PHILADELPHIA (CBS) -- It's a term that first burst onto the scene during the brutal cold snap of early January 2014 - the Polar Vortex. Sounding like something from a high-tech action film, the Polar Vortex grabbed headlines as the temperatures plummeted below zero across much of the U.S.
In Philadelphia, the temperature dropped to four degrees with a wind chill of minus-18 during that cold outbreak.
But despite the flashy name, the Polar Vortex isn't a mystery -- in fact, it's always there; an area of persistent low pressure that sits over the arctic regions.
It's strongest in winter and weakest in summer, but it's always there.
When we refer to the Polar Vortex around here, what we're really referring to is a displacement of the Polar Vortex.
In somewhat inelegant terms, that is to say the circulation descends unusually far southward with the polar jet stream.
And that may be happening again next week, in a pattern that looks quite similar to that first Polar Vortex disruption five years ago.
A system will cross the Midwest Sunday into Monday and then arrive here on Tuesday with a mix of rain and snow.
That system will open the floodgates to brutal arctic cold, especially over the Northern Plains and Great Lakes regions, where air temperatures may hover around minus-30 with wind chills in the minus-50 range.
For us, the cold won't be quite as brutal but we can expect Wednesday through Friday of next week to feature temperatures roughly 15 to 20 degrees below average, with daytime highs no better than the low 20s and overnight lows in the single digits.
Wind chills may reach below zero, similar to the conditions we felt last Monday.
for more features.