EF1 tornado in Polk County, Iowa

The tornado developed near the northwest I-35/80 urban loop and proceeded southeast through Urbandale, Windsor Heights, and into Des Moines, crossing I-235. Extensive tree damage occurred along the path along with damage to homes and power lines.

Convection from a passing upper level trough and associated MCS in the morning brought an initial round of non-severe storms mainly in Minnesota into the far reaches of northern Iowa. However, severe weather potential increased by the afternoon as the aforementioned trough and surface boundary made its way into Iowa. Conditions ahead of the boundary included 40-50 knot values of 0-6 km bulk shear, along with 3000-4000J/kg of instability, 25-30 knots of 0-3 km bulk shear and DCAPE values around 1000-1500 J/kg. As a result, a line of showers and storms developed in the afternoon and passed over central Iowa into the evening, with a handful of hail reports in central Iowa generally from penny-size to 2 inches, while the greater majority of reports involved severe wind gusts of 55-70+ mph and associated damage. Tornadic activity within the line of storms did occur, with a tornado developing in the Des Moines Metro area, causing primarily significant tree damage, as well as some structural and power-pole damage in the area as well. Heavy rain given plenty of warm and moist air over the area also resulted in isolated flash flooding, specifically over Black Hawk county.