Why the U. S. Might Face a Colder, Snowier Winter

Why? The Polar Vortex is Acting Up

The polar vortex, a massive ring of winds in the atmosphere, usually keeps cold air locked near the North Pole. However, when it weakens or gets disturbed, that cold air can spill out and head south.

Two Polar Vortices

1. Tropospheric Vortex: Affects winter weather every year.
2. Stratospheric Vortex: Holds even colder air but doesn't usually impact surface weather.

When the polar vortex is strong, the cold air stays put. But when it's weak, the cold air can escape and head towards the U.S.

Causes of Disruptions

Scientists are still figuring out why these disruptions happen. Possible causes include:

• Stretching of the Vortex: Causes quick cold snaps.
• Sudden Stratospheric Warming (SSW): Leads to bigger disruptions.

These events can take weeks to unfold and can lead to colder temperatures and more snow.

Uncertain Outcomes

An SSW might not happen, and the polar vortex might just stretch out, causing a noticeable change in weather. Other factors, like La Niña, will also play a role in the winter forecast. La Niña can influence weather patterns and increase the chance of a colder December.

Long-Range Forecasts

Long-range forecasts suggest below-average temperatures for most of the U.S. from late November into December. However, these forecasts don't account for short-term variations. So, there could be a cold snap followed by warmer weather, with the average temperature leveling out.

Increased Chances of Snow

These disturbances can also increase the chances of snow. The pattern change supports more winter-like conditions across the central U.S. and increases the potential for heavy snow, especially along the Great Lakes.