The polar vortex brings its bitter cold to the Southern US

The plunging polar vortex is bringing subfreezing temperatures to some of the southernmost points of the U.S. A forming storm system threatens to dump snow on parts of Texas and Oklahoma, while communities in Louisiana and Florida may see frigid cold. 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 forced school closures in some states. 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.