My last day out would be one of my favorite on this trip. A boundary was present from overnight convection across northern South Dakota into North Dakota. I decided to play where the winds were backed and the approaching short wave would intersect the boundary. By 2 PM a supercell rapidly developed along this boundary near Buffalo, South Dakota. This storm became a monster supercell and produced copious amounts of baseball sized hail and a small tornado just northwest of Reva, South Dakota. Then the first cell died as it crossed the boundary into North Dakota, and a second very nice HP supercell developed back over Buffalo.