7.6.00 Reva, SD

I was not expecting to chase this day. The cap had strengthened over most of South Dakota and there were no major forcing mechanisms other than upslope flow. The amplifying ridge was forcing the better dynamics further north into North Dakota as well. I got back from some errands around 330 pm and checked the satellite, radar and SPC update. SPC had issued a tornado watch box that included SE MT, SW ND and extreme NW SD. Satellite showed cumulus developing in far eastern MT just west of Buffalo, SD. I had to go check it out.

I was out the door by 345 pm and watched a rather strong storm develop far to my north. I suspected it was near the North/South Dakota border north of Reva, SD. It seemed to weaken as it moved north rapidly. Now the only target in view was some multicellular activity that appeared to be just west of Buffalo, SD. I headed that way on highway 85. By 602 pm, I was under the updraft base just south of Buffalo. I drove east on highway 20 to stay ahead of the base. By 635, the storm had increased in intensity an was starting to get better organized. I passed through Reva, SD at 706 pm and this is when the storm started developing into a beautiful LP supercell. It was the most photogenic storm I have ever witnessed. I just drove east on highway 20 as necessary to stay ahead of it and photograph it. It tracked right down the highway as well. At 731 pm, I passed through Prairie City and this was the time it started developing a barbed shaped beaver tail. (more like a devil tail) By 752, it developed a moist forward flank downdraft and at 805 pm, I heard a very distinct hail roar coming downwind from the vault region. I will never forget that sound as it was the first time I have witnessed this elusive phenomenon.

The storm started weakening at this point and by sunset, it had nearly completely dissipated. I was now in Bison, SD. What a treat on a day that I did not even expect to chase.

	550 pm 10 miles south of Buffalo, SD looking north. The storm was multicellular at this point.
	647 pm 10 miles east of Buffalo, SD looking west. The storm began strengthening as indicated by a more organized updraft base.
	721 pm The storm was now near Reva, SD and developing LP characteristics.
	729 pm Now a beautiful LP supercell.
	733 pm It started to develop an interesting beaver tail.
	737 pm The vault region was beautifully lit by the sinking sun.
	752 pm Shortly after this image was taken, I heard an elusive hail roar. It was very distinct and coincident with the development of a moist forward flank downdraft. This seemed to mark the beginning of the end of this storm.
	824 pm The storm had dissipated significantly by this time.
	831 pm This is all that was left of the updraft region as the sun dropped below the horizon.
Animated GIF	Click the box to the left to see a 139 KB animated gif of the LP