Polar Vortex arrives but its 2nd wave may be even more brutal

Full story:
http://www.usatoday.com/story/weathe...torm/95420726/

The upper Midwest is in the deep freeze, with the arctic air expected
to shift eastward as the week wears on. The National Weather Service
posted advisories for the Dakotas and Minnesota, with wind chills from
10 to 20 below zero. (Dec. 13)

Thanks to another unwelcome visit from the Polar Vortex, dangerous,
life-threatening cold temperatures and fierce winds will spread across
much of the Midwest and Northeast over the next several days.

A snowstorm will also add to the wintry misery for parts of the northern
U.S. with blizzard conditions possible in some areas.

The cold will come in two waves, the first Wednesday and Thursday and
the second — which could be even more brutal — over the weekend.

Some locations could experience their coldest December temperatures in
several years, the Weather Channel said, and a few record lows may be
threatened.

The beleaguered northern Plains and Upper Midwest will again bear the
brunt of the icy onslaught: "Dangerous to life-threatening" wind chill
temperatures to 45 below zero are forecast Friday night through Sunday
morning in parts of the Dakotas, the National Weather Service said.

Wind chills this cold can cause frostbite in less than 10 minutes, the
weather service said.

The fierce cold is thanks to the Polar Vortex, which is seeping down
from its rightful place in the Arctic. Though the vortex has been around
for a few billion years and understood by scientists for several
decades, it only entered the popular lexicon as a synonym for miserably
cold weather a few years ago.