SIOUX FALLS, S.D. (KELO) — One sign of spring is severe weather becoming more common. Not only do we keep an eye on the threat for tornadoes, hail, and flooding, but also damaging winds.
On July 28, 2025, a low pressure moved into an unstable environment across KELOLAND and sparked thunderstorms. Those storms quickly became severe.
WATCH: KELOLAND Live Doppler Spring Special
Six tornadoes were produced from isolated storms before they merged into a line and evolved into a derecho by the evening. Many locations experienced damage as wind gusts from 50 to 99 mph were reported.
Winds this strong can come from what is called a gust front. This happens when a rain cooled downdraft inside a thunderstorm makes its way down to earth’s surface. As the air underneath the storm cools down, warm and moist air is then forced upwards…