The region’s trees that at long last are tastefully undressed for winter could soon be wearing a coat of snow, a parting gift from a complex storm that has tormented much of the country and is likely to disrupt homebound trips for hundreds of thousands of holiday travelers.

The National Weather Service in Mount Holly has issued a winter weather advisory in effect from 3 a.m. to 1 p.m. Sunday for potential icing for Philadelphia and counties west of the Delaware River, and a winter-storm warning for heavy snow and ice in northeastern Pennsylvania and northwestern New Jersey into Monday night.

“It’s worrisome that it’s a high-travel weekend,” said PennDot spokesperson Brad Rudolph, adding that this would be the agency’s first full-scale call-out of the season.

He said an armada of state salt trucks would be dispatched during the early-morning hours.

When the precipitation begins, probably around daybreak, temperatures in the region will be at or near freezing, the weather service says, and it could start as a mix of sleet and freezing rain, with perhaps an icy coating in the immediate Philadelphia area and a more dangerous lacquering to the north and west.

It is at least possible that the advisory will be expanded to the south and east, said Lee Robertson, a weather service meteorologist in Mount Holly.

But temperatures should make it into the 40s in the afternoon; winds will be from the east, and ocean temperatures are in the upper 40s.

And the weather service advisory notwithstanding, icing should not be a major threat in and around Philadelphia, said AccuWeather Inc. meteorologist Alan Reppert.

The forecast is likely to undergo tweaks and possibly more substantial changes Sunday into Monday as the weather service calls it “a very complex, two-phased winter storm.”

The storm, which has affected areas across the country, is expected to gather a second wind as it redevelops somewhere near the Delmarva coast, draws in colder air, and transforms into a major snowstorm for the interior Northeast.

Robertson said Philadelphia could get up to an inch of backlash snow Monday night. Reppert, however, said in all likelihood the region would see nothing more than some wet flakes.

Regardless of what does or doesn’t happen, the storm, which has been blamed for at least three deaths, including that of a 5-year-old in Arizona, already has had major impacts on travel plans.

Up to a foot of snow was expected from the northern Plains to the Upper Midwest. Duluth, Minn., issued a “no travel advisory” for Saturday for a storm that it termed “historic.”

According to Flightaware.com almost 11,000 flights were delayed on Saturday.

Expect more on Sunday.