Key Takeaways
- The polar vortex is expected to bring bitterly cold air to the US twice in January, with the second round potentially being more extreme.
- The polar vortex is a large-scale area of low pressure and cold air that sits over the Earth’s poles and can bring cold air to the US when it weakens or becomes disrupted.
- The first round of cold air is expected to bring temperatures 10-20 degrees below average to Chicago, while New York City can expect temperatures 5-10 degrees below average.
- Snow is expected in the usual spots, such as the Great Lakes and Northern New England, but it’s unclear if the big cities will see significant snowfall.
- The polar vortex stretch will start in western North America and move east, bringing cold air to the North-Central and Northeastern US.
Introduction to the Polar Vortex
The polar vortex, a familiar winter phenomenon, is set to bring bitterly cold air to the US twice in January. According to AEM climatologist Judah Cohen, the first round of cold air will be an "appetizer" for the main course of cold air that will arrive the following week. This second round of cold air has the potential to be more extreme, with Weather Trader meteorologist Ryan Maue noting that it could be a "potentially historic Arctic ‘polar vortex’ blast across North America into the end of January." The polar vortex is not a storm, but rather a large-scale, persistent area of low pressure and extremely cold air that sits high in the atmosphere over the Earth’s poles.
The Polar Vortex and Cold Air
The polar vortex exists year-round, but it strengthens in winter when polar temperatures drop, and weakens in summer. When the vortex is strong, the cold air stays bottled up over the poles. However, when the vortex weakens, stretches, or becomes disrupted, pieces of that cold air can spill southward into the US, Europe, or Asia, producing outbreaks of frigid Arctic air. In January, the polar vortex will stretch, allowing cold air to move into the US. According to Cohen, the first stretch will return below-normal temperatures to the Eastern US, while the second stretch will start in western North America and move east, bringing cold air to the North-Central and Northeastern US.
Impact on Snow and Temperatures
Snow is a major concern during the polar vortex, but it’s difficult to predict where and when it will fall. Cohen notes that the usual spots, such as the Great Lakes and Northern New England, will continue to see snow, but it’s unclear if the big cities will see significant snowfall. AccuWeather meteorologist Alex Sosnowski notes that the large, rounded shape of the jet stream dip will make it difficult for storms in the South to rapidly strengthen along the Atlantic coast and become major snowstorms. Instead, most storms will stay weak, move quickly, and exit out to sea. Temperatures in Chicago are expected to swing from near average to 10-20 degrees below average over the next one to two weeks, while New York City can expect temperatures 5-10 degrees below average.
Regional Temperature Expectations
The polar vortex will have a significant impact on temperatures across the US. In Chicago, temperatures are expected to drop to 10-20 degrees below average, while New York City can expect temperatures 5-10 degrees below average. The average high in Chicago is near 32 degrees Fahrenheit, so temperatures are expected to be in the teens or single digits. In New York City, temperatures will range from near the historical average in the upper 30s to 5-10 degrees below average. These temperature drops will be significant, and residents in these areas should be prepared for cold weather.
Conclusion and Future Outlook
The polar vortex is a significant winter phenomenon that can bring bitterly cold air to the US. With two rounds of cold air expected in January, residents should be prepared for cold temperatures and potential snowfall. While it’s difficult to predict exactly where and when snow will fall, the usual spots, such as the Great Lakes and Northern New England, will likely see significant snowfall. The polar vortex stretch will start in western North America and move east, bringing cold air to the North-Central and Northeastern US. As the polar vortex continues to evolve, it’s essential to stay up to date with the latest forecast to prepare for the cold weather ahead.