The Polar Vortex Is Returning This Weekend

NBC News reports:

Millions of Americans across the Northeast should brace for what could be the coldest temperatures in over a decade this Valentine’s Day weekend, forecasters warned Friday. The National Weather Service said the “life threatening” icy blast was set to arrive in the region Saturday, but the coldest air would not arrive until Sunday morning — with several cities facing the prospect of subzero temperatures.

Wind chills are expected to plummet 20 to 40 degrees below zero across the region, with the National Weather Service issuing a patchwork of wind-chill warnings and watches. It said conditions “will result in frostbite and lead to hypothermia or death if precautions are not taken.”

The forecast cold air is the product of a weather system called the polar vortex, a large cyclone that sits above the North Pole all year round. The bitter temperatures expected across the Northeast are being brought by a “piece” of this vortex that has broken off and traveled further south, Palmer said.