“Polar vortex” sounds nice. It’s like “bomb cyclone” or “firenado”. It looks like the kind of phenomenon that would be responsible for the record-breaking blast of cold, snowy and wintry conditions that reached the Gulf Coast this week. The polar vortex is a real thing, but it may not be to blame for the extreme cold that rocked normally warmer regions of the country.
Unusual winter storms and cold temperatures battered a large region of the US from Texas to Florida. The snow and cold caused the cancellation of flights and the closure of schools, businesses and roads. The National Weather Service issued its first-ever thunderstorm warning for several areas around Lake Charles, Louisiana on January 21. Parts of Houston reportedly received up to 6 inches of snowfall.
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NOAA’s Goes-East satellite captured a view of the historic winter storm in the southern US on January 21.
The NWS office for Mobile, Alabama posted an official snowfall measurement of 5.4 inches Tuesday afternoon, breaking the one-day record of 5 inches set in 1881. Snow was still falling and totaled 7.5 inches for the day. The NWS social media team described that total as “crazy.” Near Pensacola, Florida saw similar snowfall. It’s only natural to look north to the frigid Arctic for answers as to why the Gulf Coast drowned a polar bear in such icy weather.
What is the polar vortex?
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The polar vortex can cross the jet stream and push cold air into the US under certain conditions.
As the name suggests, the polar vortex is connected to the north and south poles of our planet. It is an area of lower pressure and cold air at each pole.
Weather forecasters examine the polar vortex by looking at conditions tens of thousands of feet up in the atmosphere; however, when we experience extremely cold air from the Arctic regions at Earth’s surface, it is sometimes associated with the polar vortex,” the NWS said in an explanation.
The polar vortex can be associated with periods of extreme cold in the US, but conditions have to be right. The polar vortex can expand and push south with the jet stream – a narrow stream of air that flows up in the atmosphere from west to east. Notably, a polar vortex hit the US in 2019, setting off a flurry of Star Wars Hoth jokes about the cold.
Did the polar vortex cause the cold?
The Arctic blast that sent Gulf Coast residents shivering this week wasn’t necessarily an example of the polar vortex on the attack.
Amy Butler and Laura Ciasto with the National Oceanic and Atmospheric Administration run a polar vortex blog on NOAA’s Climate.gov site. Scientists examined the polar vortex last week ahead of the Arctic blast. At that time, Butler and Ciasto observed a possible extension of the polar vortex. But there was another factor at play.
“Additionally, a strong ridge of high pressure has simultaneously formed near Alaska, which may also help force the jet stream to dip south over the continental US and bring cold Arctic air with it, regardless of polar vortex,” Butler and Ciasto wrote.
A NOAA video showed what the ridge looked like:
The cold Arctic air that hung over Alaska plunged south.
“I think the passage over Alaska is playing a bigger role in the cold air burst,” Ciasto told CNET. “The stratospheric polar vortex is not as extensive as it was last week, so the link we highlighted in our last post is less relevant now.”
While the Gulf Coast caught a cold snap, Alaska experienced an area of high pressure and milder temperatures, according to Erica Grow Cei, NWS public affairs specialist and meteorologist.
“That in turn shifts the Arctic air that normally sits over our northernmost state at this time of year, and the Arctic air moves downstream — southeast — toward the continental U.S.,” Grow Cei told CNET.
The polar vortex can be a powerful source of winter weather, but it’s not the only cause of bitter cold and snow in regions better known for warmth and sunshine. The Gulf Coast states are still reeling from snowfall, but at least warmer temperatures are on the way into the weekend.