Here’s What You Need To Know About The Polar Vortex
Polar vortex has become a buzzword and is usually used throughout the winter when the Northern Hemisphere experiences its coldest months of the year.
While the name for this phenomenon may sound intimidating to some, the polar vortex is actually a completely natural process that meteorologists have studied for quite some time.
“The polar vortex is a basic fixture of the Earth’s atmosphere,” AccuWeather Meteorologist La Troy Thornton said.
As the name implies, the polar vortex phenomenon occurs at the Earth’s poles. The Earth has two poles, north and south, each located on an end of the Earth’s axis, the planet’s “spine.”
“The polar vortex is defined as a mass of cold air that is tightly bound to polar regions by strong counterclockwise winds known as the polar jet stream,” Thornton explained.
The polar vortex that most often makes headlines in the Northern Hemisphere is associated with the North Pole.
When the polar vortex is strong, the polar jet stream locks bitterly cold, dry air in place over the Arctic. When strong, these winds essentially act as an unscalable wall that frigid air cannot breach.
However, parts of this “wall of wind” can become vulnerable when certain atmospheric conditions build into place. Typically, it will take a large, strong area of high pressure near the Arctic to disturb the polar vortex.
Strong high pressure that develops in the atmosphere surrounding the North Pole can “squish” the polar vortex farther south, into places like North America or Europe and Asia, according to AccuWeather Senior Meteorologist Brett Anderson.
“Think of the strengthening high-pressure area over the polar region as an expanding balloon and a pocket of air outside the balloon as the polar vortex,” Anderson said. “As the balloon fills up with air the pocket of air outside of the balloon — the polar vortex — gets pushed farther away, and in this case, it is being pushed farther south into the mid-latitudes.”
When the polar vortex loses its strength due to strong high pressure that unsettles the jet stream level of the atmosphere, it allows bursts of frigid air to slip past its defenses. It is at this point that its effects can be felt thousands of miles away from the Arctic.
So, while a strong polar vortex may sound more daunting, it is actually a weaker polar vortex that leads to more issues.
“It can seem counterintuitive, but when the flow weakens, pieces of polar air can travel southward and create pools of bitterly cold air that often lead to uncomfortable and stormy results,” AccuWeather Meteorologist and Podcaster Dean DeVore said.
In North America, these areas of frigid, polar air usually impact Canada and portions of the northern tier of the United States. These pushes of air are often referred to as “Arctic outbreaks” due to the fact that the cold air originates in, and “breaks out” of, the Arctic.
During an Arctic outbreak, the polar vortex is able to deliver subzero temperatures to the affected areas of Canada and the United States for several days at a time. It is during these outbreaks of bone-chilling air that temperature records have a greater chance of being challenged.
Although the polar vortex is known for ushering in unseasonable cold to areas outside of the Arctic, not all cold spells in the winter months are driven by the phenomenon.
“In general, only the most bitterly cold stretches are due to the displacement of the polar vortex from its Arctic home,” Thornton explained.
On rare occasions, bitter air ejected from the polar vortex can travel farther south and dip into locations largely unaccustomed to shocking cold. When this does happen, it can create dangerous, even deadly issues.
One such event unfolded in February 2021 when a stretched polar vortex event coincided with a powerful storm. This storm impacted a large swath of the United States and unleashed particularly harrowing effects across the South.
Texas was one of the hardest-hit areas, as the normally temperate state was bombarded with heavy snow, sheets of ice and brutally cold air. This storm was able to tap into an abundance of Arctic air which sent locations that normally encounter high temperatures in the low 60s Fahrenheit, like Dallas, into the teens and single digits.
Snow and ice from the storm overwhelmed entire energy infrastructures across the state and left millions without power in some of the coldest conditions they’ll ever encounter. AccuWeather estimates that the storm and subsequent cold blast led to about $155 billion in damages and economic losses, with $130 billion attributed to Texas alone. More than 200 people were killed.
It was an event made worse by the presence of Arctic air ejected from the polar vortex that residents of the region, and even many across the rest of the country, may not soon forget.
Produced in association with AccuWeather.