STORLA -- Though tornado sirens wailed west of Mitchell on Sunday evening, the National Weather Service says no tornado ever touched down.

In one of the stronger storm systems of the year, towns west of Mitchell saw strong winds, heavy rains and sizable hail.

Shortly before 7 p.m., the National Weather Service issued a tornado warning for northeastern Aurora County, southwestern Sanborn County and northern Davison County after identifying a radar-indicated tornado.

The storm system intensified, producing strong rotation in the clouds near Storla, and was heading in a southeasterly direction toward Mitchell. The total area under the tornado warning included almost 20,000 people.

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However, one meteorologist said that a rotating funnel cloud does not qualify as a tornado until someone witnesses it touch the ground.

“A radar indicated warning just means that we’re seeing enough rotation that it could produce a tornado,” said Andrew Karlin, a meteorologist at the National Weather Service in Sioux Falls. “There were several storm chasers on the storm, but we didn’t get a report of a touchdown.”

The National Weather Service can’t be everywhere at once — it relies on storm chasers and trained members of CoCoRaHS (a program for members of the public to report hyper local weather) to report local information back to their Sioux Falls station.

One storm spotter nine miles south of Wessington Springs reported 1.23 inches of rain, while another three miles southwest of Letcher reported one-inch hail. A third reporter located 10 miles north of Plankinton said the wind gusted up to 90 mph.

Davison County Emergency Management coordinator Jeff Bathke said that his office has fielded no reports of damage to public or private property. Skyler Kehn, Aurora County’s coordinator, said the same.

Bathke was flying through the storm as the storm system hit Sioux Falls. He said that the lightning lit up the heavy rain in the sky, offering a unique glimpse into the size of the storm.

Kehn was driving home from Wilmarth Lake when the heavy winds nearly pushed him off the road.

Both coordinators said their counties test their tornado sirens once a month, and that equipment failures are rare, but immediately fixed.

Kalin said that even though South Dakota isn’t inside the peak window for tornadoes, that doesn’t rule tornadoes out anytime there’s severe weather.

“Typically our tornado season in southeastern South Dakota is typically late-May to late-June, but that doesn’t mean that they can’t happen other times,” Kalin said. “Our broader severe weather season ranges from mid-April to mid-September.”

In fact, Kalin said areas that fall under NWS Sioux Falls’ coverage are at risk for more severe weather — including tornadoes — this week.

“Its going to be a relatively active week, in that we have a lot of small chances of thunderstorms,” Kalin said. “Overall, severe weather risk is on the lower end, but any storms that do develop would have the potential to be strong to severe.

Kalin said that tornadoes fall into the same area of small risk, but that he can’t rule them out this week.

Currently, the NWS forecasts a chance of thunderstorms in the Mitchell area on Tuesday afternoon and Wednesday night, followed by lighter — but more likely — showers for most of Friday.

Kalin said that people should always be prepared for tornadoes, having access to multiple reliable sources for weather watches and warnings, and should keep an emergency kit packed at all times.