Why did I hear sirens if there was no tornado?

GRAND RAPIDS, Mich. (WOOD) — As a strong line of thunderstorms swept through West Michigan Tuesday morning, many reported hearing sirens — even though no tornadoes were reported.

Sirens sounded Tuesday in Kent, Ottawa and Allegan counties, authorities confirmed.

Though outdoor warning sirens are often referred to as tornado sirens, they aren’t always warning of tornadoes. According to the National Weather Service , a siren simply indicates that a life-threatening event is occurring, so you should head inside and learn more.

“(A siren) could be (used) for some type of safety threat, terrorism or a militaristic civil defense event. Maybe a chemical spill,” Matt Groesser, emergency management coordinator for Kent County, explained. “It could be a lot of different things. So sirens don’t tell you a lot of information other than something is going on and you need to seek further information.”

Guidelines for sounding sirens vary by jurisdiction.

“We have a policy here in Kent County where any sustained winds greater than 70 miles per hour, that’s something we’ll consider siren activation for,” Groesser told News 8.

The NWS says it’s becoming increasingly common for communities to use sirens to warn of threats like destructive wind and hail. Winds that exceed 70 mph can uproot trees, while golf ball-sized hail can break windows, according to the NWS. Both can be life-threatening for people who are outdoors.

Groesser says Kent County’s policy can be traced back to May 31, 1998, when a fast-moving line of severe thunderstorms known as a derecho blasted through. In Michigan, four people were killed, around 150 people were injured and thousands of homes and businesses were damaged.

“You can have just as much damage from straight-line winds as you can from a tornado,” Groesser said.

On Tuesday morning, the NWS reported 71 mph wind gusts in the Muskegon area, 70 mph gusts in Norton Shores and 68 mph gusts near Grand Rapids, in the Alpine area. Stony Lake in Oceana county also recorded 68 mph gusts, with 65 mph gusts at the Macatawa maritime station.

In addition, the NWS told News 8 that starting around 5:30 p.m. Monday, a technology outage prevented its ability to send an alert to smartphones. The NWS said it worked with Kent County Emergency Management to ensure people got a warning, and management opted to sound the sirens due to the wind speeds and the storm’s destructive nature.

Allison Farole, emergency management administrator for the city of Grand Rapids, said that Grand Rapids sent out emergency alerts but did not sound its sirens Tuesday morning.

“For the city’s policy, we only set them off for tornado warnings,” Farole told News 8. “But we also did not have winds over 70 mph in the city. I think they got up just a little over 65 mph, so it did not threshold either.”

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