July 21 Generation Gap

While the atmosphere was generating this severe storm in Johnson County, Iowa on Friday, July 21, 2017, a large gap appeared between the wall cloud--located more to the east--and a shelf cloud--spread out to the west. Above is a panoramic view of the storm at 4:40 pm CDT, as seen from the Interstate 380 rest area just south of Cedar Rapids, Iowa and just north of the Swisher, Iowa exit. The gap exhibited a dynamic churning motion, sort of a battle between the rotating and the straight line areas of wind.

4:42 pm. A slightly closer panoramic view of the area, with the strong updraft area inside the gap more visually prominent.

4:43 pm. A vertical and closeup of the finely textured gap, with the wall cloud residing at lower left.

Also at 4:43 pm, with a wider field of view of the "battleground."

4:44 pm. Just below the gap area. Nikon D7200 DSLR video frame capture. With a ragged funnel and a lowering here, a tornado seemed imminent, but failed to happen. Tornado warnings were issued further south for the towns of Kalona and Hills in Johnson County less than ten minutes later.

Radar capture for 4:45 pm. My position at the I-380 rest area is indicated by the target icon, with the arrow pointing to the more intense area of the severe storm. The white circle indicates the approximate location of the gap.