Winter storm live updates: Heavy snow and ice creates dire travel conditions for commuters

NBC News meteorologist Michelle Grossman has the latest forecast, predicting temperatures well below average for the week ahead.

Miserable conditions for travelers persist into this morning, with 1,309 flights canceled across the United States and another 482 delayed, according to data from FlightAware.

FlightAware’s real-time “Misery Map” showed at 5.30 a.m. ET that the worst affected airport was Ronald Reagan Washington National Airport, with 72 flights canceled.

While the Central Plains and Mid-Atlantic are blasted with ice and snow, the South-East could see some strong to severe thunderstorms today, the National Weather Service warned.

There is a 1 in 5 risk of severe thunderstorms across the region through Tuesday morning, the service said, which would bring frequent lightning, severe wind gusts and isolated tornadoes.

As much as an inch of snow per hour is forecast to fall on Washington this morning, with travel conditions expected to deteriorate.

The National Weather Service office for Washington-Baltimore said that during the heaviest snow, between midnight and mid-morning today, “even primary and treated roads will be impassible.”

“It is highly recommended to postpone non-essential travel,” the office said.

Some 57 million people are under Winter weather alerts and advisories this morning as a significant Winter storm makes its way east.

The storm will move off the the Mid-Atlantic later today, but until then people in affected areas can expect “a tough morning commute and a tough evening commute,” NBC meteorologist Michelle Grossman said on “Early TODAY” this morning.