By PATRICK WHITTLE and BRIAN WITTE, Associated Press

ANNAPOLIS, Md. (AP) — The next round of bitter cold was set to envelop the southern U.S. on Tuesday, after the first significant winter storm of the year blasted a huge swath of the country with ice, snow and wind.

The immense storm system brought disruption even to areas of the country that usually escape winter’s wrath, downing trees in some Southern states, threatening a freeze in Florida and causing people in Dallas to dig deep into their wardrobes for hats and gloves.

On Tuesday morning, the wind chill temperature was 16 at Dallas/Fort Worth International Airport, according to the National Weather Service. A low-pressure system was expected to form as soon as Wednesday near south Texas, bringing the potential of snow to parts of the state that include Dallas, as well as to Oklahoma, Arkansas and Louisiana.

“As we go through the next few days, we’re still going to be seeing those colder-than-normal temperatures,” said Peter Mullinax, a meteorologist with the weather service in College Park, Maryland. “We’re going to see areas of snow and ice start to take shape across northern Texas, southern Oklahoma as we get into Thursday morning.”

Snow and ice are expected to make their way farther south into the lower Mississippi Valley, some of it “pretty disruptive,” he said.

Lingering snow and ice in the central Plains through the Ohio Valley into the Atlantic is likely to stick around for a few days, Mullinax said. That will create opportunities for constant re-freezing, and black ice, which may create treacherous travel conditions in some areas for the next few days.

The polar vortex that dipped south over the weekend kept much of the country east of the Rockies in its frigid grip Monday, making many roads treacherous, forcing school closures, and causing widespread power outages and flight cancellations. Some experts say such cold air outbreaks are happening more frequently, paradoxically, because of a warming world.

Ice and snow blanketed major roads in Kansas, western Nebraska and parts of Indiana, where the National Guard was activated to help stranded motorists. The weather service issued winter storm warnings for Kansas and Missouri, where blizzard conditions brought wind gusts of up to 45 mph. The warnings extended to New Jersey into early Tuesday.

A Kentucky truck stop was jammed with big rigs forced off an icy and snow-covered Interstate 75 on Monday just outside Cincinnati. A long haul driver from Los Angeles carrying a load of rugs to Georgia, Michael Taylor said he saw numerous cars and trucks stuck in ditches and was dealing with icy windshield wipers before he pulled off the interstate.

“It was too dangerous. I didn’t want to kill myself or anyone else,” he said.

The polar vortex of ultra-cold air usually spins around the North Pole, but it sometimes plunges south into the U.S., Europe and Asia. Studies show that a fast-warming Arctic is partly to blame for the increasing frequency of the polar vortex extending its grip.

Temperatures plunge across the country

The eastern two-thirds of the U.S. dealt with bone-chilling cold and wind chills Monday, with temperatures in some areas far below normal.

A cold weather advisory will take effect early Tuesday across the Gulf Coast. In Texas’ capital of Austin and surrounding cities, wind chills could drop as low as 15 degrees.

The Northeast was expected to get several cold days.

Transportation has been tricky

Hundreds of car accidents were reported in Virginia, Indiana, Kansas and Kentucky, where a state trooper was treated for non-life-threatening injuries after his patrol car was hit.

Virginia State Police responded to at least 430 crashes Sunday and Monday, including one that was fatal. Police said other weather-related fatal accidents occurred Sunday near Charleston, West Virginia, and Monday in Winston-Salem, North Carolina. Kansas saw two deadly crashes over the weekend.

More than 2,300 flights were canceled and at least 9,100 more were delayed nationwide as of Monday night, according to tracking platform FlightAware. Ronald Reagan Washington National Airport reported that about 58% of arrivals and 70% of departures had been canceled. The airport announced early Tuesday that it had reopened all runways after closing them Monday evening so airport crews could focus on snow removal and prevent refreezing on the airfield.

A record 8 inches of snow fell Sunday at the Cincinnati/Northern Kentucky International Airport, leading to dozens of flight cancellations that lingered into Monday. About 4 inches fell Monday across the Cincinnati area, where car and truck crashes shut at least two major routes leading into downtown.

More snow and ice are expected

In Indiana, snow covered stretches of Interstate 64, Interstate 69 and U.S. Route 41, leading authorities to plead with people to stay home.

“It’s snowing so hard, the snow plows go through and then within a half hour the roadways are completely covered again,” State Police Sgt. Todd Ringle said.

The Mid-Atlantic region had been forecast to get another 6 to 12 inches of snow on Monday. Dangerously cold temperatures were expected to follow, with nighttime lows falling into the single digits through the middle of the week across the Central Plains and into the Mississippi and Ohio valleys.

In North Texas, 2 to 5 inches of snow was expected beginning Thursday, according to the weather service. Snow could also hit Oklahoma and Arkansas, with some parts potentially getting more than 4 inches.

Classes canceled in several states

School closings were widespread, with districts in Indiana, Virginia, Kentucky, Missouri and Kansas canceling or delaying the start of classes Monday. Among them was Kentucky’s Jefferson County Public Schools, which canceled classes and other school activities for its nearly 100,000 students.

Classes were also canceled in Maryland, where Gov. Wes Moore declared a state of emergency Sunday and announced that state government offices would also be closed Monday. Government offices also were closed Monday in Kentucky, where Gov. Andy Beshear declared a state of emergency.

Tens of thousands are without power

Many were in the dark as temperatures plunged. More than 218,000 customers were without power Monday night across Kentucky, Indiana, Virginia, West Virginia, Illinois, Missouri and North Carolina, according to electric utility tracking website PowerOutage.us.

In Virginia’s capital city, a power outage caused a temporary malfunction in the water system, officials said Monday afternoon. Richmond officials asked those in the city of more than 200,000 people to refrain from drinking tap water or washing dishes without boiling the water first. The city also asked people to conserve their water, such as by taking shorter showers.

City officials said they were working nonstop to bring the system back online.

Whittle reported from Portland, Maine. Associated Press journalists Bruce Schreiner in Shelbyville, Kentucky; Dylan Lovan in Louisville, Kentucky; Ben Finley in Norfolk, Virginia; Lea Skene in Baltimore; Kathy McCormack in Concord, New Hampshire; Julie Walker in New York; Sophia Tareen in Chicago; Kimberly Chandler in Montgomery, Alabama; Zeke Miller in Washington, D.C.; John Raby in Charleston, West Virginia; Summer Ballentine in Columbia, Missouri; and Hallie Golden in Seattle contributed.

Read more of the AP’s climate coverage at http://www.apnews.com/climate-and-environment