CNN
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About 40 million people from Texas to the Carolinas are under winter weather alerts as a rare winter storm brings freezing temperatures and potentially historic snowfall to cities unaccustomed to harsh cold.
In Texas, temperatures fell below freezing Monday night as winter began across the state.
Snow showers widened early Tuesday and could intensify throughout the morning – with an expected fall of an inch per hour, mixed with freezing rain and sleet.
The National Weather Service on Monday described the sweeping system as “a generational winter storm” and urged those in its path to take its impact seriously.
Travel overnight and Tuesday will be “extremely dangerous, if not impossible, for much of the region, and travel is strongly discouraged,” the service said.
Texas snowfall is expected to move east to New Orleans Tuesday morning before spreading to parts of Mississippi, Alabama, Georgia, the Carolinas and western Texas. Florida throughout the day, where snowfall totals are expected to break records not seen since at least 1963. and possibly rivaling records from the late 1800s.
This rare winter storm comes as more than 220 million people in 40 states across the continental United States are affected by frigid air, with the Upper Midwest and Northern Plains likely to experience similarly low wind chill temperatures than 55 degrees below zero.
These temperatures, if exposed to the skin, can cause hypothermia in just 5 minutes.
Authorities in affected southern states have warned people to stay off the roads, leave faucets running to prevent pipes from freezing, check batteries in smoke and carbon monoxide detectors and refrain from to use stoves to heat homes.
These precautions, however, are more familiar to people living in northern states and not the South, where unusually cold conditions could strain infrastructure and resources.
“Most of us have never experienced this combination of bitter cold and heavy snow in our lives,” Louisiana climatologist Jay Grymes said Monday.
Southern cities like Houston, Atlanta, Jackson, Mississippi, and Memphis, Tennessee, could also see below-freezing temperatures Tuesday, putting pressure on pipes that could freeze and burst.
Ahead of the winter storm, Houston Mayor John Whitmire on Sunday urged residents to protect their water pipes, noting that the city’s water system is already “fragile” with more than 1,000 water leaks active in Houston.
“Let me emphasize preparing your pipes,” Whitmire said. “Wrap your pipes if possible.”
The governors of Louisiana, Georgia, Alabama, Florida and Mississippi declared states of emergency, while Texas authorities ordered state agencies to mobilize resources to deal with the rare falls of snow.
Arkansas has sent 12 dump trucks equipped with snow plows to Louisiana, Louisiana Gov. Jeff Landry said Monday during a news conference on storm preparations.
“This is the time when you can cook yourself a big pot of gumbo,” Landry said.
Air and road travel have been disrupted; no more schools closed
Forecasters say the Interstate 10 corridor could see snowfall totals of 3 to 6 inches, further crippling travel on the roads for several days.
There were more than 1,700 flight cancellations within, to or from the United States as of early Tuesday, with most of those flights coming from Texas and Louisiana, according to flight tracking site FlightAware.
Houston’s two main airports, George Bush Intercontinental and Hobby, will close Tuesday, while Hartsfield-Jackson Atlanta International Airport, the world’s busiest, pretreats road and airfield surfaces in preparation for winter conditions , according to spokesperson Andrew Gobeil.
“The Emergency Operations Center will be activated at 6 a.m. Tuesday morning and will remain operational throughout the event,” Gobeil said Monday. “Passengers are requested to arrive at the airport at least two and a half hours before domestic departure times unless otherwise instructed by their airline.”
NASA’s Johnson Space Center in Houston announced it would be closed Tuesday and Wednesday due to severe weather conditions. Port Houston said its facilities would also be closed Tuesday.
Schools are closed in several states, including Georgia, Louisiana and Texas.
Gwinnett County Public Schools, Georgia’s largest school district, has moved all of its classes online. While the Houston Independent School District, the largest in the Lonestar State and the eighth largest in the nation, will also be closed through Wednesday, Whitmire said.
Several Washington, D.C.-area schools announced closures and delayed their openings for Tuesday, including Fairfax County Public Schools — among Virginia’s largest counties.
In Florida, where schools rarely close due to winter weather, dozens of elementary and middle schools and state universities will close Tuesday.
CNN’s Mary Gilbert and Lauren Mascarenhas contributed reporting.