Sirens didn't go off for St. Louis tornado — what are the activation rules in Chicago, suburbs?

CBS News

21-05-2025

The head of the City Emergency Management Agency in St. Louis has now been placed on paid leave, as an investigation has been launched into why the city's tornado warning system was not activated before a deadly tornado ripped through the area this past Friday.
Five people were killed and dozens of others were injured by the EF-3 twister, which hit parts of Central West End and North City in St. Louis.
St. Louis Mayor Cara Spencer said CEMA Commissioner Sara Russell was not in the office when the storms hit, so she was unable to push the button that triggers the sirens.
That got CBS News Chicago wondering about the siren protocol in Chicago and the suburbs, and who is in charge of activating the air-raid sirens in those places. The answer is that it depends on where one is — the policy and plan are different in Chicago than they are in Naperville, for example.
Sometimes, the sirens are automatically triggered by the National Weather Service. Other times, they are manually turned on, and a person is relied upon to press the button.
In St. Louis — where someone also has to push an alert button — Mayor Cara Spencer explained a "failure in protocol," because it was not clear whose role it was to do so. She took the responsibility away from CEMA Commissioner Russell.
"And we now have somebody form the fire department located at CEMA 24 hours a day to push that button, should we need it, while we ensure that the fire department can activate that system flawlessly moving forward. We will be conducting additional tests today at noon to ensure that the system is working."
The National Weather Service issues the tornado warnings that warrant siren activation.
"Ideally, goal-wise, these warnings are going to give 10 minutes-plus of lead time," said Ricky Castro, a meteorologist with the National Weather Service.
Castro explained that while the NWS issues tornado warnings, it is up to local governments whether or not they need the alerts, and how they distribute the information. In other words, the National Weather Service does not set off warning sirens, though not everyone understands that.
"We're not the ones in charge of that," Castro said. "We get social media comments. We'll get sometimes emails, phone calls, 'Why did this siren go off?'"
In places like Naperville, where an EF3 tornado touched down in 2021, the 26 outdoor warning sirens are activated automatically when the National Weather Service issues a warning.
In Chicago, the air-raid sirens only go off when the city's Office of Emergency Management and Communications turns them on. There are 112 sirens standing one to two miles apart, and they can be activated one-by-one, by siren zone — of which there are 12 — or citywide.
"It requires a fast decision-making process, and ideally as well, people will kind of know their safety plan in advance," Castro said.
Other Chicago suburbs' siren activation protocols are as follows:
Plainfield has 12 outdoor warning sirens activated manually by digital radio system. They can be activated through the village dispatch center upon direction of authorized village personnel, or though the Plainfield Emergency Management Agency.
Arlington Heights also has 12 outdoor warning sirens. They are activated by Northwest Central Dispatch, using a controller that can activate individual communities or the whole village. While the sirens are activated manually now, the village is working with its vendor to have the sirens activated automatically when a warning is issued.
Aurora has 20 sirens, with two more being installed. They are activated manually by the emergency department team, or by a 24-hour warning point at the 911 Public Safety Answering Plant.
Oak Brook has five sirens, the fifth of which waws added recently. The sirens are activated automatically using the Commander One alerting system from Federal Signal, which also manufactures many sirens. With Commander One, if the NWS issues a tornado warning, and the warning area touches or falls within the village border, all five sirens are activated right away.