A line of powerful thunderstorms — which the National Weather Service identified as a bow echo — roared across southeastern South Dakota early Wednesday, uprooting trees and causing power outages in numerous locations.
The storm also ruptured a gas line that briefly forced a partial evacuation in the Hutchinson County seat of Olivet.
The National Weather Service (NWS) reported damage to grain bins and trees in the Parkston area. The Argus Leader reported an outbuilding north of Armour and east of Corsica was completely destroyed. Also, some farm structures were destroyed at one Wakonda rural residence, according to the NWS website.
Brad Adams of the National Weather Service in Sioux Falls told the Press & Dakotan that the storm produced wind gusts of 80-90 miles per hour in a line ranging from the Parkston to Menno areas in Hutchinson County, and then down toward the Missouri River valley.
Olivet was in that line of fire and was smacked hard by the storm, which caused damage throughout town. Hutchinson County officials kept the courthouse closed until noon while residents cleared streets of branches and debris.
"At (5:50 a.m.), we just heard lightning and thunder and cracking and hail," said Jane Gramkow, a member of the Olivet town board. "It was more like a straight wind and lightning. We heard cracks; I suppose that was the trees coming down."
She said the storm lasted at least 20 minutes, "but then it stayed dark so long, you couldn’t go out and tell."
Gramkow noted that a gas leak was reported on Fourth St. after a falling tree took down a chimney which clipped a gas line when it collapsed. People along two streets were evacuated for a time while the situation was resolved.
Gramkow estimated that every street in Olivet sustained some damage.
"(It affected) pretty much all the houses, but luckily, there were no damages and no fatalities," she said. "Everybody was OK that I’m aware of so far."
When contacted Wednesday evening, Gramkow said power was restored to the town at about 3 p.m. and many of the fallen trees had been cleared away.
Overall, the cleanup went well. "It was everybody helping everybody; neighbors helping neighbors," she said.
Meanwhile, Menno, located five miles to the east, also saw widespread damage to trees, with cleanup efforts underway soon after sunup.
Delmont was also hard hit, with damaged buildings and destroyed trees from the pre-dawn storm. Power was out for most of the morning until returning at about 1 p.m., according to local reports.
Adams said Wednesday’s storms fit the pattern of a bow echo, which is a destructive line of storms marked by powerful winds.
"It did have that signature on radar," he said. "The storms can gust out when you have a storm setup like we did overnight. So it was very much a bow echo system."
He said the storm line intensified as it moved into conditions that were ripe for destructive development.
"(The storms moved) into a conducive area for intensification overnight, with plenty of abundant moisture and a strong southerly (wind) flow," he said. "So all the ingredients were there for these storms to continue into a long-duration event overnight and into (Wednesday) morning, which is what occurred."
The NWS issued a tornado warning early Wednesday that included the cities of Armour, Parkston, Tripp, Delmont, Alcester and Wakonda. Other areas were under severe thunderstorm warnings.
Flash flood warnings were issued for Lincoln and Minnehaha counties as the storm system made its way east.
Xcel Energy said a tree fell on a power line knocking out service to about 660 customers in Lennox. Power was restored several hours later.
According to the NWS website, area rainfall amounts included 4.65 inches southwest of Stickney, 3.70 southwest of Sioux Falls, 2.02 at Dimock, 2.00 at Parker, 1.97 at Parkston and 1.17 at Marion.
Yankton was hit by a thunderstorm shortly before 6 a.m. Wednesday. The storm left .80 of rain at the airport and came with strong winds. However, only minor tree damage was reported.