[1][3] In the early afternoon, a second area of thunderstorms formed west of Des Moines and merged with the original bow echo line which then accelerated east-southeast into Illinois by 4:00 p.m.

Some embedded supercells, showing smaller-scale vortices on radars, produced narrower corridors of more intense damage, with measured wind gusts up to at least 110 miles per hour (180 km/h).

[1][2] The derecho crossed central and southern Indiana during the early to mid evening while its highest wind gusts decreased somewhat compared with those observed earlier in the day.

The system became a roughly west–east arc and turned more southward as it moved into Kentucky by late evening, dissipating gradually[1] By the end of the morning, the thunderstorms produced hail up to the size of hen's eggs and locally damaging wind in Nebraska.

[1] On Doppler weather radar, a large fast-moving mesocyclone associated of the track of a supercell was nearly in contact with the ground as it moved from southwest Boone County east-southeast across the northern and eastern parts of the Des Moines metro area.

The lighter shade, beneath the orange arrow, represented Doppler-estimated mean wind speeds in excess of 64 knots (119 km/h) all along the gust front, and the yellow circle are mesocyclone detections.