Aerial picture of crop damage
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Map of Dane County Tornado Location
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Interesting Crop Damage, Walworth County
Late Evening August 26, 2004

Brad Poltermann, flying an ultra-light type aircraft, came across this interesting crop damage pattern in Walworth County. This corn crop was damaged by high winds from strong thunderstorms during the late evening of August 26th into the early morning hours of the 27th, 2004.

Expand image A on the left by clicking on it. Note the way the corn is knocked over in an alternating row pattern, especially in the field to the right. The inset image is a closer view depicted by the dashed area. Also note the area highlighted and labeled "wind shadow".  The clusters of trees and buildings blocked the wind coming from the left, thereby leaving the crops more or less untouched by the strong winds.

Here is an explanation from Brad, the pilot of the ultra-light:

"In photo A...looking north...the crop planted is all corn. The field to the left of the road near the bottom is a test plot of corn and there were several different varieties of corn. The field on the right side of the road (and photo insert) are two varieties from two different manufacturers. In photo B, this is a field which has two different varieties of corn from the same manufacturer. I met with the seed company today and we walked the fields. What we found was the root system on the fallen variety was not as strong as the other. The root quality on both were good but the high winds were just enough to tip one and not the other."

Brad goes on to explain how the field in photo B was cultivated.

"The field B was a field that I planted. We use a 16 row planter and we sometimes put one variety in 8 boxes and another in the other 8 boxes and that is how we have the varieties split the way they are. As we turn around at the end of the field and go back along side the last pass we end up with 16 rows of each variety alternating through the field. Your assessment of the wind shadow is accurate and obvious. The difference in some of the places of the corn being down more in one place and not in others in the same rows can be explained by soil types. What we found while walking the fields was the better soils produced a taller crop with bigger and heavier ears of corn. This added more weight and created a sail effect on the stalk and caused it to fall more than the shorter corn with less weight high on the stalk."

We very much would like to thank Brad Poltermann for submitting these intriguing photos and information. This page will be parked on our documented storms/weather page for later retrieval. is the U.S. government's official web portal to all federal, state and local government web resources and services.