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A false tornado warning was issued Tuesday. How do meteorologists decide when to issue warnings?

After receiving a report of a tornado on the ground from a member of the public northwest of Freeman, the National Weather Service in Sioux Falls issued a tornado warning. Now, they say no tornado likely produced.

261731+0428storm_sirenweb.jpg
Pictured here is one of the nine tornado sirens located throughout Mitchell.
Mitchell Republic file photo

FREEMAN, S.D. — The National Weather Service in Sioux Falls had issued a report of a confirmed tornado northwest of Freeman during Tuesday’s storm system, but meteorologists and county officials are now saying no tornado actually touched down.

As part of a widespread storm system that produced heavy rains, high winds and large hail across north-central Nebraska, eastern South Dakota, southern Minnesota and northern Iowa, the National Weather Service issued a tornado warning Tuesday that stretched from south of Clayton to west of Parker after receiving a report of an observed tornado northwest of Freeman.

However, on Wednesday, the National Weather Service said no tornado report would be written up after officials with the Hutchinson County Emergency Management said there wasn’t much evidence to confirm a tornado occurred.

“I drove that whole area yesterday and didn’t see any signs of touchdown,” said Barron Nankivel, emergency manager of Hutchinson County. “There’s not really any significant damage. There’s some siding and stuff that had damage, but nothing significant.”

Described as nature’s most violent storm, the National Weather Service defines a tornado as a violently rotating column of air touching the ground, usually attached to the base of a thunderstorm. Because Nankivel, whose job responsibilities include surveying severe storms, was not able to confirm a touchdown, a tornado cannot be confirmed.

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So, why did the National Weather Service issue a tornado warning when no tornado occurred?

According to Peter Rogers, a warning coordination meteorologist at the National Weather Service’s Sioux Falls field office, tornado warnings can be issued when a tornado is reported or when advanced radar systems detect it.

“With radar, we’re able to see the direction in which the wind is moving along the radar beam itself. What we’re really looking for is areas of wind that’s moving toward the radar nearby to areas where the wind is moving away from another radar so you can visualize rotations,” Rogers said. “However, the farther away [a storm] is from radar, the higher in the atmosphere you’re observing.”

Rogers said rotation readings on Tuesday, which were approximately 50 miles from the National Weather Service’s radar next to the airport in Sioux Falls, were estimated to be recorded approximately 4,500 feet in the air. That’s why they rely on reports from the general public, as well as trained spotters, such as law enforcement.

Tornado eight miles east of Alpena, S.D. (Submitted by Jessi Bucholz)
A tornado touches down in a field eight miles east of Alpena in this 2017 photo submitted by a reader.
Submitted by Jessi Bucholz

“When we’re issuing warnings, we’re taking reports from all different types of people. [On Tuesday,] a member of the public reported they had a touchdown near Clayton. That report came without a picture or a video,” Rogers said. “[On Wednesday,] we received another report from someone else in that same area that the initial report came from that sent us a picture showing the supercell in question.”

After comparing information from both reports from the public as well as Nankivel’s observations, Rogers said meteorologists determined there was most likely not a tornado.

“To the best of our understanding, what we think happened is that the downdraft portion of the storm was kicking up a bunch of dirt because of how dry it’s been. That dirt can sometimes curl or swirl to the surface and it could be viewed as a tornado,” Rogers said.

Receiving reports in real time, and with no real way to verify reports from untrained spotters, the National Weather Service decided to issue the warning as a precautionary measure.

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In discussion with emergency managers in Davison, Hutchinson and Douglas Counties, no major damage was reported as a result of Tuesday’s storm, though Nankivel reported hail that ranged in size from a ping pong ball to a baseball along the James River and near Clayton.

Officials in Douglas County said hail ranged in size from a quarter to a golf ball, though almost all of it stayed to the east of U.S. Highway 281.

Rogers said it’s very important for the public to be prepared for severe weather, especially tornadoes, no matter the time of year.

“Severe weather can come as early as March and continue into the early fall months,” Rogers said. “This past year was very unique in the sense that we had that tornado outbreak in Iowa.”

Storm system
A series of tornadoes struck the Midwest on Dec. 15, 2021, including 63 tornadoes in Iowa, setting a single-day record for the state.
Graphic courtesy of the National Weather Service

On Dec. 15, 2021, western and central Iowa was struck by 63 tornadoes, setting a single-day record for the state. One tornado, and EF-4 which struck near Winterset, Iowa, killed six in the wake of its nearly 70-mile path of destruction.

“That was very rare,” Rogers said. “For as long as our office has been in operation, we’ve never before issued a severe thunderstorm warning, let alone a tornado warning, in December.”

Tornadoes are most likely to strike South Dakota in June and July, Rogers said, cautioning that tornadoes can still strike anytime of the year.

Understanding how tornadoes form, what the National Weather Service’s warnings mean and being prepared are the best way to stay safe from tornadoes and other severe weather.

A South Dakota native, Hunter joined Forum Communications Company as a reporter for the Mitchell (S.D.) Republic in June 2021 and now works as a digital reporter for Forum News Service, focusing on regional news that impacts the Dakotas, Minnesota and Wisconsin.
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