NORFOLK, Va. >> The plunging polar vortex brought subfreezing temperatures Tuesday to some of the southernmost points of the U.S., threatening to dump snow on parts of Texas and Oklahoma in coming days and contributing to a power outage in Virginia’s capital that made the water unsafe to drink.

The arctic blast that descended on much of the U.S. east of the Rockies over the weekend has caused hundreds of car accidents, thousands of flight cancellations and delays, and led communities to set up warming shelters, including one at a roller rink and another in the Providence, Rhode Island City Council chambers.

As the cold front moved southward, it prompted a cold weather advisory for the Gulf Coast and pushed the low temperature in El Paso, along Texas’ border with Mexico, to 31 degrees, with an expected wind chill factor ranging from 0 to 15 degrees early today, according to the National Weather Service. Road crews in the Kansas City area, which received about 11 inches of snow in recent days, have struggled to keep up with clearing streets and highways.

“I don’t know what super powers some think snow removal teams have but 2 days of straight snow & ice isn’t going to disappear overnight,” the Unified Government of Wyandotte County and Kansas City, Kansas, wrote Monday on Facebook.

In frigid northern Virginia, Carol Grayson said Monday that she wished she had a metal shovel — not her plastic one — while trying to carve a path for her beagle, Rudy, and sheltie, Emma.

“We’re not used to it here, and we’re just not prepared,” Grayson 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. Some experts say such cold air outbreaks are happening more frequently, paradoxically, because of a warming world.

Southern discomfort

As points north and east dug out of snow and ice Tuesday, communities in Texas, Oklahoma and Arkansas were preparing for their own helping. A low-pressure system was expected to form as soon as today near South Texas, and could dump several inches of snow in the Dallas area and lower Mississippi Valley, the weather service said.

In Texas, crews treated the roads in the Dallas area amid forecasts of 1 to 3 inches of snow on Thursday, along with sleet and rain, said National Weather Service meteorologist Sam Shamburger. He said up to 5 inches of snow was expected farther north near the Oklahoma line.