“Polar vortex” sounds cool. It’s like “bomb cyclone” or “firenado.” It seems like the sort of phenomenon that would be responsible for the record-breaking blast of cold, snow and wintry conditions that reached all the way to the Gulf Coast this week. The polar vortex is a real thing, but it may not be to blame for the extreme chill that rocked normally warmer regions of the country.
Unusual winter storms and frigid temperatures smacked a large region of the US from Texas to Florida. Snowfall and cold triggered flight cancellations and school, business and road closures. The National Weather Service issued its first-ever blizzard warning for some areas around Lake Charles, Louisiana on Jan. 21. Parts of Houston reportedly received snowfall of up to 6 inches.
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NOAA’s Goes-East satellite captured a view of the historic winter storm in the southern US on Jan. 21.
The NWS office for Mobile, Alabama posted an official snowfall measurement of 5.4 inches on Tuesday afternoon, breaking the one-day record of 5 inches set in 1881. Snow was still falling and reached 7.5 inches for the day. The NWS social media team described that total as “insane.” Nearby Pensacola, Florida saw similar snowfall. It’s natural to look north to the cold Arctic for answers as to why the Gulf Coast took a polar bear plunge into such icy weather.
What is the polar vortex?
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The polar vortex can ride with the jet stream and push cold air into the US under certain conditions.
As the name suggests, the polar vortex is associated with our planet’s north and south poles. It’s 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 feel extremely cold air from the Arctic regions at Earth’s surface, it is sometimes associated with the polar vortex,” the NWS said in an explainer.
The polar vortex can be connected to bouts of extreme cold in the US, but the conditions have to be right. The polar vortex can expand and push south with the jet stream – a narrow current of air that flows high up in the atmosphere from west to east. Notably, a polar vortex struck the US in 2019, launching a volley of Star Wars Hoth jokes about the cold.
Did the polar vortex cause the cold?
The Arctic blast that caused Gulf Coast residents to shiver this week wasn’t necessarily an example of the polar vortex going 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. The scientists examined the polar vortex last week prior to the Arctic blast. At the time, Butler and Ciasto spotted some potential stretching of the polar vortex. But there was another factor in play.
“Additionally, a strong ridge of high pressure has been building up simultaneously near Alaska, which can also help force the jet stream to dive down south over the continental US and bring cold Arctic air with it, independent of the polar vortex,” Butler and Ciasto wrote.
A NOAA video showed what the ridge looked like:
The cold Arctic air hanging out over Alaska took a dive down to the south.
“I think the ridging over Alaska is playing a larger role in the cold air outbreak,” Ciasto told CNET. “The stratospheric polar vortex is not as stretched as it was last week so the connection we pointed out in our last post is less relevant now.”
While the Gulf Coast caught a chill, Alaska experienced an area of high pressure and milder temperatures, according to Erica Grow Cei, NWS public affairs specialist and meteorologist.
“This in turn displaces the Arctic air that normally sits over our northernmost state at this time of year, and the Arctic air moves downstream – southeastward – toward the continental US,” Grow Cei told CNET.
The polar vortex can be a powerful source of winter weather, but it’s not the only cause of severe cold and snow in regions better known for warmth and sunshine. The Gulf Coast states are still digging out of the snowdrifts, but at least warmer temperatures are on tap heading into the weekend.
