Thunderstorm Wind in Mahaska County, Iowa

Medium sized tree split with lots of other trees damaged. Time estimated from radar.

Severe storms developed across northern Iowa on the nose of a strong LLJ into central Iowa during the very early morning hours of June 20th. While an isolated cell developed in southern Iowa initially, a larger complex of storms developed along the Iowa-Minnesota border around midnight and storms surged south along the instability and DCAPE gradient through the early morning hours. While a few storms resulted in hail reports, the overwhelming report type was for strong winds, often resulting in damage to trees and power lines. Storms also produced heavy rain with areas of three to five inches reported by late morning.