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Tornado warnings herald weeklong heat wave in Chicago

Much of the Chicago area was under a tornado warning Monday night, as northeast Illinois prepared for a heat wave that could approach record highs for June.

CHICAGO (CN) — Much of the Chicagoland region is in the grips of a heat wave that isn't expected to break until Friday, the Illinois Climatologist's Office said Tuesday morning. And next week could see temperatures rising again.

"It's not great news, unfortunately," Illinois State Climatologist Trent Ford said.

The heat wave began on Monday as temperatures reached a high of 93 degrees Fahrenheit with a heat index of over 100. It was the hottest June 13 in Chicago since 2001, according to the National Weather Service, and was capped off with a supercell storm that prompted tornado warnings across much of northeast Illinois. No tornado touched down, but 84 mph wind gusts were recorded at O'Hare International Airport.

Thousands of people were left without power in the wake of the storm. As of 2 p.m. Tuesday, local energy utility Commonwealth Edison reported there were still more than 580 active outages in the Chicago area, affecting more than 20,000 people. The NWS didn't forecast any more storms in the region for the rest of the week, and Ford said the summer was shaping up to be a dry one. But he added that could change quickly.

"The thing about precipitation in the summer is you can have two or three days where it's dry, then you have a pop-up storm that dumps two or three inches of rain over an area, and now it's wetter than normal for the summer," Ford said.

Tuesday brought sunshine after the storm, but it was even hotter than Monday. By 2:30 p.m., temperatures recorded at the Midway Airport reached 99 degrees, with a heat index again over 100.

"It's now the second-hottest day on record for the date," Chicago NWS meteorologist Gino Izzi said. "The hottest [June 14] was in 1987."

While not yet the hottest week in June on record for Chicagoland - that was the week ending in June 25, 1988 - Ford said the temperature spike augured hotter-than-average conditions for the summer.

"At least for the short-term, we're looking at warmer-than-normal conditions for the rest of June into July," Ford said. "It doesn't bode well for people who don't like heat."

"Normal" and "average" temperatures are difficult things to define in the age of global warming. Rather than a static metric for gauging the climate, Ford said that the U.S. Climate Prediction Center calculated average temperatures using a moving 30-year standard.

"At the end of each decade, the Climate Prediction Center takes the temperatures from the last three decades to calculate a 'normal' range," Ford said. "The current standard is 1991 to 2020."

A high-pressure system currently sitting over the east-central U.S. was driving high temperatures across the region, the Illinois State Climatologist's Office said on Tuesday, June 14, 2022. (Courthouse News screenshot from earth.nullschool.net data)

During that 30-year time period, the National Oceanic and Atmospheric Administration reported that the average temperature for the continental U.S. was 53.3 degrees. It was a half-degree increase from the 1981-2010 average of 52.8 degree and more than 3 degrees hotter than the average 50.2 degrees reported for the period of 1961-1990. The hotter temperatures, Ford said, has driven more frequent heat waves and made Illinois' weather in summer particularly unpredictable.

"What is normal this year may be lower than normal 10 years ago - though it probably isn't, with climate change," Ford said.

The current heat wave in Chicago is being driven by a high-pressure system moving east over the central U.S., enveloping most of Illinois as well as Iowa, Indiana, Wisconsin, Ohio, Kentucky, Missouri and Tennessee. Chicagoland's temperatures are expected to drop into the 70s on Friday, but Ford predicted it would only be a temporary reprieve before another high-pressure system moved in.

"We'll get breaks from these high-pressure systems [this summer], but they won't last more than a few days," he said.

To combat the heat, Chicago has established six public cooling centers, most of them on the city's lower-income South and West sides. The Chicago Department of Family & Support Services also encouraged people seeking to escape the heat to shelter in public libraries and park facilities.

Some people also escaped the heat Tuesday in public buildings such as City Hall and the Cook County Courthouse, citing a lack of space and pandemic safety concern at the cooling centers.

"No, I wouldn't [go to the cooling centers], I'm going to be right there in that building," one woman who asked not to be named said, sitting on a shaded public bench outside the courthouse while pointing to the adjacent City Hall. "With the pandemic now, you never know."

Extreme heat is the most deadly weather hazard to affect the U.S., according to the NWS. It reported that since 1992, heat has killed an average 158 people annually across the country. That's as many people killed by tornados and floods, the next deadliest weather hazards, combined. The heat poses an existential threat to people experiencing homelessness, as well as to seniors, young children and those without air conditioning or who are working outdoors.

Outside the courthouse, the woman said six cooling centers weren't sufficient to address such dangerous weather, particularly as they are only open 9 a.m. to 5 p.m. on weekdays. She alluded to July 2020 and other past heat waves, during which the city has also designated public buses as impromptu cooling spaces.

"They need to have cooling buses out here for people that need them," she said, gesturing around the courthouse plaza.

The city's Department of Family & Support Services did not respond to questions about whether it planned to open those cooling buses again this week.

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