How the polar vortex and warm ocean intensified a major US winter storm

Mathew Barlow, UMass Lowell and Judah Cohen, Massachusetts Institute of Technology (MIT)

A severe winter storm that brought crippling freezing rain, sleet and snow to a large part of the U.S. in late January 2026 left a mess in states from New Mexico to New England. Hundreds of thousands of people lost power across the South as ice pulled down tree branches and power lines, more than a foot of snow fell in parts of the Midwest and Northeast, and many states faced bitter cold that was expected to linger for days.

The sudden blast may have come as a shock to many Americans after a mostly mild start to winter, but that warmth may have partly contributed to the ferocity of the storm.

As atmospheric and climate scientists, we conduct research that aims to improve understanding of extreme weather, including what makes it more or less likely to occur and how climate change might or might not play a role.

To understand what Americans are experiencing with this winter blast, we need to look more than 20 miles above the surface of Earth, to the stratospheric polar vortex.

What creates a severe winter storm like this?

Multiple weather factors have to come together to produce such a large and severe storm.

Winter storms typically develop where there are sharp temperature contrasts near the surface and a southward dip in the jet stream, the narrow band of fast-moving air that steers weather systems. If there is a substantial source of moisture, the storms can produce heavy rain or snow.

In late January, a strong Arctic air mass from the north was creating the temperature contrast with warmer air from the south. Multiple disturbances within the jet stream were acting together to create favorable conditions for precipitation, and the storm system was able to pull moisture from the very warm Gulf of Mexico.

Where does the polar vortex come in?

The fastest winds of the jet stream occur just below the top of the troposphere, which is the lowest level of the atmosphere and ends about seven miles above Earth’s surface. Weather systems are capped at the top of the troposphere, because the atmosphere above it becomes very stable.

The stratosphere is the next layer up, from about seven miles to about 30 miles. While the stratosphere extends high above weather systems, it can still interact with them through atmospheric waves that move up and down in the atmosphere. These waves are similar to the waves in the jet stream that cause it to dip southward, but they move vertically instead of horizontally.

You’ve probably heard the term “polar vortex” used when an area of cold Arctic air moves far enough southward to influence the United States. That term describes air circulating around the pole, but it can refer to two different circulations, one in the troposphere and one in the stratosphere.

The Northern Hemisphere stratospheric polar vortex is a belt of fast-moving air circulating around the North Pole. It is like a second jet stream, high above the one you may be familiar with from weather graphics, and usually less wavy and closer to the pole.

Sometimes the stratospheric polar vortex can stretch southward over the United States. When that happens, it creates ideal conditions for the up-and-down movement of waves that connect the stratosphere with severe winter weather at the surface.

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The forecast for the January storm showed a close overlap between the southward stretch of the stratospheric polar vortex and the jet stream over the U.S., indicating perfect conditions for cold and snow.

The biggest swings in the jet stream are associated with the most energy. Under the right conditions, that energy can bounce off the polar vortex back down into the troposphere, exaggerating the north-south swings of the jet stream across North America and making severe winter weather more likely.

This is what was happening in late January 2026 in the central and eastern U.S.

If the climate is warming, why are we still getting severe winter storms?

Earth is unequivocally warming as human activities release greenhouse gas emissions that trap heat in the atmosphere, and snow amounts are decreasing overall. But that does not mean severe winter weather will never happen again.

Some research suggests that even in a warming environment, cold events, while occurring less frequently, may still remain relatively severe in some locations.

One factor may be increasing disruptions to the stratospheric polar vortex, which appear to be linked to the rapid warming of the Arctic with climate change.

Additionally, a warmer ocean leads to more evaporation, and because a warmer atmosphere can hold more moisture, that means more moisture is available for storms. The process of moisture condensing into rain or snow produces energy for storms as well. However, warming can also reduce the strength of storms by reducing temperature contrasts.

The opposing effects make it complicated to assess the potential change to average storm strength. However, intense events do not necessarily change in the same way as average events. On balance, it appears that the most intense winter storms may be becoming more intense.

A warmer environment also increases the likelihood that precipitation that would have fallen as snow in previous winters may now be more likely to fall as sleet and freezing rain.

There are still many questions

Scientists are constantly improving the ability to predict and respond to these severe weather events, but there are many questions still to answer.

Much of the data and research in the field relies on a foundation of work by federal employees, including government labs like the National Center for Atmospheric Research, known as NCAR, which has been targeted by the Trump administration for funding cuts. These scientists help develop the crucial models, measuring instruments and data that scientists and forecasters everywhere depend on.

This article, originally published Jan. 24, 2026, has been updated with details from the weekend storm.

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Mathew Barlow, Professor of Climate Science, UMass Lowell and Judah Cohen, Climate scientist, Massachusetts Institute of Technology (MIT)

This article is republished from The Conversation under a Creative Commons license. Read the original article.

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Geoff Childs, Washington University in St. Louis

Dorje Dundul recently had his foot gnawed by a brown bear – a member of the species Ursus thibetanus, to be precise.

It wasn’t his first such encounter. Recounting the first of three such violent experiences over the past five years, Dorje told our research team: “My wife came home one evening and reported that a bear had eaten a lot of corn from the maize field behind our house. So, we decided to shoo it away. While my wife was setting up camp, I went to see how much the bear had eaten. The bear was just sitting there; it attacked me.”

Dorje dropped to the ground, but the bear ripped open his shirt and tore at his shoulder. “I started shouting and the bear ran away. My wife came, thinking I was messing with her, but when she saw the wounds, she knew what had happened.”

Researchers Dolma Choekyi Lama, Tsering Tinley and I spoke with Dorje – a 71-year-old resident of Nubri, a Buddhist enclave in the Nepalese highlands – as part of a three-year study of aging and migration.

Now, you may be forgiven for asking what a bear attack on a septuagenarian has to do with demographic change in Nepal. The answer, however, is everything.

In recent years, people across Nepal have witnessed an increase in bear attacks, a phenomenon recorded in news reports and academic studies.

Inhabitants of Nubri are at the forefront of this trend – and one of the main reasons is outmigration. People, especially young people, are leaving for education and employment opportunities elsewhere. It is depleting household labor forces, so much so that over 75% of those who were born in the valley and are now ages 5 to 19 have left and now live outside of Nubri.

It means that many older people, like Dorje and his wife, Tsewang, are left alone in their homes. Two of their daughters live abroad and one is in the capital, Kathmandu. Their only son runs a trekking lodge in another village.

Scarcity of ‘scarebears’

Until recently, when the corn was ripening, parents dispatched young people to the fields to light bonfires and bang pots all night to ward off bears. The lack of young people acting as deterrents, alongside the abandonment of outlying fields, is tempting bears to forage closer to human residences.

Outmigration in Nubri and similar villages is due in large part to a lack of educational and employment opportunities. The problems caused by the removal of younger people have been exacerbated by two other factors driving a rapidly aging population: People are living longer due to improvements in health care and sanitation; and fertility has declined since the early 2000s, from more than six to less than three births per woman.

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These demographic forces have been accelerating population aging for some time, as illustrated by the population pyramid constructed from our 2012 household surveys in Nubri and neighboring Tsum.

A not-so-big surprise, anymore

Nepal is not alone in this phenomenon; similar dynamics are at play elsewhere in Asia. The New York Times reported in November 2025 that bear attacks are on the rise in Japan, too, partly driven by demographic trends. Farms there used to serve as a buffer zone, shielding urban residents from ursine intruders. However, rural depopulation is allowing bears to encroach on more densely populated areas, bringing safety concerns in conflict with conservation efforts.

Dorje can attest to those concerns. When we met him in 2023 he showed us deep claw marks running down his shoulder and arm, and he vowed to refrain from chasing away bears at night.

So in October 2025, Dorje and Tsewang harvested a field before marauding bears could get to it and hauled the corn to their courtyard for safekeeping. The courtyard is surrounded by stone walls piled high with firewood – not a fail-safe barrier but at least a deterrent. They covered the corn with a plastic tarp, and for extra measure Dorje decided to sleep on the veranda.

He described what happened next:

“I woke to a noise that sounded like ‘sharak, sharak.’ I thought it must be a bear rummaging under the plastic. Before I could do anything, the bear came up the stairs. When I shouted, it got frightened, roared and yanked at my mattress. Suddenly my foot was being pulled and I felt pain.”

Dorje suffered deep lacerations to his foot. Trained in traditional Tibetan medicine, he staunched the bleeding using, ironically, a tonic that contained bear liver.

Yet his life was still in danger due to the risk of infection. It took three days and an enormous expense by village standards – equivalent to roughly US$2,000 – before they could charter a helicopter to Kathmandu for further medical attention.

And Dorje is not the only victim. An elderly woman from another village bumped into a bear during a nocturnal excursion to her outhouse. It left her with a horrific slash from forehead to chin – and her son scrambling to find funds for her evacuation and treatment.

So how should Nepal’s highlanders respond to the increase in bear attacks?

Dorje explained that in the past they set lethal traps when bear encroachments became too dangerous. That option vanished with the creation of Manaslu Conservation Area Project, or MCAP, in the 1990s, a federal initiative to manage natural resources that strictly prohibits the killing of wild animals.

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Learning to grin and bear it?

Dorje reasons that if MCAP temporarily relaxed the regulation, villagers could band together to cull the more hostile bears. He informed us that MCAP officials will hear nothing of that option, yet their solutions, such as solar-powered electric fencing, haven’t worked.

Dorje is reflective about the options he faces as young people leave the village, leaving older folk to battle the bears alone.

“At first, I felt that we should kill the bear. But the other side of my heart says, perhaps I did bad deeds in my past life, which is why the bear bit me. The bear came to eat corn, not to attack me. Killing it would just be another sinful act, creating a new cycle of cause and effect. So, why get angry about it?”

It remains to be seen how Nubri’s residents will respond to the mounting threats bears pose to their lives and livelihoods. But one thing is clear: For those who remain behind, the outmigration of younger residents is making the perils more imminent and the solutions more challenging.

Dolma Choekyi Lama and Tsering Tinley made significant contributions to this article. Both are research team members on the author’s project on population in an age of migration.

Geoff Childs, Professor of Sociocultural Anthropology, Washington University in St. Louis

This article is republished from The Conversation under a Creative Commons license. Read the original article.

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John Affleck, Penn State

When I first heard about the arrests of Portland Trail Blazers coach Chauncey Billups, Miami Heat guard Terry Rozier and former NBA player Damon Jones in connection to federal investigations involving illegal gambling, I couldn’t help but think of a recent moment in my sports writing class.

I was showing my students a clip from an NFL game between the Jacksonville Jaguars and Kansas City Chiefs. Near the end of play, Jaguars quarterback Trevor Lawrence threw a perfect pass to receiver Brian Jones Jr. to secure a critical first down. Out of the blue, a student groaned and said that he’d lost US$50 on that throw.

I thought of that moment because it revealed how ubiquitous sports betting has become, how much the types of bets have changed over time, and – given these trends – how it’s naive to think players won’t continue to be tempted to game the system.

The prop bet hits it big

I’ve been following the evolution of sports gambling for about a decade in my position as chair of Penn State’s sports journalism program.

Back when legal American sports betting was mostly confined to Las Vegas, the standard bets tended to be tied to picking a winner or which team would cover a point spread.

But ahead of the 1986 Super Bowl between the Chicago Bears and the overmatched New England Patriots, casinos offered bets on whether Bears defensive lineman – and occasional running back – William “Refrigerator” Perry would score a touchdown. The excitement around that sideshow kept fan interest going during a 46-10 blowout.

Perry did end up scoring, and the prop bet took off from there.

Prop bets are wagers that depend on an outcome within a game but not its final result. They can often involve an athlete’s individual performance in some statistical category – for instance, how many yards a running back will rush for, how many rebounds a basketball center will secure, or how many strikeouts a pitcher will have. They’ve become routine offerings on sports betting menus.

For example: As I write this, I am looking at a FanDuel account I opened years ago, seeing that, for the Green Bay Packers-Pittsburgh Steelers game currently in progress, I can place a wager on which player will score a touchdown, how many yards each quarterback will throw for and much, much more. As the game progresses, the odds constantly shift – allowing for what are called “live bets.”

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Returning to my student who lost the bet on Lawrence’s pass completion: It’s possible he’d placed a bet on Lawrence to throw fewer than a set number of yards. Or he could have been part of a fantasy league, which is also dependent on individual player performances.

Either way, a problem with prop bets, from an anti-corruption perspective, is that an individual can often control the outcome. You don’t need a group of players to be in on it – which is what happened during the infamous Black Sox Scandal, when eight players on the Chicago White Sox were accused of conspiring with gamblers to intentionally lose the 1919 World Series.

In the indictment against him, Rozier is accused of telling a co-defendant to pass along information to particular bettors that he planned to leave a March 2023 game early – a move everyone involved knew meant he would not reach his statistical benchmarks for the game. They could then place bets that he wouldn’t hit those marks.

In baseball, meanwhile, Luis Ortiz of the Cleveland Guardians was placed on leave during the 2025 season and is under investigation for possibly illegally wagering on the outcome of two pitches he threw. MLB authorities are essentially trying to determine if he deliberately threw balls as opposed to strikes in two instances. (Yes, prop bets have become so granular that you can even bet on whether a pitcher will throw a ball or a strike on an individual pitch.)

An exploding market with no end in sight

The popularity of prop bets feeds into a worldwide sports gambling industry that has experienced explosive growth and shows no sign of slowing.

Since the U.S. Supreme Court in 2018 ruled that states could decide on whether to allow sports betting, 39 states plus the District of Columbia have done so.

The leagues and media are more than just bystanders. FanDuel and DraftKings are official sports betting partners of the NBA and the NFL.

In the days after the Supreme Court ruling, I wondered whether journalists would embrace sports betting. These days, ESPN not only has a betting show, but it also has a betting app.

According to the American Gaming Association, sportsbooks collected a record $13.71 billion in revenue in 2024 from about $150 billion in wagers. A study released in February 2025 by Siena and St. Bonaventure universities found that nearly half of American men have an online sports betting account.

But those figures don’t begin to touch the worldwide sports betting market, especially the illegal one. The United Nations, in a 2021 report, reported that up to $1.7 trillion is wagered annually in illegal betting markets.

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The U.N. report warned that it had found a “staggering scale, manifestation, and complexity of corruption and organized crime in sport at the global, regional, and national levels.”

Who’s the boss?

In early October 2025, I attended a conference of Play the Game, a Denmark-based organization that promotes “democratic values in world sports.” Its occasional gatherings attract experts from around the world who are interested in keeping sports fair and safe for everyone.

One of the most sobering topics was illegal, online sportsbooks that feature wagering on all levels of sport, from the lowest levels of European soccer on up.

It sounded somewhat familiar. This summer at the Little League World Series, which my students covered for The Associated Press, managers complained about offshore sportsbooks offering lines on the tournament, which is played by 12-year-old amateurs.

And with so much illegal wagering in the world, the issue of match fixing was bound to come up.

One session screened a recent German documentary on match fixing. Meanwhile, Anca-Maria Gherghel, a Ph.D. candidate at Sheffield Hallam University and senior researcher for EPIC Global Solutions, both in northern England, told me how she had interviewed a professional female soccer player for a team in Cyprus. The player described how she and her teammates were routinely approached with lucrative offers to throw matches.

Put it all together – the vast sums of money at play and the relative ease of fixing a prop bet, let alone a match – and you cannot be surprised at the NBA scandal.

I used to think that gambling was just a segment of the larger sports industry. Now, I wonder whether I had it exactly backward.

Has sports just become a segment of the larger gambling industry?

John Affleck, Knight Chair in Sports Journalism and Society, Penn State

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This article is republished from The Conversation under a Creative Commons license. Read the original article.