Dozens of bodies filled the refrigerator at the Cook County medical examiner’s office, and the staff ran out of gurneys for the ones that followed in the next hot hours.
Soon after Dr. Edmund Donoghue stepped into the office on the hot morning of July 15, 1995, bodies would be waiting in the hallways.
Donoghue, the chief medical examiner for Cook County, had been told the night before of investigations into 40 new deaths, most thought to be heat-related. The county record for medical examiner investigations in a single day–any day–was 37.
But there were 87 newly discovered bodies that morning. And the phones kept ringing as more bodies were found in the roasting city.
“It was kind of like a warm moist cloud passed over the city of Chicago and left all of these deaths in its wake,” Donoghue said. “It was clear on Saturday that we were having a heat disaster.”
When Donoghue told Dr. John Wilhelm, then at the Chicago Department of Public Health, about the volume of cases arriving at the examiner’s office, most elderly victims, Wilhelm remembers asking if an explosion had taken out a city block.
Next, he wondered why nobody had been checking on those people.
Ten years ago this week, Chicago was gripped in a deadly heat wave that would kill more than 700 area residents, changing how the city reacts to emergencies and establishing a benchmark for the perils of facing hot weather unprepared.
A decade later, cities around the world have adopted new heat wave warning systems, all drawing, in some part, on the lessons learned in Chicago in 1995, when the heat had been predicted but its lethality was unexpected.
Interviews with key figures who investigated Chicago’s deaths in 1995, as well as reviews of court records and historical weather data, form a picture of heat with an unprecedented ability to kill. And it shows how the understanding of heat’s ability to kill advanced during those blistering weeks.
For days, hot, high atmospheric pressure had been creeping across the Great Plaines.
As a matter of physics, air needs temperature differences to move it. Warm air rises best into cooler air. Masses of cold air next to masses of hot air drive winds; the closer the air masses, the faster the winds.
In Chicago and for hundreds of miles, the air had stopped moving. It was all hot.
At 3 p.m. Thursday, July 13, weather watcher Frank Wachowski walked to the weather equipment behind his Burbank bungalow near Midway Airport and read an astonishing number–106 degrees, a Chicago area record.
“It felt like an inferno of hell,” he said. “Like a furnace.”
Humidity trapped in the soil during the rainy spring erupted into the air, clinging in a sinister haze near the ground. The dew point–the temperature at which damp air forms water droplets and a measure of how much water is trapped in the air–shot from 60 degrees on July 12 to 76 degrees the next morning.
In less than a day, the air had become more typical of the Amazon River basin than the upper Midwest. Droplets formed on home windows as though they were greenhouses. Sweat drenched shirts and foreheads but refused to evaporate in the high humidity. The air grew still. By July 14, even the jet stream at 18,000 feet had slowed to barely a breath of wind.
In the atmosphere to the west, a low pressure system was driving a southwest wind into the stagnant air over Chicago. With nowhere to go, the breeze turned downward and piled into the earth, the downdrafts heating as they fell and compressed, stifling thunderstorms before they could rise and provide relief.
A killer had formed, but it took days to realize it.
First deaths
The first hint that the 1995 heat wave was a killer came from the back seat of a Ford Bronco driven by a day-care owner.
There was no air conditioning as she drove children back from the movies and lunch. At every stoplight, the children complained.
When they arrived at the 42-year-old mother’s home in the Roseland neighborhood, most of the 12 children fled the Bronco, dashing through scorching 100-degree temperatures for the central air conditioning in the one-story brick bungalow.
In court records, the worker said she locked the Bronco’s doors. She didn’t notice that two 3-year-olds were asleep in the back seat.
The report of their deaths–by an investigator who called Donoghue at home–rose the first red flags for the chief medical examiner, who was told reporters would likely be calling soon with questions.
“That’s the first time I realized,” Donoghue said. “In my mind they were the index cases, the first two deaths due to heat I was aware of.”
Every city can develop lethal heat, and one of the things researchers have learned since 1995 is that deadly conditions vary from city to city.
Though the heat wave that killed hundreds in the upper Midwest was the deadliest in recent memory, it came on the heels of another heat wave in Philadelphia that contributed to the deaths of 118 people and prompted a move to develop some mechanism to prevent future heat deaths.
The result was a test program put in place by Larry Kalkstein, senior research fellow at the University of Delaware Center for Climatic Research.
As Chicago dealt with its own killer heat in 1995, Philadelphia was already starting to see the benefits of having a hot weather warning system.
“Nobody can tell if it was because of the system or whether it was just luck, but certainly many less people died in Philadelphia than in Chicago that summer, and the heat was almost as bad,” Kalkstein said.
During that time, the National Center for Environmental Health also studied the factors that led to the Chicago area’s heat-related deaths in 1995, while the National Oceanic and Atmospheric Administration studied Chicago’s killer weather system and the city’s response.
The contrast between Philadelphia’s and Chicago’s experiences in 1995 soon fed a push to expand hot weather warning systems nationwide.
In 1997, Kalkstein’s system in Philadelphia was so promising that the National Weather Service took it over and expanded it to 15 other cities including Washington D.C., New Orleans, Cincinnati, and Dallas.
In Chicago it has been added to the heat emergency plan the city established months after the 1995 heat disaster.
“We can refer to those events like Chicago and say that could happen to any northern city that isn’t used to heat events and are not prepared,” said Mark Tew, who leads the weather service’s Public Weather Warning Program.
Driving the program’s acceptance is that it is built around the fact that no two urban areas react the same way to heat, said Kalkstein.
His warning model is based on several factors, he said, but ultimately boils down to one:
Determining which of a city’s weather patterns results in death.
In the weeks after Chicago dealt with its heat wave, Paul Dailey, then chief of the National Weather Service’s Chicago office, came to the same realization.
“We sat down and tried to figure out what we could do,” said Dailey, one of the panelists on a commission established by Mayor Richard Daley. “Our perception of heat waves in the past was completely out of whack–we always saw them as a nuisance. I don’t think any of us dreamed of what really could happen.”
Alarming forecast
In the days leading up to the mid-July heat wave, forecast temperatures had been on the money, and Dailey’s office had put out both heat and weather advisories.
But it clearly wasn’t enough. People don’t react to advisories, but they do react to warnings. Whom to warn was the next step.
Donoghue produced a list of Cook County’s summer death records back to 1979. With the city’s average daily summer death rate of 72 people in mind, Dailey hunted for days on which 100 people or more had died. He found 25. Then he turned to the weather records for those days.
“Lo and behold,” he said, “it was right there. You could link up days when we had extreme heat and temperatures where it didn’t cool down.”
The implication was obvious.
“I could have put out a warning to those people that said we have heat coming here that’s going to kill people,” he said.
In the report that followed, the panel laid out Chicago’s killer weather scenarios: Three days in a row of maximum heat indexes between 100 and 105 degrees, mostly sunny skies on at least two of those days, or nights that never cooled down below 75 degrees.
Also deadly could be two days in a row with heat indexes between 105 and 110 degrees, or even a single day with a heat index over 110 degrees.
Other changes would come from Chicago’s experience, among them a standard definition of what constitutes a heat-related death.
“This was quite a lesson, not just for Chicago, but for many cities,” Wilhelm said. “The lesson is how isolated people can become in a metropolitan area.”
Since the system has been in place–albeit during a period of more mild summers–Chicago’s heat-related deaths have been in decline in recent years.
During the hottest summer since 1995–1999–there were 117 deaths blamed on excess heat. For other years in the last decade, the number of heat deaths ranged from 42 in 2002 to two in 2004.
“I think it has worked,” said Dailey, who retired from the weather service in 2002. “If you can see it coming–and we can, with great accuracy–you can warn people.”
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Many layers led to 1995 heat wave
Unusual meteorological conditions trapped the Midwest and Chicago in a mass of hot and humid air that contributed to hundreds of deaths by the summer’s end.
Unique meteorological conditions conspired
Jet stream: Strong jet stream winds with potential to cause thunderstorms were diverted north.
Humid tropical air: Strong surface winds prevented Lake Michigan breezes from cooling Chicago.
Dew points (July 13, 1995)
Dew points, a measure of moisture in the air, were very high, making it hard for people’s bodies to cool. Also, because moisture holds onto and reradiates heat, nighttime cooling was seriously reduced.
A bubble of warm air was stifling
1. Sun heats the ground and surrounding air. July sunlight is among a year’s strongest, nearly five times stronger than in December.
2. The heat dome prevented the low, hot air from rising. The dome of air that sits over the area usually is cool, which allows the warm air to rise.
3. The heat dome prevented rain clouds from forming and tempering the heat.
Heat-related deaths
In Cook County
July 1995
JULY 12: 0
JULY 13: 4
JULY 14: 51
JULY 15: 214
JULY 16: 129
JULY 17: 95
JULY 18: 41
JULY 19: 14
JULY 20: 11
JULY 21: 4
JULY 22: 1
JULY 23: 3
JULY 24: 5
JULY 25: 4
JULY 26: 2
JULY 27: 2
JULY 28: 2
JULY 29: 2
JULY 30: 0
JULY 31: 4
Definition of heat-related death
– Body temperature above 105 degrees
– High ambient temperature where body found
– High ambient temperature where deceased last seen alive before heat spell
Sources: WGN-TV’s Tom Skilling, National Weather Service, National Oceanic and Atmospheric Administration, City of Chicago, U.S. Department of Commerce
Chicago Tribune/Sue-Lyn Erbeck and Keith Claxton
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jjanega@tribune.com
