NYC gets hit by the biggest snowstorm in 2 years. It's part of a growing trend of extreme weather events.

• Winter storm Lorraine brought heavy snow, high winds, and cold temperatures to New York on Tuesday.
• The storm hit just a couple days after a weekend of warm, springlike temperatures.

Millions braced for snow on Tuesday as winter storm Lorraine moved up the East Coast, delivering high winds, cold temperatures, and heavy snowfall from Philadelphia to Boston.

New Yorkers were reeling as the sudden onslaught covered the city with one to three inches of accumulation, its biggest snowfall in over two years.

Lorraine came on the heels of an unseasonably warm weekend in New York, where temperatures reached nearly 60 degrees Fahrenheit on Saturday — a balmy 17 degrees warmer than the NYC average high for this time of year.

Experts say the storm is part of a growing trend they call “whiplash weather.”

These episodes of erratic weather can wreak havoc on infrastructure, disrupt travel, and can even be deadly. For example, the “Texas Freeze” of February 2021, which suddenly sunk temperatures after a streak of above-average warmth, killed 246 people.

More recently, in January, Montana saw a 94-degree temperature swing in the span of just 15 days, and Minnesota plunged into a deep freeze mid-month after experiencing record-breaking warm temperatures in December.

Winter storm Lorraine is the latest event in this growing trend, which experts say is driven largely by global climate change. But to understand how whiplash weather is reshaping winter in the US, scientists are looking to the Arctic.

The polar vortex is like a figure skater

For years, climate scientists thought that rising global temperatures would make weather more erratic in every season except for winter, explained Judah Cohen, a climatologist at MIT. In some ways, it makes sense: rising global temperatures should create milder winters with fewer storms.

But in reality, the impact of climate change on winter weather is much more complex.

“There’s another influence that we didn’t consider as recently as a decade ago: the way that climate change is occurring can influence the behavior of the polar vortex,” he said.

The polar vortex is a large area of low pressure and cold air above the North and South Poles. It’s called a “vortex” because it flows counterclockwise in a continuous circle that keeps this cold air trapped at the poles.

Think of it like a figure skater, said Cohen. To spin very fast, a figure skater has to tuck her arms, legs, and head into the center of her body. The same thing happens with the polar vortex. When it spins fast, the cold air stays tucked close to the center of rotation.

But when the polar vortex slows down, its grip on this cold air loosens. This is what triggers Arctic outbreaks like Lorraine: when cold air in the polar jet stream surges down to lower latitudes.

Some loosening and tightening of this grip is normal. The polar vortex tends to weaken in the summer and strengthen in the winter. But climate change is disrupting this cycle.

“The way that climate change is happening in the Arctic is favoring this weak polar vortex,” Cohen said. “That’s when you get an increase in the probability of severe winter weather, cold, or snowfall.”

Winter storm Lorraine is a direct result of this phenomenon. Last week, the polar vortex was strong and tight. But this week, it stretched out like a rubber band, Cohen said, sending a blast of cold temperatures and snowfall to the East Coast.

Arctic warming is disrupting the polar vortex

Climate change is increasing global temperatures worldwide. But no place is warming faster than the Arctic. Research suggests that the North Pole has warmed two to four times faster than the rest of the world since 1990.

This rapid warming is likely what’s causing more frequent and extreme disruptions to the polar vortex, and unleashing the polar jet stream onto the mid-latitudes, Cohen explained.

That’s because rising Arctic temperatures have destabilized the way that air flows around the world. In particular, the warmer temperatures are amplifying a naturally occurring “wave” of air that flows across Eurasia. When this amplified wave crashes into the polar vortex, it disrupts its circulation.

When this happens, the US and Canada face the brunt of the wintry blast. “North America is really ground zero for these types of events,” Cohen said.

That could explain why the US is still experiencing episodes of record-breaking low winter temperatures despite an overall rise in annual average temperatures, Cohen explained.

The year 2023 may have been the hottest year on record, but some states still faced brutal cold. In February of that year, Boston recorded its coldest day since 1957, and Portland, Oregon saw its second snowiest day on record.

Brace for weirder winters

Whiplash weather doesn’t seem to be going away any time soon.

With the progression of climate change, the Arctic will continue to warm, and polar vortex disruptions could become increasingly common.

“That doesn’t promise that it’s going to continue into the future,” Cohen said. “But a number of these events could continue as long as the conditions that support these disruptions continue.”

Adapting to this new normal presents a unique challenge, as the erratic nature of whiplash weather makes it difficult to predict, which adds to the threat it poses to ecosystems, infrastructure, and human health, according to Jennifer Francis, an atmospheric scientist at Woodwell Climate Research Center.

Demands for heat and electricity can shift drastically. And people can find themselves suddenly caught in dangerous conditions.

“After a long dry spell, a sudden flip to heavy precipitation may catch people and communities unprepared,” Francis told BI in an email.

And as climate change continues to warm the Arctic, Francis anticipates we will see more of these events.

“Unless we can quickly and drastically reduce greenhouse gas emissions, we'll see a very distinct increase in weather whiplash events in decades to come,” Francis wrote.