Winter storm headed to Northeast: What to know about the latest forecast

Millions of residents from the Midwest to Northeast are bracing for an intense winter storm this weekend that will likely bring heavy snow, sleet, freezing rain and strong winds.

Some areas could see over a foot of snow.

Over 350 flights were cancelled and more than 2,200 were delayed Friday. Amtrak has also modified service for the weekend.

In Pennsylvania, where residents are set to see snow and freezing rain, Gov. Tom Wolf has signed a state of emergency declaration.

"We want to be aggressive in managing this storm, during which snowfall rates could exceed one to two inches per hour," Wolf said in a statement. "If you do not have to travel during the storm, please avoid it."

New Jersey Gov. Phil Murphy has also declared a state of emergency, telling reporters the weekend is "a big window with a lot of variability around it."

Behind the storm, an Arctic blast is forecast to spill into the central and eastern U.S., delivering the coldest air of the season and brutally cold wind chills Monday morning.

The wind chill is expected to fall to negative 20 degrees in New York City on Monday and negative 29 degrees in Cincinnati.

ABC News' Brendan Rand and Christine Theodorou contributed to this report.