Schools in Chicago will remain closed Tuesday, as temps are expected to climb to a whopping +5°F during the day, the Chicago Tribune reports. Still, this is the longest subzero period in several years in the Windy City, climatecentral.org reports:
Chicago is anticipating its longest stretch of consecutive hours with below zero degree temperatures since February 1996 when the city endured 66 straight hours of below-zero temps. Chicago’s record is 98 hours, which occurred in December 1983. Luckily for winter-weary Chicago residents, that record is not likely to be reached or exceeded.
Record or not, it’s still unbearably, dangerously cold—so cold, in fact, that officials in Minnesota issued what they called a “Particularly Dangerous Situation” warning about the “historic and life-threatening cold.” They got that right! And I’m pretty sure that’s the official term, too.
The weather phenomenon causing the bitter cold across the Midwest is known as a polar vortex. It’s not hard to understand how it works. Basically, high-power cyclones of extremely low barometric pressure develop over the poles in winter. On occasion, the low gets loose and the cold air inside it escapes. Sometimes it dips into the southern US, as is happening now, shown on this temperature map:
Chicagoans have adopted the hashtag #Chiberia to refer to this polar vortex, even though the air doesn’t necessarily originate in Siberia. But whatever you call it, the pressure differential this time will bring wind chills near –50°F. The pressure differential, like the one that might occur Tuesday, is illustrated on the isobar map, here, from the Hydrometeorological Prediction Center at the National Oceanic and Atmospheric Administration for Oct 13, 2006.
The cyclones that occur over the poles during the winter are similar in structure and force to hurricanes that originate in the tropics. Except the wind chills from the polar vortex can cause frostbite on exposed skin in a matter of five minutes. Don’t take any chances outside!
The risk of death is even greater for people in thousands of homes in the Midwest that are still without electricity: More than 15,000 customers in Indiana, 6,800 in Illinois, and 2,200 in Missouri didn’t have power overnight Sunday, according to utility companies, CNN reported.