Thunderstorm Wind in Polk County, Nebraska

Wind gusts were estimated to be near 60 MPH, accompanied by quarter size hail.

Right in the middle of a line of thunderstorms along Highway 81 from Columbus to Hebron, heavy rain, hail and strong winds impacted the Shelby area shortly after 3:00 AM. A combination quarter to golf ball size hail and wind gusts near 60 mph were reported by the local NWS Cooperative Observer and local law enforcement. The thunderstorm quickly moved east into Butler county.

This was a case which occurs fairly often in late summer in which a 'not-so-obvious' shortwave, this time in southern South Dakota, triggers overnight thunderstorms. As the wave moved east, a low-level jet pushed moisture up the Highway 81 corridor while the weak upper winds became more favorably diluent in the area. Surface features were somewhat weak, but the night was unseasonably warm and 70 degree dewpoints had settled into eastern Nebraska. The brief intensification of the thunderstorm may have been aided by an outflow boundary pushing south across Highway 30 and into Polk county and into the back side of the thunderstorm line.