Frigid air that normally stays trapped in the Arctic has escaped, plunging deep into the United States for an extended visit that is expected to provoke teeth-chattering but not be record-shattering.It’s a cold air outbreak that some experts say is happening more frequently, and paradoxically, because of a warming world. Such cold air blasts have become known as the polar vortex. It’s a long-established weather term that’s become mainstream as its technical meaning changed a bit on the way.What it really means to average Americans in areas where the cold air comes: brrrrr. What’s happening is the jet stream — that usually west-to-east river of air way above ground that moves weather systems along — has made a roller-coaster like dip from the Pacific Northwest to the Southeast and is stuck on that wavy track. To the west of that plunge, in California, it’s hot and dry. But to the east and just above the dip, it’s a taste of the North Pole.“We’re just getting a lot of cold Canadian and Arctic air that’s being just channeled from north to south,” said Dan DePodwin, AccuWeather director of forecast operations. “We really expect this to be more of a prolonged stretch of well below historical average temperatures. We’re talking 12 to 25 degrees Fahrenheit (7 to 14 degrees Celsius) across a large portion of the eastern half of the country.”RELATED COVERAGE
The worst will be in areas that just got hit with heavy snow, from Kansas to Washington, said National Weather Service Weather Prediction Center meteorologist Zack Taylor: “That’s where we could see actual overnight lows down well into the single digits, perhaps even below zero in some places across the Ohio Valley and the Plains.”Workers clear steps at the Capitol in Washington, Monday, Jan. 6, 2025. (AP Photo/J. Scott Applewhite, File)
Judah Cohen, seasonal forecast director at the private firm Atmospheric and Environmental Research, called this a polar vortex event. He and DePodwin called it a stretching of the polar vortex, which is cold air normally penned in high above the Arctic that’s there year round.“Think of it as like a rubber band at rest, kind of roundish,” Cohen said. “If you start pulling on it, it gets elongated like a hot dog or like pulling on a rubber band. It gets stretched out.”When the polar vortex stretches it can either bring that cold air south to the United States or toward Asia, said Cohen, an expert in winter weather. Other times, when something called sudden stratospheric warming happens, the polar vortex moves away from the Arctic and comes south or even splits. That’s not the case this time, Cohen said.Other meteorologists, including Yale Climate Connections’ Jeff Masters, along with National Weather Service Climate Prediction Center meteorologist Laura Ciasto, who co-writes the agency’s “polar vortex blog, ” say the polar vortex term is being misused. Technically, the polar vortex