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This loop is the same as in the previous slide, except that 15-min CG lightning data are added.

The same office is asked to describe the loop, keeping in mind the radar failure at 19:00 UTC. From 17:32 to 19:02 UTC, lightning data show the formation of the squall line from more isolated cells, the development of a trailing stratiform region and formation of two notches on the backside of the squall line. From 19:02 to 21:32 UTC, lightning data show the bowing of the line over southeastern Iowa, the expanding area of stratiform precipitation and the development of new storms along the western side of the system.

The class is informed that most counties in southeastern Iowa experienced severe wind damage. A wind gust of 126 MPH was reported in Washington county.