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Questions mount in Naperville after tornado warning came after touchdown this past weekend, sirens didn't go off

Concerns after sirens failed to go off for tornado in Naperville
Concerns after sirens failed to go off for tornado in Naperville 03:10

ROMEOVILLE, Ill. (CBS) -- Concerns have been growing in Naperville after warning sirens were not activated ahead of a tornado that touched down there early Saturday morning.

CBS 2's Jackie Kostek dug in Tuesday to find out to who bears responsibility and what can be learned.

The two main players in this issue are the National Weather Service, which issues tornado watches and warnings, and the city of Naperville, which uses those watches and warnings to activate their air-raid siren system.

One thing is clear - everyone is grateful no one was injured in this tornado. But still, there is a lot to learn in the aftermath.

Cleanup began shortly after an EF-0 tornado touched down in south Naperville early Saturday morning - first near the White Eagle Golf Club, then near a shopping plaza on Route 59 and 95th Street.

But now, there are questions – not only why Naperville's 19 warning sirens did not go off, but also why the National Weather Service didn't issue a tornado warning before the tornado touched down.

Let's start with the timeline.

"At approximately 5:29 a.m., we had issued a severe thunderstorm warning that covered all of Naperville - so both DuPage and Will counties," said Meteorologist Brett Borchardt with the National Weather Service. "At about 5:40 a.m. is when a tornado touched down in Naperville - and the tornado warning was issued subsequently at about 5:47 a.m."

In other words, the tornado warning came after the tornado actually touched down.

"In this case, yeah, that is what happened," Borchardt said, "but we did have a severe thunderstorm warning in effect."

Borchardt said two meteorologists were actively monitoring severe weather Saturday morning. He said severe thunderstorm warnings are issued when wind speeds reach 58 mph or higher, and EF-0 tornadoes like the one in Naperville happen when wind speeds are between 65 and 85 mph.

There is a big difference, Borchardt said, between last Saturday's storm and the storm that produced an EF-3 tornado in the western suburbs on Father's Day of last year.

"Last year, the environment was conducive for those strong, long track tornadoes," Borchardt said. "This past Saturday morning, the environment and storm were capable of producing very short-lived and brief tornadoes, wind speeds that are typically seen in an average severe thunderstorm."

That is still dangerous, Borchardt said, but not necessarily more so than an average severe storm. While the City of Naperville isn't blaming the National Weather Service for the delayed warning - saying they understand the ever-changing nature of severe weather - they are "concerned" their sirens didn't go off when the tornado warning actually was issued at 5:47 a.m.

A city spokesperson says the system should automatically trigger when a warning is issued. They're now investigating why it didn't.

Both the National Weather Service and the City of Naperville say beyond the outdoor siren warnings, people should have other ways of being alerted to severe weather - including apps on your phone that will wake you up if storms roll through overnight or early in the morning. 

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