"Heavy snow", "catastrophic ice accumulations" and "freezing temperatures": US weather services warned Friday of the arrival of a "major winter storm", which is expected to cause severe disruptions to transportation and the power grid across much of the United States.

The storm, which is expected to sweep across the central Great Plains from Friday night before moving towards the major cities of the East Coast by Monday, is expected to produce considerable amounts of snow, as well as sleet and freezing rain.

It risks causing "dangerous driving conditions, power outages, and damage to trees," the National Weather Service (NWS) predicted in its latest bulletin, Friday at 2:37 p.m. (7:37 p.m. GMT).

Meteorologist Ryan Maue predicts that "the next 10 days of winter will be the worst in 40 years across the United States."

"Think about where you can go, what you can do, and who needs even more help to survive the coming week. This is not an exaggeration or a joke," the expert said on X.

In Texas, many remember the winter storm of 2021, when a widespread power outage in the southern state left millions of homes without electricity for several days and caused more than 200 deaths.

"This time I have a generator, and I'm ready," Clinton Moore told AFP in a supermarket parking lot near Houston. "I don't think it will be worse than it was five years ago. It can't be."

- Ice accumulation -

Local authorities sought to reassure the public as the new storm approached.

The state's electrical grid "has never been more robust, never more prepared, and is fully capable of withstanding this winter storm," Governor Greg Abbott said Thursday, adding that he did not expect "in any way" any power outages from the grid itself.

Michael Webber, a professor of engineering at the University of Texas, told AFP that the Texas power grid was in "much better condition" than in 2021, although localized outages are to be expected.

Conditions could be more dangerous in the northeastern United States, where "ice accumulation is a major risk" for trees, whose branches can fall onto power lines.

Nearly 2,400 flights scheduled for Saturday have already been canceled across the country, including more than 1,300 originating from or destined for Dallas, Texas, according to the specialist website FlightAware.

Sports are not to be outdone, as the professional basketball league, the NBA, has decided to move forward a game on Saturday in North Carolina (southeast) between the Charlotte Hornets and the Washington Wizards, in order to get ahead of the storm.

- Polar vortex -

On his Truth Social platform, Donald Trump took advantage of the weather to once again express his skepticism about the existence of climate change.

"A record-breaking cold wave is set to hit 40 states. Rarely seen anything like this before. Could the environmental insurrectionists please explain to me: WHAT HAPPENED TO CLIMATE CHANGE?", the US president wrote.

The relationship between climate change and winter storms, when the polar vortex normally confined to the North Pole is pulled south, is not obvious.

But researchers note that the number of these storms has been increasing for the past 20 years. This could be due to the fact that the Arctic is warming faster than the global average, an uneven warming that some scientists believe contributes to facilitating the spillover of the polar vortex onto North America.

However, experts warn against overly simplistic conclusions that would directly link this phenomenon to human-caused climate change.

"It is more difficult to establish this connection over a longer period, simply because I think we don't have enough data," says Jason Furtado, a meteorologist at the University of Oklahoma.