A line of severe thunderstorms is expected to move across eastern South Dakota in the late afternoon July 28, potentially bringing heavy rain and hurricane-force winds to the region.
Severe weather is expected to occur between 4 and 7 p.m. in central South Dakota, between 7 and 10 p.m. along Interstate 29, and between 9 p.m. and midnight in southwest Minnesota, according to the National Weather Service.
The main concern will be wind gusts of 70 mph or more, though large hail and a few tornadoes are also possible, the weather service said.
Thunderstorms could combine to become a derecho as they drift over eastern South Dakota, according to the National Weather Service’s Weather Prediction Center. Heavy rainfall over saturated ground could also lead to scattered instances of flash flooding in the region.
The area most at risk for high winds was north of Interstate 90, including Aberdeen, Brookings, Huron and Watertown. The weather service said it “highly advised” securing any items that might easily blow away before the storms arrive.
A portion of southeast South Dakota was already under an extreme heat warning, with the heat index expected to reach 107 degrees by Monday afternoon in Sioux Falls.
Severe thunderstorms are expected to hit eastern South Dakota in the late afternoon July 28, potentially bringing hurricane-force winds to the region.
What is a derecho?
A derecho is a widespread, long-lived wind storm associated with a band of rapidly moving showers or thunderstorms, according to the National Weather Service. A derecho can produce destruction similar to tornadoes, and the term “straight-line wind damage” is sometimes used to describe derecho damage.
“By definition, if the wind damage swath extends more than 240 miles and includes wind gusts of at least 58 mph or greater along most of its length, then the event may be classified as a derecho,” the weather service says.
USA TODAY reporter John Bacon contributed to this report.
This article originally appeared on Sioux Falls Argus Leader: What to know about July 28 severe weather in eastern South Dakota