The snowfall could easily cause more than $1 billion in damage and paralyze the Eastern third of the nation, said weather service director Louis Uccellini .
“It (has) the potential to be an extremely dangerous storm that can affect more than 50 million people,” said Uccellini.
Snowfall as heavy as 1 to 3 inches (2.5 to 7.6 cm) an hour could continue for 24 hours or more, said meteorologist Paul Kocin with the National Weather Service’s Weather Prediction Center.
Some 12 to 18 inches (30-46 cm) of snow was also predicted for Philadelphia, and 8 to 12 inches (20-30 cm) in New York.
Almost 5,000 flights have already been cancelled for Friday and Saturday in the U.S., according to Houston-based FlightAware.
The blizzard could rank near the top 10 to ever hit the region, according to the National Weather Service.