The Daily Parker

Politics, Weather, Photography, and the Dog

It's worse than that: he's dead cold, Jim

The forecast for Wednesday not only predicts the coldest day since 1996. Now meteorologists predict the coldest day ever recorded in Chicago:

Temperatures are forecast to inch up to a daytime high of about -26°C on Wednesday—the first subzero [Fahrenheit] high temperature in five years and the coldest winter high ever recorded in Chicago—before dipping, again, to about -29°C overnight. The coldest daytime high in Chicago was -24°C on Christmas Eve 1983.

For younger Chicagoans, the burst of Arctic air set to overtake the city this week could be one of the coldest days of their lives. For Generation Z, this week’s predicted low temperatures have only two rivals: -27°C on Jan. 6, 2014, and -28°C on Feb. 3, 1996.

Awesome. Note that I experienced all of those, and blogged about the 6 January 2014 weather right here. 

In no small irony, this cold snap seems directly related to global warming:

The wintry onslaught will be driven by the Northern Hemisphere’s polar vortex, the pocket of cold air sitting atop the North Pole. When temperatures rise in the Arctic, the polar jet stream — the torrent of westerly winds that hold the polar vortex in place — can weaken and dip into parts of North America.

“Occasionally this ring of winds deforms or even splits, which allows the cold air to spill southward over mid latitudes — this is exactly what’s happening now,” said Jennifer Francis, a senior research scientist with Woods Hole Research Center in Massachusetts, in an email. “It just so happens that the lobe of cold air is located over central North America, with Chicago in the crosshairs.”

A growing body of evidence suggests another warming trend in the Pacific Ocean is believed to be causing the jet stream that confines the polar vortex to warp further, with warm air penetrating near the Pacific Northwest and a lobe of cold air sinking into the Midwest and Northeast.

“The stronger ridge does two things: It pumps cold air into central North America, which deepens the downstream trough, and it also becomes more persistent because larger jet stream waves move more slowly than small ones,” Francis said. “This is partly why this jet stream pattern tends to be long-lived once it sets up.”

Whoo boy. Can't wait. Doggie daycare is closed, and Parker's regular dog walker isn't certain he can make it, so I'll be working from home.

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