"We're looking for a potentially very tricky rush hour," said meteorologist Mitchell Gaines of the National Weather Service.
Gaines said the Philadelphia region and parts of South Jersey will see between eight and 10 inches by the end of Monday.
And no need to put the shovel back in the shed after that just yet. Gaines said current forecasts call for rain and snow on Thursday as well.
"It's been pretty much the winter that never ends," Gaines said.
Philadelphia School District spokesman Fernando Gallard said district officials will decide late Sunday afternoon or evening whether schools will close Monday. Another snow day would be the seventh of the year.
Airlines are planning normal operations Sunday at Philadelphia International Airport but will update their plans as the storm gets closer, spokeswoman Victoria Lupica said. She encouraged travelers to check flights' status frequently for delays.
"Everybody needs to just be careful, and we'll see what happens," she said. "We're all watching the same bazillion tracking models."
Nearly five feet of snow has fallen in Philadelphia this year, making it the third-snowiest winter in the 130-year period of recording and six inches away from the 1995-96 second place.
Both Pennsylvania's and New Jersey's Departments of Transportation recorded all-time-high salt usage this winter.