Polar Vortex

How Cold Is It Really In America?
We have been pretty lucky so far this winter - since we don't live in the North East and haven't had to deal with a Polar Vortex! We haven't had sub-zero temperatures or even very many days of frosted windows. So how cold is it really in America?
What is a Polar Vortex?
While today's high is only 37, it is winter here in Twin Falls, but across much of the United States there is this crazy cold storm called a "polar vortex."  What is a polar vortex?  NBC explains: