses.

This recent study, however, explores the opposite effect. It focuses on the “wave-4” winter pattern, featuring four peaks and four troughs that tend to become stationary. In the presence of this pattern, the likelihood of extreme cold or wet conditions in the troughs significantly increases. Conversely, abnormally warm or dry conditions may develop in the peaks.

Real-world Consequences

One prominent example of a major wave-4 pattern was the February 2021 cold wave that swept across Canada, the United States, and northern Mexico. Temperatures plummeted to 50 degrees Fahrenheit below average, even reaching the U.S. Gulf Coast. This event resulted in widespread disruption, including natural gas pipeline failures, power grid outages, and significant economic losses. At least 278 people lost their lives, and the damage exceeded $200 billion. A similar but less severe event occurred in January-February 2019 in the eastern United States, claiming more than 20 lives.

Synchronized Weather Events

Interestingly, these extreme weather patterns often affect both sides of the Atlantic simultaneously, with southwestern Europe and Scandinavia experiencing the most severe impacts. For instance, the January-February 2019 event brought extreme cold to southern France and Sweden while causing widespread precipitation and flooding in central and eastern Europe.

The Frequency of Concurrent Waves

The research reveals that concurrent wave patterns, which used to occur once per winter on average 50 years ago, now happen twice a year, on average. This suggests a growing synchronization of extreme weather events over North America and Europe.

Future Research and Implications

The exact mechanisms behind the emergence of wave-4 patterns require further investigation. While climate change’s role in amplifying summer heatwaves is increasingly understood, its connection to winter weather patterns remains a topic of intense scientific debate. Scientists are exploring various potential mechanisms to better predict these extreme cold and wet waves and to determine whether they are driven by human-induced climate change or natural variability.

In conclusion, the study underscores the complex relationship between climate change, atmospheric dynamics, and the frequency of extreme weather events. Understanding these patterns is crucial for preparing and mitigating the impacts of such weather extremes in the future.

Frequently Asked Questions (FAQs) about Winter Weather Patterns

More about Winter Weather Patterns

• Bulletin of the American Meteorological Society
• Columbia University’s Lamont-Doherty Earth Observatory
• Kai Kornhuber’s Research
• Rossby Waves and Weather Anomalies
• Arctic Warming and Its Impact
• Jet Stream and Climate Change
• Extreme Weather Events
• Synchronized Weather Events