Winter

The term “polar vortex” usually refers to the gigantic circular upper air weather pattern in the Arctic region, enveloping the North Pole. It is a normal pattern that is stronger in the winter and keeps some of the coldest weather bottled up near the North Pole. But at times some of the vortex can break off or move south, bringing unusually cold weather south and permitting warmer weather to creep up north. This week, parts of the U.S. are experiencing the 10th and coldest polar vortex event this season. Weather forces in the Arctic are combining to push the chilly air that usually stays near the North Pole into the U.S. and Europe.

BOSTON (AP) — Heavy snow is expected to blanket large portions of the Eastern U.S. while much of the country will endure dangerously cold temperatures in the coming days. Winter storm warnings issued by the National Weather Service are already in effect for parts of the Mid-Atlantic and will begin Sunday afternoon in New England. Up to a half-foot of snow is expected in areas from Maryland to Maine. That will be followed a blast of frigid air forecasted for the Rockies and Northern Plains into New England. The Gulf Coast and Southeast could see an unusual wintry mix of snow, sleet and freezing rain starting Monday in Texas.