Software configuration error blamed for sirens not activating during July 23 tornado in Naperville – Chicago Tribune
Naperville’s outdoor warning sirens failed to automatically activate last month when an EF-0 tornado rolled through the city because the software managing the system wasn’t set up properly, a city emergency official said.
In a memo to City Manager Doug Krieger, Naperville Emergency Management Agency coordinator Dan Nelson said a configuration error during the April system setup was the reason the sirens did not activate July 23.
The vendor acknowledged the error, corrected it and is creating system-wide changes nationwide to ensure the automated system operates properly going forward.
Management agency staff will continue to review the incident and investigate ways to ensure citizens have accurate and timely warnings before potential severe weather hits, Nelson said.
The National Weather Service’s Romeoville office is responsible for severe weather warnings issued in the Naperville area and directly informs the public via weather radio, cable and television overrides, and phone alerts using the Federal Emergency Management Agency’s wireless emergency alerts, he said.
The agency also notifies the city through bulletins sent to the city’s 911 dispatch and emergency operations center.
Naperville’s policy is to activate the outdoor warning sirens when the city is included in a tornado warning issued by the weather service.
With the installation of the new equipment in April, the sirens were to be automatically activated through software provided by the outdoor warning system manufacturer when any part of the city falls within the geographic boundaries of the tornado warning area set by weather service, Nelson said.
The boundaries of the warning area trigger the alert, not the bulletin sent by the agency, he said.
However, emergency dispatch personnel can also manually sound the sirens if the bulletin specifically includes Naperville in the text description of the warning area.
Before April, the warning sirens could only be activated manually.
The National Weather Service confirmed an EF-0 tornado hit Naperville at 5:40 am July 23 and traveled southeast until 5:46 am
A tornado warning was issued at 5:47 am as the storm headed toward Romeoville.
Because the agency did not issue a tornado warning bulletin for the Naperville area before or during the tornado, Naperville’s sirens were not activated manually or automatically.
Nelson said the bulletin that was sent did not include Naperville in the description, and therefore city personnel were not alerted and did not manually activate the sirens.
However, the warning’s geographic boundaries drawn by the National Weather Service overlapped a small portion of south Naperville, which should have triggered the software that automatically activates Naperville’s outdoor warning sirens, he said.
When this did not happen, city staff immediately launched an investigation into why, he said.