Tens of millions of people across two-thirds of the United States on Monday made last-minute preparations for an unusual blast of Arctic weather that is forecast to send temperatures plunging to their coldest in 20 years. The northeastern United States and parts of Canada have endured heavy snow and deadly cold conditions for a week, but the Arctic freeze now is moving through the central United States and threatening usually warm areas further south like Tennessee and Alabama. The wind chill from the rare "polar vortex" could make it feel as cold as -51 Celsius in places, weather forecasters say, prompting authorities in several towns and cities to issue warnings that people should stay indoors. Exposed skin could suffer frostbite in as little as five minutes in such conditions, experts say. "The coldest temperatures in almost two decades will spread into the northern and central U.S. today behind an Arctic cold front," the National Weather Service (NWS) said Monday. "Combined with gusty winds, these temperatures will result in life-threatening wind-chill values as low as [-51] degrees below zero. Also, heavy snow will develop from the eastern plains to the great lakes today, with up to [30 centimeters] of accumulation possible." The extreme weather prompted school cancellations Monday in several major school districts, including Saint Louis, Chicago, Detroit, Indianapolis, and Milwaukee. Even more school closures are expected Tuesday, when temperatures fall farther and Arctic weather hits the eastern United States.
