Long-lived supercell produces an EF4 tornado that tracks across northeast South Dakota, just missing the town of Bowdle, May 22, 2010. Early formation of the wedge is happening west of Bowdle now. Storm chaser Tim Samaras can be seen in the white truck after having deployed a probe on the road back there. Rapid and violent wedge formation is underway on the right/north side of the road in the image. Contrast was very poor at this angle but rotation was violent all around the tornado.