Thunderstorm Wind in Polk County, Iowa

A nearly stationary front extended east to west across Iowa during the afternoon of the 22nd. The airmass was primed with dew point temperatures in the mid 70s south of the front and precipitable water values around 2 inches. Thunderstorms erupted during the early evening hours over Nebraska and advanced east into Iowa along the front. The storms were generally speaking now severe. Gusty winds and heavy rain was produced by most of them. Just as the storms approached central Iowa, a bow echo beta element formed in Dallas County. The bow echo tracked east into Polk County. Heavy wind damage occurred in eastern Dallas and Polk Counties. Winds gusted as high as 80 MPH as the storm roared through Des Moines. At one point, near 50,000 customers were without electricity in the metro Des Moines area. By the evening of the 23rd, power was restored to all but 13,000 to 15,000 customers. Some of the harder hit areas were without power for 2 to 3 days. Damage to trees and power lines was extensive. There were several reports of semi-tractortrailer trucks being blown over by the high winds and structural damage occurred to a few homes. Just before the storm moved into the metro Des Moines area, a very distinct funnel cloud was visible. The funnel cloud persisted for about 15 minutes, but did not come closer than about 40% of the way to the ground. The Des Moines public schools were closed for the day in what was the first time in the history of the city that schools were closed due to severe thunderstorm damage. The severe weather ended about as quickly as it began. After passing through Des Moines, the bow echo lost its character. In addition to the severe weather, flash flooding was a problem. The storms produced very heavy rainfall of in some cases nearly 2 inches in 20 minutes. Highways were under water in Dallas and Audubon Counties. Evacuations were considered for the town of Brayton in Audubon County, and Highway 144 was impassible in Perry.