HURON – Tornado sirens were activated early Tuesday evening when strong thunderstorms moved through Beadle County, but the damage appears to have been caused by high, straight-line winds.
National Weather Service meteorologist Phillip Schumacher in Sioux Falls said most of the reports they received from the Huron area came between 6:15 p.m. and 6:30 p.m.
“You had multiple storms moving across that area in that time period,” he said.
The series of storms moved from the southwest to the northeast, generally following the same path, he said. It’s why there was a period of very strong winds, a short, calm period and then a second blast of strong winds.
Wind gusts of 58 mph were recorded at the Huron Regional Airport.
Branches were twisted off trees in Huron, but the strong winds that hit the Cavour area damaged outbuildings, power lines and trees, Schumacher said.
Radar indicated that the strongest and potentially most damaging cells skirted along the eastern edge of Huron as they approached Cavour.
Schumacher said the storm weakened as it neared Highway 81, with winds clocked at 40 to 50 mph in the Salem and Madison areas, but then reloaded to reach 65 to 70 mph wind gusts near I-29 and then into northwest Iowa and southwest Minnesota.
He said one-inch hail was reported southwest of Sioux Falls.
The rain total at the Huron airport was 79/100ths.
Beadle County Emergency Management Director Zach Nelson said he and the local severe weather spotters deployed to southern Beadle County, along Highway 37 and to the west.
“Our position was bad from the start due to the storm motion, so I attempted to return to Huron and set up on the east side of the James River,” Nelson said.
“As I approached town, my radar on my phone was indicating an area of either high wind or rotation, just southeast of 21st Street, almost over the river,” he said.
Nelson said his regional coordinator had a report of an unconfirmed tornado just east of Huron, but it hasn’t been verified.
The area had what’s called a velocity couplet signature, the sign the National Weather Service looks for to indicate high wind/rotation, he said.
“I observed two couplets on or near the James River on 21st Street and the second between Huron and Cavour,” Nelson said.
He said he did not have eyes on any funnel cloud or tornado. “However, if the signature had strong winds with it, that may explain the various damage done to small items and trees in Cavour.”
Schumacher said the weather service did get some reports of tornado sitings, but they were brief. Most of the damage was caused by the strong wind gusts, he said.
There were radar-indicated warnings of tornadoes in Beadle County, he said. It’s the goal of the weather service to issue tornado warnings based on that before an actual tornado is observed because to wait until an actual tornado is observed there could be injuries or fatalities, he said.
Cooler, drier and calmer conditions will dominate the weather for the next day or so, although thunderstorms are again in the forecast Friday night into Saturday.