Meteorologists warn that the coldest burst of Arctic air this season is coming to put an icy and prolonged exclamation point on America’s winter of repeated polar vortex invasions starting this weeken

The latest arctic blast will move into the northern Rockies and northern Plains Saturday and spread to the central and eastern U.S. through much of next week.

The vortex is essentially an area of low pressure in the upper layers of the atmosphere over the polar region up north. This vortex consists of powerful westerly winds in the stratosphere, about 10 to 30 miles above the North Pole, according to Climate.gov.