NBC News published this article:

The deadly blizzard that has killed at least 57 people across the United States was still producing "extremely heavy snow" on Tuesday, the National Weather Service said.

Wind gusts of 20 to 30 mph could rapidly deteriorate visibility, it said in a 5:45 a.m. ET bulletin, adding that parts of storm-weary New York were experiencing snowfall of 1 to 2 inches per hour.

"The snow will accumulate so rapidly that it will be extremely difficult for the road crews to keep the roads clear," the weather service said later in the morning.

The blinding snowstorm particularly targeted Erie County, New York, which accounted for almost half the death toll at 27, including 18 in Buffalo.

A snow blanket has left roads impassable, Buffalo County Executive Mark Poloncarz said in a news conference Monday, adding that he hoped a driving ban that has been in place for days could be lifted soon for some suburbs. 

But forecasters said in a 3:15 a.m. ET bulletin Tuesday that parts of western New York could record as much as 8 more inches of snow, with up to 5 inches in Buffalo. Since July 1, Buffalo has experienced at least a hundred inches of snow, making it the snowiest start to any season on record.

Lake effect snow occurs when cold air passes over the unfrozen and warmer lake water, transferring moisture and warmth to the lower parts of the atmosphere. The air then rises to form clouds, resulting in intense snow.

President Joe Biden on Monday approved an emergency declaration for New York.

Nationwide, temperatures plummeted and huge snow drifts have left cities in whiteouts resulting in power outages, cancellations of thousands of flights and residents trapped in their homes without food. 

Stretching from the Great Lakes near Canada to the Rio Grande along the Mexican border, the storm had killed at least 57 people as of Tuesday morning, according to an NBC News tally. The deaths were recorded in 12 states: Colorado, Illinois, Kansas, Kentucky, Michigan, Missouri, Nebraska, New York, Ohio, Oklahoma, Tennessee and Wisconsin. 

About 2,900 flights into and out of the U.S. had been canceled in the country on Tuesday as of 6 a.m. ET, according to the flight-tracking website FlightAware. More than 2,500 of those canceled flights were Southwest Airlines.

On Monday, the travel-heavy day after Christmas, Southwest had canceled 2,900 flights, amounting to 70% of its entire schedule, stranding furious passengers across airports.

In Jackson, Mississippi, broken pipes left thousands of residents without running water Monday as the city struggled to return pressure to its frail water system.

The storm was expected to gradually improve over the week, forecasters said.

"Lingering lake-effect snows downwind from Great Lakes will become less intense and fade on Tuesday," the weather service said in its 2:59 a.m. ET bulletin Tuesday. Temperatures in the East and Midwest were also expected to moderate over the next few days, it added.

A tweet from the NWS though warning of flooding from the melting snow as temperatures rise.