A cold air funnel hangs over western Webster City on Tuesday afternoon in this image shared by Lisa Westcott Schaa. It was taken from a position of West James Street.

At least one cold air funnel cloud caused concern Tuesday afternoon as a storm system moved through and Webster City’s sirens were activated.

Spotters reported seeing rotation in two places: near the water tower in the southwest area of the city and near 210th Street and White Fox Road on the city’s north side.

The National Weather Service did not issue a warning for tornadic activity, but the area experienced heavy rain and driving winds.

Instead, weather experts called it a cold air funnel.

Webster City Fire Chief Chuck Stansfield clarified on Wednesday the circumstances under which the tornado warning sirens are activated here.

“I just wanted to send out a note on our sirens,” he said in an email. “Sometimes people hear them better than others. It is due to the wind, or rain. Also, we try to test them on Saturdays at noon.

“We will set them off if the following happens:

— Tornado warning specifically in Webster City;

— Confirmed funnel cloud observed in Webster City;

— 70 mph wind or greater.

“Otherwise we do not set (them) off. We want the community to know that if they are going off, they need to seek shelter.”

It was about 3:15 p.m. Wednesday when the sirens sounded.

Stansfield added: “We have nine sirens in town, strategically placed, for maximum coverage.

“One misconception is that if you are inside a structure, they should be loud enough to be heard. In reality, they are meant to be heard outdoors to warn people to get inside and take shelter.

“The WCFD will never use the sirens as an all clear after the first time. If the siren is going off more than once during severe weather, that means take shelter.

“With the exception of testing, we make sure there is a real threat if they are set off.”