Chicago Weather

What is Causing Chicago's Recent Cold Snap? Here's the Atmospheric Phenomenon to Blame

Temperatures in southern Canada and the northern U.S. could be even colder than the North Pole because of a phenomenon known as "sudden stratospheric warming"

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Temperatures in Illinois have been downright frigid in recent days, and a phenomenon occurring at the North Pole is to blame for the recent cold snap.

According to Joey and Brant Miller of the NBC 5 Storm Team, the culprit behind the recent bone-chilling temperatures is a phenomenon known as “sudden stratospheric warming,” which is occurring over the North Pole.

During the winter, a mass of cold air forms over the North Pole and the Arctic Circle because of the fact that no sunlight shines on that area during the winter months. A stream of air called the “polar night jet stream” keeps that cold air in place, in what amounts to a large circle of air over the top of the globe.

When “sudden stratospheric warming” occurs, the potential exists for that “polar night jet stream” to be disrupted in a big way, and that is what is happening right now.

Our normal polar jet stream, the iconic image of sweeping air that you see in every weather report on your daily newscast, has a large ridge in the western portion of North America, which is caused by the jet stream hitting a large land mass. That ridge can extend all the way up the western Canadian coast and into Alaska, and as the “polar night jet stream” is pressed outward by stratospheric warming, it can conflict with that other jet stream, causing a “wobbling” effect.

When that “wobbling” occurs, it can spell trouble for parts of Canada and the northern United States. The warmer air in the stratosphere presses down on the colder air underneath it, sending it spreading out like toothpaste being squeezed from a tube.

As a result, Canada and the northern United States are seeing colder temperatures than what are being recorded at the North Pole.

The next question, of course, is how long it will take for that phenomenon to conclude, and there is more bad news on that front for cold-weather haters. To borrow another lesson from science class, cold air is more dense than warm air, and as a result, it takes something extremely big, whether it is a change in the jet stream or a large storm system, to dislodge the cold air.

Unfortunately for the Chicago area, nothing like that is in the immediate forecast, and it is unclear when the jet streams to return to a more normal state of affairs, meaning that we could be in for an even longer cold spell.

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