Thunderstorm Wind in Hyde County, South Dakota

A large thunderstorm complex developed in south central South Dakota in the early morning hours of June 29th and tracked northeast across the state, finally exiting into southeast North Dakota and western Minnesota during the mid morning hours. Extreme winds were observed with this system. Two separate weather sensors recorded extraordinary peak wind gusts of 131 mph: the South Dakota State University mesonet station located at the Highmore Municipal Airport and a personal weather station three miles east-southeast of Holabird. These winds knocked down trees and damaged structures across portions of central and northeast South Dakota. Ground zero was the town of Highmore (population of roughly 650 residents) in Hyde county where up to 80 to 90 percent of residences and commercial buildings experiences some form of wind damage, with a number of vehicles and farm implements also being tipped and tossed. Residents at Highmore Health, the towns nursing home had to be evacuated due to damage to the facility. There was no loss of human life and injuries reported were due to post-storm cleanup operations. 3 horses died due to these high winds. Cost of debris cleanup in Hyde county alone topped out at 1.4 million dollars.

Electrical infrastructure was severely disrupted, causing $2.4 million in utility distribution damage across Hyde and Hand counties. Power was knocked out to 1,072 residents in Hyde County (94% of the county). Power generation was heavily impacted; at least 20 wind turbines were damaged or destroyed at the Triple H and North Bend wind farms, with replacement costs estimated at $50 million.

Day County suffered extensive damage, particularly around Andover, where straight-line wind speeds reached 100 mph. Extensive tree stands were leveled, grain bins dented, and buildings damaged at the Andover Threshing Grounds. Day County power damage reached $18,000, leaving 487 residents without electricity. A brief EFU tornado was confirmed near Andover.

Even as the storm system departed, wrap around high winds caused additional tree damage in areas that had just missed out on thunderstorm wind damage, with several trees and limbs down in parts of Aberdeen, and a peak wind gust measured on a personal weather station of 88 mph in the town of Westport (Brown county).

Governor Rhoden requested a Presidential Disaster Declaration to assist with damage cleanup and repairs for Hyde, Hand, Hughes, Buffalo and Stanley counties including Lower Brule and Crow Creek reservations.