Large parts of the southern US are braced for a rare winter storm expected to bring below-freezing temperatures, heavy snow, and freezing rain and sleet, forecasters have said.
More than 55 million people in the Gulf Coast region could be affected, Sky News’ US partner, NBC News, has reported.
Temperatures are expected to be significantly below the January average for most locations, according to the US National Weather Service (NWS).
It warned of “many record lows on Wednesday morning, especially along the Gulf Coast and into the Tennessee Valley”.
The forecast has prompted officials to issue rare warnings that are more common to those living in the north of the country.
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Between three and seven inches of snow (7.5cm to 15cm) is set to fall over parts of southern Mississippi and southeast Louisiana, including New Orleans, heading into Tuesday, the NWS said.
Thick snow fell on parts of the US east coast as temperatures plunged to well below normal on Monday.
Millions of people, primarily across the southern US and mostly living in an area from Texas to Florida, are facing some type of weather hazard, NWS meteorologist Marc Chenard said.
Around 21 million people are under a winter storm warning, Mr Chenard added, while about 170 million people in an area from the Rockies eastward are under either an extreme warning or a cold weather advisory.
A state of emergency has been declared, and many schools shut on Tuesday in Georgia, Louisiana, Mississippi and Alabama.
Almost 600 domestic and international flights had been cancelled by Monday evening, online tracker FlightAware said, along with nearly 6,500 delays.
More than 1,700 such cancellations also were posted for Tuesday.
With the icy conditions expected to last until at least the middle of the week, flights were suspended at both of Houston’s airports from Tuesday.
Louisiana Governor Jeff Landry warned people to avoid driving “unless you absolutely need to be on the road”.
On the opposite coast of the US, people in the Los Angeles area are being warned to expect a resumption of the Santa Ana winds this week, making further fires likely, even as the city tries to recover from the deadly blazes earlier this month.
The highest red flag warning – a particularly dangerous situation alert, warning of extreme danger of fire spread due to dry conditions and low humidity – is in place until 10am local time (6pm UK time) on Tuesday for a large part of Ventura and Los Angeles counties.
Gusts of up to 100mph (161 kph) are forecast.
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A particularly dangerous situation warning is rarely used, but this is the fifth NWS has issued since November.
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At least 27 people are known to have died and more than 13,600 structures destroyed in fires which began earlier this month and which have not all been fully extinguished.