Here's what to expect from this potential historic storm.
What regions of the East Coast will be impacted?
The storm could impact East Coast regions as far south as northern North Carolina to as far north as Boston, NWS lead meteorologist Rich Otto told ABC News today. Some 15 states were facing winter storm watches and DC and Baltimore were facing a blizzard watch.
Southern East Coast
Kentucky, Tennessee and parts of North Carolina are expected to get a combination of snow and freezing rain, which could create "significant icy conditions," Otto said.
Northern East Coast
ABC News meteorologist Melissa Griffin said that impact to northern East Coast regions, including Boston and New York, was still unclear but 6-12 inches were predicted in New York and 8-14 in Philadelphia. Boston was expected to get possibly 1-3 inches, she said.
Strong winds could also gust 30 to 50 mph. Coastal flooding is another concern in the New York City area, Griffin said.
Otto added that Boston will likely be at the outer fringe of the storm.
When will the storm hit?
The storm will first hit parts of the southern East Coast, mainly Kentucky and Tennessee, on Thursday night into Friday morning before moving east toward the Mid-Atlantic, including Baltimore, DC, eastern Virginia, southeastern Pennsylvania and southern New Jersey, Otto said.
A blizzard watch has been issued for the Mid-Atlantic region from Friday afternoon through late Saturday night, according to NWS.
How cold will it get?
Temperatures will likely stay in the upper 20s to lower 30s during the storm, Otto said, adding that areas that get more of the freezing rain from the storm can see temperatures closer to 32 degrees Fahrenheit.
Strong winds could make temperatures feel colder.
The bottom line
"This is a big storm, and it's important for people to take precautions and be aware," Otto said. "This system will likely impact a lot of travel, including flights and roads, so people need to be prepared."