Snow around Christmas, always a longshot, isn’t entirely out of the question as snowpack chills East

SEPTA has weathered rougher days, even when it wasn’t snowing. Power outages were negligible. Schools? Sorry, kids, laptops don’t have snow numbers.

Close to 10 inches of snow and ice was measured in Elverson, Chester County, and Philly’s official 6.6 inches was 22 times what fell all of last winter. The heavy snows were spiced with hours of stinging sleet pellets, blizzard-like conditions for a period Wednesday afternoon, and all followed by an overnight hard freeze.

Given all that, the most significant winter storm since March 2018 was far less disruptive around here than its resumé might have indicated.

But meteorologists say that its aftermath could have lingering impacts — on the atmosphere. They could persist into January, and snow around Christmastime, always a long shot, isn’t entirely out of the question, said Bob Smerbeck, a senior meteorologist with AccuWeather Inc.

» READ MORE: Philly region experiences its first major snowstorm in 1,000 days

The Wednesday-Thursday special has left an immense snow cover in the East — more like concrete around here — that is going to take its time vanishing. “That will certainly have an impact on the pattern,” he said.

The snowpack at the very least is likely to affect temperatures for the next several days, said Greg Postel, a winter-weather expert with the Weather Channel.

“It was definitely a blockbuster storm,” said Smerbeck, with 40-plus inches in Binghamton, N.Y. “There’s just an insane amount of snow.” Snow cover was evident Thursday from the Virginia mountains to northern New England.

Snow refrigerates the overlying air and is about the most efficient sun-repellent on earth, which is one reason why the diminishing snow and ice cover in the Arctic and the resultant warming has been such a cause for concern. Winds over a snow cover have more bite.

The snowpack might have some subtle effect on storm traffic, said Smerbeck. Storms tend to form along the borders of warm and cold air, and snow cover can alter where those lines form.

» READ MORE: Philly rarely gets a white Christmas, but we’re about due for one

He and his colleagues expect an active pattern into January with “clipper systems” that cross the country and sometimes redevelop as coastal storms as they approach the Atlantic, perhaps three or four of them. While New England would be a favored target, it’s possible that they could re-form far enough south to affect Philadelphia.

The atmosphere sometimes has the attention span of a snowflake in April, but meteorologist Tony Gigi, now retired from the National Weather Service, analyzed the 11 winters since 1953 in which an early-season snowfall of 6 inches or more inches occurred in Philadelphia.

In 10 of those winters, at least one snowfall of 10 inches or more occurred later in the winter.

“I do believe that Mother Nature likes to foreshadow the weather,” said Judah Cohen, scientist with Atmospheric and Environmental Research, in Massachusetts.

Cohen said the pattern might signal a weaker polar vortex this winter, which would mean more Arctic intrusions into the midlatitudes, although not necessarily in the East. Last winter, the vortex spent most of the season spinning around the North Pole, confining cold air up that way.

» READ MORE: Feds’ updated winter forecast favors warmth here and in most of the nation, especially December

The preseason consensus among the seasonal outlooks was for a generally mild winter with below-normal snowfall.

The outlooks referenced the La Niña event, the cooling of surface temperatures in the tropical Pacific, which on average affects the atmosphere in such a way that it discourages the nor’easters that are the source of Philadelphia’s major snowstorms.

“It’s important,” said Postel, but “there’s lots more out there that’s not La Niña.”

Smerbeck pointed out that AccuWeather had called for 10 to 15 inches of snow this winter for Philly. As of Thursday, that might be in some trouble, he acknowledged.

The computer models and their human interpreters did quite well at foreseeing the storm well in advance and that the snow/no-snow boundaries would be dramatic.

The heads-up — with a big assist from the coronavirus restrictions that have kept more people at home — cut down on impacts. Some trains were canceled on SEPTA Regional Rails, and bus routes rerouted. City trash collection was postponed until Friday, but that was primarily due to trash trucks being deployed for snow-fighting.

» READ MORE: Much has changed in 2020. The magic and mystery of snow persist.

It poured at the Shore, as expected. But on the mainland, heavy snow fell farther east than anticipated, with several inches well into Burlington, Camden, and Gloucester Counties.

The front-end snow was robust, and the cold air at the surface was more tenacious than expected in South Jersey and along the river.

To the west, warm air aloft arrived sooner and more vigorously than expected and turned the snow to sleet hours before its time, cutting into accumulations.

The sleet also was a break for utilities and their customers; sleet tends to bounce off wires and tree branches.

The forecast calls for a run of dry and chilly weather for the next several days, with a warm-up the middle of next week. Then, “it looks like another cold shot,” said Postel.

And with the arrival of that Arctic front, a storm could form to bring rain or snow to the region, Smerbeck said.

However, that’s a week away, and on Wednesday forecasters had more than their hands full trying to figure how the atmosphere would behave during the next seven hours.