The storm system that unleashed deadly tornadoes in the South maintains its wind threat and delivers snow to the eastern US

A storm system that spawned a series of deadly tornadoes in the Deep South threatens more damaging winds Tuesday across that region while disrupting travel in the Northeast with snow and ice.

A tornado watch is in effect until 7 p.m. ET for portions of southeast Georgia and northeastern Florida, according to the National Weather Service’s Storm Prediction Center.

Meanwhile, about 25 million people in portions of the Great Lakes region and Northeast are under winter weather advisories and warnings. Over 270 US flights have been canceled and there have been more than 3,300 delays across the country reported by Tuesday afternoon, many in Boston, where 3 to 4 inches of snow and sleet is predicted.

As the storm pushes east, a flash-flood threat continues in the Ohio Valley. About 8 million people are under a flood watch, warning or advisory as heavy rain falls in Kentucky, West Virginia, and southern Ohio and Pennsylvania. One to 3 inches of rain is expected.

Tornadoes still threaten the South

Tornado activity across the South is expected to give way to a straight-line-wind event in Alabama and Georgia, CNN meteorologist Michael Guy said. Destructive straight-line winds can peel off thunderstorms and leave long stretches of damage, rather than spinning around a vortex.

“The main threat is damaging winds, though a brief/spin-up tornado cannot be ruled out,” the weather service in Atlanta said.

A marginal risk of storms — level 1 on a scale of 5 — remains Tuesday over north Florida and the southeastern US coast, where a few strong to severe storms are forecast, CNN meteorologist Dave Hennen said. The risk is 2 of 5 in the area under the tornado watch.

In central Mississippi, one school district canceled classes due to the storms Monday night and because of the threat of more bad weather.

“Due to the inability to properly assess schools and roads tonight following the inclement weather, all schools in the Laurel School District will be closed,” the district said in a statement.

Twenty-seven tornadoes were reported Monday in Louisiana, Mississippi and Alabama. That tops the December average of 23 tornadoes, Hennen said.

Travel headaches begin further north

Farther north, snow is predicted — and winter weather alerts have been issued — from Indianapolis to Cincinnati and Columbus in Ohio and through to Pittsburgh, Hennen said.

To the east and north, Philadelphia and New York City are not in the advisory zone, but areas just west and north are included, and freezing rain is already making travel dangerous.

“Heavy snow and possible ice will continue to plague areas of the Ohio Valley to the Northeast and New England … through Tuesday,” the National Weather Service said.

Parts of the Northeast — including areas in New York and around Boston — may see up to 6 inches of snow by Wednesday, the weather service said.

At least 3 killed as tornadoes reported in the South

At least three people were killed Monday when more than two dozen tornadoes touched down across the Southeast, damaging homes, churches and other buildings, officials said.

A 59-year-old woman in Vernon, Louisiana, was killed when a tornado destroyed her mobile home, the Vernon Parish Sheriff’s Office said.

Roofs were blown off homes, and people were trapped in their houses, Beauregard Sheriff’s Office Chief Detective Jared Morton told CNN affiliate WJW. “A substantial number of trees and power lines” also were felled, the sheriff’s office said.

A couple was killed in Lawrence County, Alabama, when a tornado passed through, Town Creek Police Chief Jerry Garrett said.

A 7-year-old boy was found injured near the couple and taken to the hospital, Garrett said.

“I join the community of Town Creek in grieving the loss of a husband and wife,” Gov. Kay Ivey said Tuesday in a statement that urged community support for all affected. “While most of us slept through the storm, a family is waking up today devastated.”

More injuries were reported as a tornado tore through Columbia, Mississippi, the police chief said. Some officers ferried people to the emergency room, Columbia Police Chief Michael Kelly told CNN.

“We are just happy at this time that there are no fatalities reported,” he said Monday night.

In Edwards, Mississippi, residents were in the dark late Monday as storms trekked through the area.

“I heard glass scattering everywhere, trees falling. I’ve been here for 42 years. I’ve never experienced anything like this before,” Shelia Hilton told CNN affiliate WLBT.

In Lee County, farther north, about 60 homes and a church were damaged, said Paul Harkins, the 911 director for the county’s sheriff’s office. No one was in the church when the weather pushed through, said state Sen. Chad McMahan.

“We are blessed tonight,” Guntown, Mississippi, Mayor Bud Herring said of the lack of fatalities or serious injuries.