Philly may end January with just a trace of snow, as another threat passes. One last chance on Sunday?

Protected by the Appalachians and far closer to the heat-retaining Atlantic Ocean than the snow-making waters of the Great Lakes, Philadelphia is not an especially snowy place.

Despite those obstacles, the city can almost always count on at least some measurable snow in January, almost as surely as cars will double-park in South Philly.

But for the first time in a generation, it’s entirely possible that January 2021 will end with no more than a trace officially. That has happened in only a handful of years in records dating to 1885, and not since 1995.

Sleet, freezing rain, and some random flakes fell north and west of the city on Tuesday, and a winter weather advisory was extended until 4 a.m. Wednesday in the outer areas of Bucks, Chester, and Montgomery Counties.

» READ MORE: Snow is snubbing Philly in January, and February is looking mild across the nation

But, yet again, snow eluded Philadelphia, which awoke Tuesday to a generic cold rain with temperatures in the mid-30s and nary a flake sighting.

And, yet again, we learned that in meteorology the term model behavior very often is no compliment. Recall that last week some were seeing a potentially significant snowfall Monday into Tuesday.

Now, the model guidance says a major winter storm could affect the region Sunday into Monday. Somehow, that sounds familiar.

By the time a once-powerful storm that crowned parts of the Midwest with double-digit snows came close enough to affecting the Philadelphia, it was more or less spent.

Still, on Monday forecasters had been confident that the region would get its first measurable snow of the month, albeit a paltry amount, followed by some ice.

» READ MORE: When winter doesn’t come: Here are the winners and losers of Philly’s nearly snowless season

However, dry air held on stubbornly overnight, said Chad Shafer, a lead meteorologist in the National Weather Service’s Mount Holly office, and by the time the precipitation arrived, the upper atmosphere was a touch too warm for snow.

“The models have just been too aggressive in bringing the precipitation from the get-go,” Shafer said.

Identifying the rain/snow/ice line was a tough call, said Dave Bowers, a meteorologist with AccuWeather Inc., as temperatures 3,000 to 6,000 feet in the atmosphere were “literally hugging the freezing line.”

As expected, the storm did spawn a weak secondary low-pressure system off the Carolina coast. It generated weak winds from the northeast that kept temperatures near freezing well inland, prompting the weather service to extend its winter weather advisories.

However, it moved out to sea and never had a chance to become a snow-making nor’easter.

Shafer said that in recent weeks the upper-air pattern has set up in such a way as to shunt storms to the south. Meanwhile, to the north, west-to-east winds from the Pacific have dominated, the result of the La Niña cooling of surface waters in the tropical Pacific.

» READ MORE: Snow squalls cross region, and Philly gets its first ‘trace’ of the month

“Arctic air has been practically absent,” said Bowers.

While not Arctic level, Philadelphia will be getting quite a substantial cool-down starting Thursday, with daytime temperatures through Saturday struggling to get past freezing.

On Friday morning, the forecast low is 19. That would be the first time in more than a year that the official reading in Philadelphia has dropped to the teens.

Should that prospective coastal storm actually take shape Sunday, cold air would be in place, with forecast highs in the mid-30s. Shafer said the pattern that has been blocking storms from coming north is due to relax.

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However, it is not at all clear how much of any precipitation would fall as snow. And given the models’ tendency to be overanxious on arrival times, Shafer said it is uncertain whether it would get here before 12:01 a.m. Monday, which would be Feb. 1.

“Sunday might be precipitation-free,” he said. “I would not be surprised if Sunday turned out to be an oh-fer.”