polar vortex

What is the Polar Vortex?
It's Google's most searched term today, 'polar vortex.' So what is it, and more importantly, what is it not.  The National Weather Service took to social media to dispel some rumors.
Poiar vortex blasts US with frigid temperatures.
Old Man winter has packed a seriously cold punch lately.  A "polar vortex" of frigid, dense air has blasted much of the US with frigid, sub-zero temperatures and it's not over yet.   Central New Yorkers, we have a Wind Chill Warning in effect from midnight tonight un…