The National Weather Service issued a Severe Thunderstorm Warning for southeastern Lyon, western O’Brien, northeastern Sioux, and southwestern Osceola counties at 3:15 AM, which was to be in effect until 3:45 AM. Their radar had observed a line of severe thunderstorms from Alvord to Rock Valley moving east at 40 miles per hour.
The warning warned of wind gusts up to 60 miles per hour. It said damage to roofs, siding and trees could be expected.
At 3:55 AM, the weather equipment at the Sheldon Regional Airport detected a peak wind gust out of the north at 55 miles per hour. Major damage was also reported to a grain leg and a grain bin near Sheldon in the 3:00 hour.
At 4:53 AM, the Sioux County Sheriff’s Office advised motorists that there were multiple trees down in Hull and some were blocking roadways. At 6:13 Thursday morning, they advised that city crews had removed the trees blocking the roadways in Hull.