Big Arctic warm-ups can lead to bouts of snow in Philly. One may be coming.

For all the rightful attention attracted by the potent El Niño warming in the tropical Pacific, the fate of the winter in the Philly region — and for significant portions of the nation — may rest with a sudden and dramatic warm-up in a region where wind-chills can reach 180 degrees below zero Fahrenheit.

At least a few computer models have hinted at the possibility of a so-called sudden stratospheric warming, or SSW, event over the Arctic, which could “load the dice” in favor of wintry weather in the Eastern United States, said Laura Ciasto, a scientist with NOAA’s Climate Prediction Center. But other models have splashed water on the potential.

If the sudden stratospheric warming does happen, the most likely time would be the end of December, with effects on the weather at the populated lower latitudes — where we live — appearing a few weeks later, said Judah Cohen, polar scientist with Atmospheric and Environmental Research in Massachusetts.

» READ MORE: Philly winters aren't what you think. Anything can, and does, happen

If the event doesn’t happen, he suggested in a recent blog post, it could be a postholiday gift for winter-phobes. As for the long-suffering snow lovers, if one doesn’t develop, he wrote, “I have a hard time seeing any chance of widespread meaningful cold” this winter throughout the Northern Hemisphere.

That ocean of air that gives us life is a turbulent sea where vertical and horizontal waves of unimaginable force crash on the shores of the upper atmosphere.

When upward-moving waves from the troposphere, 5 to 9 miles over the Arctic, smash into the stratosphere, 10 to 30 miles up, they can weaken the polar vortex, the west-to-east winds that imprison cold air in the highest latitudes, said Ciasto.

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Those winds can blow 100 mph, driven by the contrast between the frigid air in the winterlong darkness and the warm air in the stratosphere over the tropics, according to NOAA researchers. A disturbance can weaken those winds, and cause a “stretch” or even a “splitting” of the polar vortex, delivering cold air to Philadelphia and other midlatitude regions.

On average, sudden stratospheric warming events — discovered in 1952 — have occurred about three times every five years, with four in the last six years. Researchers say it is too soon to detect any global warming signal in their frequency.

The aftereffects can last for several weeks.

In their analysis of the warming episode of January 2021, Ciasto and NOAA research colleague Amy Butler reported that temperatures in the stratosphere over the Arctic dropped more than 65 degrees Fahrenheit from mid-December to the first week in January. (It still wasn’t quite beach weather up there: It didn’t get above 25 below.)

The polar vortex winds dropped from 100 mph to negligible speeds and reversed direction for a time, allowing for the cold spillage.

A few weeks later, it was snowing at the Vatican, and Philadelphia had one of its snowier Februaries on record, with some places outside the city receiving up to 50 inches that winter.

No, it doesn’t always work that way. A sudden stratospheric warming occurred in February 2023 in a winter when Philly recorded an official 0.3 inch of snow.

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No, says Ciasto. It’s an atmospheric jungle up there, and forces are always competing and interacting. El Niño almost certainly will be a force throughout the winter, with meteorologists predicting that the strong west-to-east winds it is generating will incite an active East Coast storm track. The recent storms may be harbingers.

But nothing acts in isolation, Ciasto said.

“Attributing specific events to these climate phenomena is complex and a continuing source of active research,” she said. “We tend to think about impacts on the weather [whether the U.S. or elsewhere] in more of a probabilistic sense.

“SSWs don’t guarantee that we will experience cold for the East Coast, but it can tilt the odds in that favor. Another way to think of it: SSWs can load the dice for wintry weather across the East Coast, but it can’t necessarily tell you when and where you will hit snake eyes.”

While forecasting stratospheric warming outbreaks remains very much a work in progress, Ciasto said, “Many of the forecast models that we use can reasonably predict SSWs a little more than two weeks in advance.”

Of course, computer model often squabble, and are prone to change their minds.

And getting a handle on the potential impacts should one occur is a whole other wild card, researchers say.

Officially, Philadelphia hasn’t had an inch of snow since Jan. 29, 2022.

The consensus among long-range forecasters is that the region eventually should see snow in the range of the seasonal average, about 23 inches, maybe even a little more, given the El Niño storm track.

But Cohen says that without a sudden stratospheric warming, it could end up being another dream winter for the region’s highway crews.