NWS: Alpena tornado rare EF4
The tornado that demolished an Alpena farmstead last week was an EF4, the National Weather Service announced Wednesday.
The frequency of an EF4 tornado occurring in South Dakota is rare, according to Todd Heitkamp, a warning coordinator meteorologist for the NWS.
"Across the entire country, it was one of five EF4 tornadoes last week," Heitkamp said.
The June 18 twister started southeast of Lane, in Jerauld County, causing minor damage to a farm east of Lane, said Todd Heitkamp, a warning coordinator meteorologist for the National Weather Service. He said the tornado traveled nearly 12 miles north, ending northwest of Alpena with wind speeds peaking at 170 mph and was a half-mile wide. It destroyed a farm southwest of Alpena, traveling nearly 12 miles on the ground for more than 40 minutes.
Social media showed dramatic photos of twisters near Woonsocket on June 18, but Heitkamp said there were no confirmed tornadoes in Woonsocket, and that the closest confirmed tornado to that area was the EF4, approximately 6 to 8 miles west of Woonsocket.
There were at least 10 confirmed tornadoes in Jerauld County on June 18, including the EF2 that ripped through Wessington Springs destroying homes and businesses, Heitkamp said.
"The conditions were just favorable for these long-lived types of tornadoes," Heitkamp said. "So it made the conditions very ripe for tornadoes of this strength and magnitude."
Heitkamp said that the twister's strength was increasing as it headed north toward Alpena and the family farm it destroyed just outside the town.
According to the NWS website, only one injury occurred during the tornado and no fatalities.
"To get into a weather event like we did without any significant injuries or deaths, I think we need to be thankful for that," Heitkamp said.