Tornado in O'brien County, Iowa

An eyewitness observed a tornado develop 2 miles northeast of Archer south of 350th Street in an open field. The tornado tracked northwest slowly over the next five minutes through open fields. After crossing Pierce Avenue, the tornado dissipated. There was no known damage, resulting in an EFU rating. The location, track, and a maximum path width of 25 yards was estimated from video.

At late afternoon, considerable moisture focused near a strong warm front from low pressure across northeastern Nebraska through northwest Iowa. Climatologically significant mid-level lapse rates produced a strong capping inversion which gradually weakened north of the warm front. Storms initiated with effective deep-layer shear from 40 to 50 knots and quickly became severe hail producers north of the warm front across southeast South Dakota into southwest Minnesota during the late afternoon, with additional storms developing in proximity to the surface wave across northwest Iowa. One of these latter storms produced two weak tornadoes across northwest Iowa.