The polar vortex, which is currently bringing the coldest temperatures in decades to the U.S., is a whirling and persistent large area of low pressure, found typically over both North and South poles. The northern polar vortex was pushing southward over western Wisconsin and eastern Minnesota on Monday, Jan. 6, 2014, and was bringing frigid temperatures to half of the continental United States. It is expected to move northward back over Canada toward the end of the week.
This image was captured by NOAA's GOES-East satellite on Jan. 6, 2014, at 11:01 a.m. EST (1601 UTC). A frontal system that brought rain to the coast is draped from north to south along the U.S. East Coast. Behind the front lies the clearer skies of bitter cold air associated with the polar vortex.