Meteorologists had predicted that parts of the U.S. would experience the 10th and coldest polar vortex event this season. Weather forces in the Arctic are pushing chilly air that usually stays near the North Pole into the U.S. and Europe.

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 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.