Vintage Chicago Tribune: Tornadoes!!! – Chicago Tribune

Today is the 55th anniversary of the deadliest tornado outbreak to hit our area, Chicago.

On April 21, 1967, at least 10 tornadoes touched down in northern Illinois. The most severe of these touched down in Belvidere, Oak Lawn and Lake Zurich. It was the worst such storm in the area’s history: 58 people were killed, including many children, and more than 1,000 were injured.

The lead of the front page story in the Chicago Tribune the next day captured the anguish of most Chicagoans: ”O, God, why did this happen.”

Trent Ford, Illinois state climatologist, told me the 1967 disaster “accounts for 60% of all April tornado-related deaths in Illinois between 1950 and 2020, and 25% of all tornado-related deaths in Illinois over that same time period, irrespective of month.”

Incredible, but that left me with more questions.

How did the tornado outbreak of 1967 happen? What conditions were in place that made the event so severe?

Ratzer: “In general, this was a ‘classic’ spring severe weather set-up. It was characterized by an area of low pressure moving northeast along a stationary front across eastern Iowa and northwest Illinois. A warm front extending east from the low was lifting north across northern Illinois, with warm/moist air along and south of the front providing the necessary moisture and instability needed for strong thunderstorm development. In the upper levels of the atmosphere, west-southwest wind in excess of 135 mph (jet stream level) and a mid-level disturbance moving across the upper Midwest contributed both large scale lifting of the atmosphere to aid storm development, but also deep vertical wind shear (winds increasing and turning with height). This wind shear, in turn, helped to produce what is known as ‘supercell’ thunderstorms, within which the entire storm updraft rotates which results in very strong storms which also tend to sustain themselves. These can often be tornado-producers across much of the Plains, Midwest and southeastern U.S. So the available instability (warm/moist air near the surface and cooler air aloft), and significant wind shear are what sets these type of tornado-producing storms apart from weaker storms.”

(To read more about this event, check out this synopsis from the National Weather Service.)

Were there any lessons learned from that specific event that help with severe weather prediction today?

Ratzer: “Yes. Major outbreaks such as the one in April 1967 are often catalysts for rapid advances in the science and methodology of forecasting and responding to such disasters:

• Some of these included the National Weather Service tornado watch and warning system (tornado “forecast” was changed to tornado “watch” in the wake of this outbreak).
• Outdoor Civil Defense sirens were repurposed for use as outdoor tornado warning sirens (Editor’s note: These are the ones you hear at 10 a.m. on the first Tuesday of each month). National Weather Service (It was the U.S. Weather Bureau in 1967) called for a greater emphasis on creating a severe weather spotter network, which eventually evolved into the modern-day SKYWARN organization with continual education for spotters, amateur radio operators and emergency managers.
• The National Weather Service also stressed the need for improved infrastructure, which led to the creation of the National Weather Wire Service (NOAA Weather Wire) which allows for quick dissemination of weather information and storm warnings to media and emergency managers.

“Of course, the state of the science of meteorology has progressed significantly over the past 55 years as well.

• We have significantly increased our understanding of thunderstorm development, evolution, the effects of near-storm environments and how tornadoes form.
• We’ve shifted from large county-based warnings to storm-based warnings, and conduct extensive forecaster training. Weather radar technology has advanced as well, with modern doppler radar (available for the National Weather Service in Chicago since the mid-1990s) able to actually detect rotation and strong winds within storms which was not possible with the equipment available in the 1960s.
• Higher resolution and more frequently available satellite imagery also helps us monitor storm development much more closely than the technology of the past.”

Is it typical for the Chicago area to experience tornadoes in April?

Ratzer: “Yes. Tornadoes can occur any time of the year, given the right combination of ingredients as outlined in my answer to your first question. Our tornado season in the Chicago peaks in the spring and early summer months. April, May and June are climatologically the months with the greatest number of tornadoes in the Chicago area.”

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— Kori Rumore, visual reporter

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Despite being known as the Windy City, Chicago has developed a false reputation as being impervious to tornadoes.

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While Oak Lawn and Belvidere were hardest hit on April 21, 1967, nearly the entire metro area felt the wrath of the twisters, from Evergreen Park and Palos Hills in the south, Stone Park and Geneva to the west, and Barrington and Lake Zurich to the north.

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Considered the deadliest single tornado in United States history, this estimated EF5 tornado produced winds of at least 200 mph. It touched down at 1:01 p.m. near Ellington, Mo., then remained on the ground for 219 miles through southern Illinois and southwest Indiana. “It was nearly dusk before it took its last savage blow,” the Tribune reported the next day. There were 695 deaths (at least 600 of those were in Illinois), more than 2,000 people injured and more than 15,000 homes destroyed, according to the National Weather Service.

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The EF5 tornado touched down outside Oswego about 3:15 p.m., striking Plainfield and roaring toward Joliet. Thirty minutes later, it was over. In all, 29 people were killed and at least 300 more injured, and 1,500 buildings were damaged or destroyed, according to the National Weather Service.

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Technological advancements, as well as improvements in communication that came in direct response to the 1990 Plainfield tragedy, make it unlikely that a tornado of this magnitude could ever occur again with so little warning, weather experts said.

But they said it shouldn’t have happened in the first place.

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