When Philadelphia issues a snow emergency, drivers along certain routes must move their cars. Here's what to know.

Snow started falling across New Jersey right on schedule early Sunday, with the heaviest snowfall along with a mix of sleet and freezing rain in some areas expected this afternoon. The National Weather Service made some final adjustments to forecast maps in its final forecast briefing for the massive winter storm.

Nationwide, slipping on ice sends about one million people to the emergency room each year, according to the U.S. Centers for Disease Control and Prevention. And after this week's heavy snow, doctors are warning that conditions could be especially dangerous.

"We are expecting light snow to fall at that time, potentially getting heavier by daybreak on Sunday," Lee said. "The heaviest snow will fall in morning hours of Sunday from 7 a.m. until about 1 or 2 p.m. in the afternoon."

Montgomery County Department of Transportation crews have begun clearing neighborhood roads after winter storm Fern dropped more than half a foot of snow, sleet and ice in parts of Montgomery County over the weekend.

A storm system is poised to bring a fresh coat of accumulating snow to Lancaster County − possibly the heaviest snowfall the county has seen in years.

As of 4 a.m., heavy sleet is falling in downtown Huntington.

Snow spreads across the state today, some of it heavy at times. There have been whiteout conditions reported Sunday afternoon. Snowfall rates could be 2-3″ per hour at times today, so much of the expected accumulations should pile up through Sunday.