There are two semi stationary areas where the polar vortex resides. One near Greenland and the other around northern Siberia
I saw a blog post from another meteorologist this week and it inspired me to write a short diatribe about the Polar Vortex that the national media has grabbed on as the ‘culprit’ for all the cold air. First the AMS Glossary of Meteorology:
A planetary-scale mid- to high-latitude circumpolar cyclonic circulation
, extending from the middle troposphere
to the stratosphere
. The Northern Hemisphere vortex
often features two centers—one near Baffin Island and the other over northeast Siberia—with analogous circumpolar asymmetry atypical in the Southern Hemisphere. The westerly airflow is largely a manifestation of the thermal wind
above the polar frontal zone
of middle and subpolar latitudes. The vortex is strongest during the winter in the upper troposphere and stratosphere when the pole-to-equator temperature
gradient is strongest. The stratosphere component of the circulation may be referred to separately as the “polar stratospheric vortex.” In summer, the strongest westerly circulation is largely confined to the troposphere, and the polar stratospheric vortex reverses in the upper stratosphere because of solar heating during the polar day.
Reference: Simmons, A., M. Hortal, G. Kelly, A. McNally, A. Untch, and S. Uppala, 2005: ECMWF analyses and forecasts of stratospheric winter polar vortex breakup: September 2002 in the Southern Hemisphere and related events. J. Atmos. Sci., 62, 668–689. 
Term Edited 30 January,2014
While this may be helpful let’s look at more of a layman’s definition found in Wikapedia:
A polar vortex is a persistent, large-scale cyclone that circles either of the planet’s geographical poles. On Earth, the base of the polar vortices are located in the middle and upper troposphere and extend into the stratosphere. They surround the polar highs and lie in the wake of the polar front. These cold-core low-pressure areas strengthen in the winter and weaken in the summer due to their dependence upon the temperature differential between the equator and the poles. …The Northern Hemisphere vortex often contains two low pressure centers, one near Baffin Island, Canada and the other over northeast Siberia.
So the AMS definition even goes so far to call it a ‘stratospheric’ ‘Polar Vortex’. This would indicate that it was more of an upper air circulation that does not reside on the surface. The other part of both definitions imply that the these circulations do not move. So why does the national media insist on calling every cold air outbreak a Polar Vortex? Representing cold air as the Polar Vortex is a misrepresentation of scientific knowledge that is fact. What I believe may have happened is that someone heard a description of the Polar Vortex spurning cold air, and that cold air travels through the northern hemisphere to the lower 48. Stating that the Polar Vortex is causing a cold air outbreak may be over simplifying what is a more complex scientific event.
The other problem is that these types of cold air outbreaks are not caused by a circulation like the Polar Vortex. Over simplifying of terms that sound sensational is a dangerous trap to get into to and probably not what most atmospheric scientists would agree to or condone.
So while the root cause may have something to do with the ‘core’ of the coldest air in the world it probably is not the single cause of this or any other extreme cold weather outbreak.