Magnificent Meso

This rotating mesocyclone, laced with lightning, is seen in the north sky from this position along County Road D15 about a mile and a half west of Knoke, Iowa around 9:45 PM, Saturday, April 9, 2011. County Road N33 leads off toward the horizon at left center. At the base of the meso is a wall cloud lowering. The red lights in the background belong to a wind farm. It was difficult shooting this exposure of 9 seconds at f/8 and an ISO of 250, due to sustained RFD (rear flank downdraft) winds of 40-50 mph. The meso was part of a severe weather event in western Iowa on this evening that produced many tornadoes (we witnessed about ten) and vivid lightning. We ended our day of chasing about 15 minutes after this picture was taken.