"Iowa Bow Echo"
29 June 1998

On 29 June 1998, a bow echo and its associated derecho evolved from a supercell thunderstorm that had formed near the Nebraska and South Dakota border. The supercell entered Iowa and a strong rear inflow jet formed, causing the storm to take on the bow shape. As common with the bow echo, a derecho was present, a feature that can and did produce very strong straight-line winds. Many reports of winds greater than 60 knots were noted, as well as were several tornadoes, hail, heavy rain and small stream flooding in association with the bow echo.

As the storm entered Illinois, it continued to produce severe weather. Reports of strong straight-line winds, microbursts along the front edge of the bow echo, tornadoes, flash flooding and hail were noted. Most of the damage was produced by the straight-line winds in both states. Winds were measured at 60-80 knots sustained, with gusts reported to over 100 knots. In Washington, Iowa a gust was measured by a school net station of 123 knots.

Damages of over $150 million were estimated in Iowa, and Illinois reported damages of just over $15 million. There were 171 reported injuries in association with this storm, and 1 fatality.

Case Study 39