The second nor'easter in a span of a week is dropping snow Wednesday across parts of the storm-weary East Coast, already pummeled by a deadly "bomb cyclone" last weekend.
More than 50 million people from Maryland to Maine are under winter storm warnings and watches. More than 2,000 flights have been canceled Wednesday.
The storm could bring heavy, wet snow and coastal flooding to the northern mid-Atlantic and the Northeast, possibly resulting in power outages and dangerous commutes Wednesday.
A couple of inches of snow already have been reported north of Baltimore and in northern New Jersey and parts of Pennsylvania. But peak snowfall is expected midday into the evening and also on Thursday when gusty winds and snow will mostly affect New England.
"This is just starting," CNN meteorologist Chad Myers said Wednesday morning in Ridgewood, New Jersey. "Don't wake up, look outside and say, 'Oh, we've got mist.' No, this is an all-day snow event."
The storm is expected to pack wind gusts of 30 to 50 mph. While a far cry from the 90-mph gusts recorded over the weekend, the strong winds could impede efforts to restore power in the region, where at least 100,851 customers were without electricity on Tuesday, according to power companies in the mid-Atlantic to New England.
How severe will this storm be?
It's not just the snow to be on the watch for. The National Weather Service in Boston tweeted that "the biggest concern is downed limbs, trees, power lines," with strong wind gusts and other risks such as lowered visibility and hazardous travel.
In New England, Interstate 95 could be a key dividing line, with areas to its east mainly getting rain and points west due to get as much as 2 feet of snow, CNN meteorologist Dave Hennen said.
Places separated by just 15 miles across I-95 could see a huge difference in snowfall totals, CNN meteorologist Judson Jones said, as uncertainty remains over how the storm might affect densely populated areas on the East Coast.
How will it affect major cities?
New York City could see 6 to 12 inches of snow, but public schools will be open, officials said. The heaviest precipitation will occur Wednesday morning into the evening, according to the National Weather Service's New York office.
Philadelphia could get about 8 to 12 inches of snow, according to snowfall estimates from the National Weather Service, which advised against unnecessary travel after 7 a.m. City schools will be closed Wednesday, and all after-school activities canceled.
Pennsylvania Gov. Tom Wolf announced a state of emergency for several counties in preparation for the storm.
Boston may see a slushy 2 to 3 inches of snow, with areas as little as 20 miles inland perhaps getting 10 or more inches. But if the rain/snow line moves farther east, Boston could get significant snowfall.
"It's a very dicey call for eastern MA. ... There's going to be a sharp line from little/no snow to several inches of accumulation," the National Weather Service in Boston tweeted.
How is it affecting travel?
Much of the 2,100 flight cancellations involve major airports in the Northeast, such as Newark, John F. Kennedy, LaGuardia, Boston and Philadelphia, according to tracking site FlightAware.
As for ground travel, New York City's Office of Emergency Management issued a hazardous travel advisory urging New Yorkers to "take mass transit if possible and allow for extra travel time."
Amtrak has also modified some of its services between Washington and Boston.
CNN's Jason Hanna, Taylor Ward, Joe Sutton and Rob Frehse contributed to this report.