Scattered reports of light snow - from Baltimore to Harrisburg to Millville - started coming in by 3 p.m. Shortly after 4 p.m., flakes were falling in Center City.
Commuters could see flurries or light snow on the way home, but the steady, accumulating stuff will phase in around 7 p.m., said meteorologist Anthony Gigi of the National Weather Service.
Since that's the time for the Sixers game at the Wells Fargo Center, fans might consider public transportation. (See SEPTA.org.)
Gigi knocked down the totals a bit, estimating four to six inches for the city and its suburban counties, with more to the north and east.
The initial assault is coming from the off-shore reawakening of a system that dumped misery across the South. Overnight, a snowmaker from the Midwest will join in, producing heavy snow and blustery winds.
From the Trenton area to the northern Jersey Shore, up to 10 inches might fall. New York City could get a foot, Boston a foot-and-a-half.
Parts of Delaware, though, might get only 2.
The southern part of the Shore, and parts of Delaware, could see some sleet and rain in the beginning, and winds could be a problem along the coast, reducing visibility and causing drifting in areas with only snow, said Tom Kines, a meteorologist with State College-based AccuWeather.
In Philadelphia and its suburbs, snow could last until about 6 a.m., leaving Wednesday morning likely in a mess. Drivers should face covered cars and driveways and unplowed neighborhood streets, as well as packed and frozen snow on other roads. School closings can be expected.
Even after the snow stops falling, winds could still whip it around, causing continuing problems for plows, said Gary Szatkowski, head meteorologist at the Mount Holly office of the National Weather Service.
The snowpiles are likely to linger for days. After a high in the mid-30s Wednesday, temperatures won't be above freezing again until Sunday.
Another storm could arrive early next week, but that one might involve rain, Kines said.
Weather.com's 10-day forecast mentions snow for three straight days, starting next Monday.
For more on the forecast, go to http://go.philly.com/weather.