Polar Vortex 3-Way Split: What Fracture Means In Missouri

ST. LOUIS, MO — The polar vortex, that punishing blast of cold air that blows in straight from the Arctic, has fractured, and it’s going to make for hideously cold temperatures in much of the United States, including Missouri.

In our state, the National Weather Service says we’re in for a brutal few weeks, with temperatures plummeting well below average for this time of year. We can also expect another winter storm this weekend, though it shouldn’t be quite as severe as last weekend’s. St. Louis will likely see 2- to 3-inches of snow and strong winds.

Some forecast models call for temperatures 25 degrees or colder than normal by the end of the weekend in the central and eastern U.S. The blast of Arctic air should arrive in the Midwest just in time for Sunday night’s AFC Championship Game between the Kansas City Chiefs and New England Patriots. The National Weather Service predicts temperatures of 6 degrees at kickoff time in Kansas City, with a wind chill of about 3 below zero.

But don’t think you can pack up your parkas, facemasks and other gear and be done with bone-chilling temperatures. Forecast models are suggesting the brutal, Arctic cold could hang around well into February, bringing an end to what has been a mild winter so far in many parts of the United States.

The polar vortex, a whirlpool of dense, frigid air over the Arctic that looks like a large tornado, is always around in the winter, but in some years it remains parked in the stratosphere where it belongs through the winter months and then dissipates in the spring. But in other years, warm air makes its way north and heat things up in what’s called “sudden stratospheric warming” — temperatures in this part of the atmosphere can increase by as much as 90 degrees in a matter of a few days.

When that happens, the vortex either moves south or it splits, as it did this winter when the stratosphere over Siberia suddenly warmed in early December. The three-way split, or fracture, suggests “severe and punishing” weather and “heightened storminess,” according to a weather model forecasts cited by The Washington Post.

The Weather Channel said the polar vortex has split into three distinct circulation areas — hurling frigid air south toward Russia, Europe, Canada and the United States. Other meteorologists suggested it’s a two-way split.

Either way, predicting what a fractured polar vortex means for a specific area is complicated and such events always come with big expectations, Amy Butler, an atmospheric scientist at the Boulder, Colorado-based Cooperative Institute for Research in Environmental Sciences, told Popular Science.

“People will always be like OK, it’s happened, I want to know when it’s going to get cold in New York,” she said. “We can say your chances of it being cold in this region have now increased … But we don’t know for sure when it’s going to snow.”

“A big factor is just random variability,” William Seviour, an atmospheric scientist at the University of Bristol in the United Kingdom, told the magazine.“The atmosphere is chaotic, which means there’s a limit to how much you can predict.”

Butler does expect the eastern two-thirds of the United States to begin feeling the effects of the polar vortex by the end of January, and it could last as long as six weeks, she said.

Weather observer Eric Webb, a University of North Carolina-Charlotte graduate who studies climate phenomena, has been watching polar vortex models. He tweeted temperatures that could hover around the 10-degree mark in central North Carolina, but “what’s coming at the tail end of January into February will be a lot more impressive.”

“This is about the coldest planetary-scale pattern you could ask for,” he said.

And Michael Ventrice, a meteorological scientist for The Weather Company, noted that forecasting models for the United States and Europe are in agreement in their 14-day outlooks. “Wow,” Ventrice tweeted. “This is going to be a wild, wild wintry ride for the eastern U.S. and Europe during the end of January.”

Image via National Weather Service