The North Pole has unleashed "a large pool of Arctic air" that’s headed straight to the U.S., setting the stage for "record cold temperatures and dangerously cold wind chills," warns the National Weather Service in a new report.

The term “polar vortex” usually refers to the gigantic circular upper air weather pattern in the Arctic region. It is a normal pattern that is stronger in the winter and keeps some of the coldest weather bottled up near the North Pole.

The latest blast of frigid air will linger across the central and eastern U.S. through much of the week while another winter storm will dump heavy snow from the Rockies to souther Appalachians.

A lobe of the polar vortex, a ring of freezing air typically found near the North Pole, will once again move into the central and eastern states this week, bringing some of the coldest air of the winter season so far — and even helping fuel yet another winter storm in coming days.

BISMARCK, N.D. (AP) — Harsh weather moved west on Monday as a polar vortex was expected to grip the Rockies and the northern Plains after winter storms pummeled the eastern U.S. over the weekend, killing at least 10 people, including nine victims in Kentucky who died during flooding from heavy rains.

An Arctic blast tied in part to the polar vortex is driving record frigid air south from the Northern Plains toward the Gulf Coast Tuesday in a cold snap that will last the entire week. Threat level: This event is forecast to set records for the coldest temperatures on record for this late in the season,

Bitter cold has descended on swathes of the US this week, as the nation faces its 10th – and coldest – polar vortex of the season. In a normal winter, you can expect to see this happen two or three times.