'Bombogenesis' snowstorm lashes the East Coast, canceling thousands of flights and packing hurricane-force winds

• The East Coast is hunkering down as a blizzard with heavy snow and winds whips through the weekend.
• The storm marks the first major blizzard to hit the East Coast in four years.

A heavy snowstorm with hurricane-force winds is threatening to rattle the East Coast, prompting thousands of flight cancellations and state-of-emergency declarations.

Forecasters predict the nor'easter will bring a dangerous mix of heavy snow and winds for millions of Americans. In some areas along the East Coast, there will be winds reaching up to 70 miles per hour, forecasters say.

The storm marks the first major blizzard to hit the East Coast in four years. Forecasters said it's developing bombogenesis conditions, meaning cold air and warm sea air mix together and cause a drop in atmospheric pressure, eventually leading to the formation of a bomb cyclone.

Five governors have declared states of emergency, urging people to stay indoors and off roads.

"This one is a big one," New Jersey Gov. Phil Murphy said during a Friday news conference. "We're certainly hoping for the best but we are, without question, preparing for the worst."

Gov. Larry Hogan of Maryland mobilized the state's National Guard to prepare for potential emergency evacuation efforts. The state could receive up to 12 inches of snow.

Thousands of flights have been cancelled along the East Coast, according to FlightAware data.

"Heavy snow and powerful winds will spread from the Mid-Atlantic coast to the Northeast coast throughout the day," the National Weather Service said on Saturday. "The combination of heavy snow rates and strong winds will produce dangerous blizzard conditions across portions of the Mid-Atlantic and New England coasts, from Virginia's Eastern Shore to eastern Maine, where Blizzard Warnings are in effect."

Travel across the northeast region will be "nearly impossible" because of "whiteout conditions," according to the NWS.

Some areas like Boston can expect to experience coastal flooding, the NWS said.