Winter is upon us. While some people are excited about ice skating, sledding, and snowmen, some are already wishing for warmer weather. However, a natural phenomenon called the polar vortex indicates that the United States may be facing an extra blast of cold at the end of season. Not only that, but the vortex may bring in the chill in a matter of weeks.
What is a polar vortex?
The polar vortex, also known as the circumpolar vortex, is a massive region of rotating cold air that circles around each of the Earth’s poles. Polar vortices impact the weather in distinctly different ways depending on their size, structure, and seasonal cycles. They are constants in nature but they tend to “show up” around September and linger through April or May.
Paul Pastelok, an AccuWeather senior meteorologist and lead U.S. long range forecaster, explains the vortex as a space of low pressure in the atmosphere over the arctic region. “The rotation normally is out of the counter-clockwise direction because it is an area of low pressure,” Pastelok said to Silive. “And so, when the polar vortex strengthens and becomes strong over the pole, typically what happens as a result of that is that most of the cold is captured and concentrated over the polar region.” This draws a west-to-east flow of cool air and mild temperatures to the areas south of it, including the U.S.
When the polar vortex “leaks”
Typically, the polar vortex keeps the icy arctic air contained to the north pole. However, meterorologists monitor it for disruptions that could result in chilly weather seeping into the U.S. Distruptions can come in the form of sweeps of warm air going into the polar vortex. This leads to “bumps” and “grooves” that open the circulation and allow the cold air to escape. “First of all, it would have to kind of come down to the lower levels, and then air masses around it push it and move it around across the globe,” said Pastelok.
When leaks happen, the disruption can turn into a pattern that lasts three or five weeks. “It’s not a short-term event where you get a cold front followed by a cold snap for a couple of days,” Pastelok said.
A cold finale to the winter season?
In other words, a bump to the polar vortex can turn into a cold spell at the end of the winter season. Although it’s extremely hard to predict a disruption like that so far in advance, Pastelok and his colleagues think there is a decent probability when comparing the weather patterns to previous years.
Bear in mind, the vortex doesn’t only impact North America. Disruptions could also lead to cold air sweeping over Europe or Asia, depending on what else is happening in the weather system at the time.
Upcoming jet streams
However, Americans do not need to wait long to potentially see the impact of the polar vortex since meteorologists are already expecting it to come within January. They predict a jet stream will bring in snow storms, frozen precipitation, and frigid temperatures over most of the United States. Some areas may face temperatures about 30 degrees lower than they’re used to. In fact, this could end up being the coldest January since 2011 for the U.S. as a whole,” said Pastelok to AccuWeather last week.
The dip in the jet stream will come in phases and not all at once. “The first large and long-tracking Arctic high pressure area will sink southward across the Plains and impact Texas early next week],” Pastelok said, “This air mass will continue to follow the storm along the Gulf coast, Tennessee Valley and Southeast between January 8–9.”
By the middle of the month, the temperatures may become colder than the recorded averages. In fact, subzero temperatures will come to a number of North Central states.
Safety preparations
Meanwhile, AccuWeather Senior Director of Forecasting Operations Dan DePodwin predicts that this may be the coldest January since 2014. It may cause power grid issues, problems with frozen pipes, water damage in poorly insulated homes, and snow accumulation.
Remember that jet streams coming from the polar vortex can affect weather for weeks, not a day or two. So take some preventative measures such as insulating water lines, walls, and attics. Calk and weather-strip windows and doors, repair roof leaks, and cut away tree branches that might fall on your home during a storm.
Before snowstorms, the CDC recommends getting your vent and furnace system checked by a technician to ensure they are up to scratch. And finally, stock up on warm items like coats and blankets, flashlights and batteries, portable phone chargers, first aid kits, road salt, a shovel, and a windshield scraper.