July 15th had the right stuff. Good moisture, instability and lift were available, however shear was a touch weak. Storms formed over the southern end of the Big Horn mountains in Wyoming and tracked east/southeast becoming severe. One particular cell near the Pumpkin Buttes area southwest of Gillette, quickly intensified and became a strong supercell thunderstorm. Strong low level shear along a boundary caused it to spin viciously. A couple of funnels formed, but we could never confirm anything on the ground. However by the appearance and the damage we saw afterwards, it would not be a surprise if there was a tornado. The storm was quite electrified and intense. As it moved off the buttes towards Wright, it steadily weakened and dissipated east of that area.