Oblivious To The Buildup

Westbound traffic on Collins Road NE near the intersection of C Avenue in Cedar Rapids, Iowa seem unaware of the presence of the mushrooming cumulonimbus cloud behind them around 5:40 PM on Monday, July 7, 2008. The storm cell was very isolated and very concentrated. The intersection in this image is located near the Rockwell-Collins facilities complex, toward the left. I took this photo from my driver's side window.