Deaths in Louisiana as storm spawns tornadoes in southern US

A vast and volatile storm system ripping across the US has killed at least three people in Louisiana, spinning up tornadoes that battered the state from north to south, including the New Orleans area where memories of 2021's Hurricane Ida and a tornado in March linger.

Several injuries were reported around Louisiana by authorities and more than 40,000 power outages statewide as of Wednesday night.

The punishing storms barrelled eastward on Wednesday after killing a mother and son in the northwestern part of the state a day earlier.

The system spun off a suspected tornado that killed a woman on Wednesday in southeast Louisiana's St. Charles Parish and another that pummeled parts of New Orleans and neighbouring Jefferson and St. Bernard parishes — including areas badly damaged by a March tornado.

Forecasters said a severe threat of more tornadoes would continue overnight into parts of Mississippi, Alabama and the Florida Panhandle.

New Orleans emergency director Collin Arnold said business and residences in the city suffered significant wind damage, largely on the Mississippi River's west bank. One home collapsed.

He said four people were injured there, adding, "The last word we had is that they were stable."

"Several homes and businesses have suffered catastrophic damage," the Jefferson Parish Sheriff's Office said in a statement from that large suburb west of New Orleans.

It took hours for authorities to find the bodies of a mother and child missing after a tornado swept away their mobile home on Tuesday in Keithville, south of Shreveport.

"You go to search a house and the house isn't even there, so where do you search?" Governor John Bel Edwards told reporters, noting the challenge faced by emergency responders as he toured a 1.6-kilometre path of destruction in rural Keithville.

He had issued an emergency declaration earlier in the day.

The Caddo Parish Coroner’s Office said the body of 8-year-old Nikolus Little was found late on Tuesday night in some woods and the body of his mother, Yoshiko A. Smith, 30, under storm debris early Wednesday.

Significant mix of snow, ice and sleet

The storm began its cross-country journey by dumping heavy snow in the Sierra Nevada.

Damage followed Tuesday when thunderstorms from the storm swept through Texas.

At least five people were injured In the Dallas suburb of Grapevine, police spokesperson Amanda McNew said.

Forecasters now expect the vast system to hobble the upper Midwest with ice, rain and snow for days and also move into the central Appalachians and Northeast.

The National Weather Service issued a winter storm watch from Wednesday night through Friday afternoon, depending on the timing of the storm.

Residents from West Virginia to Vermont were told to watch for a possible significant mix of snow, ice and sleet.

"This system is notable for the fact that it's going impact areas all the way from California to eventually the Northeast," said meteorologist Frank Pereira with the National Weather Service in College Park, Maryland.