6.17.01 Rapid City, SD

My target for today was Vivian, SD. SPC had a moderate risk in southeastern South Dakota and the ETA and RUC models were showing CAPE bullseyes in the Winner, SD area. Winds in Vivian were east at 10-15 mph and the temp/dewpoint was 80/64. Everything was in place except a good forcing mechanism. The vigorous short wave was still in western WY/MT. Elevated weak convection was taking place in western South Dakota, but nothing was getting organized. It was clear by 7 pm that nothing was going to happen before sunset. SPC had issued a tornado watch for eastern South Dakota a few hours earlier, and it had since been canceled. I believe that the CAP was just strong enough to keep things from firing. If the short wave was a few hours earlier, it may have been a different story.

I began driving back west to Rapid City. I planned on photographing vehicles on I-90 after dark from an overpass east of Rapid City. I arrived at the overpass a little after 9 pm. After 20 minutes, I began noticing some lightning to my northwest. It quickly began putting down some impressive bolts so I moved north about 1/2 mile. I photographed an impressive barrage of lightning for about 30 minutes before continuing west towards Rapid City.

After arriving home around 1030 pm, I checked radar and found that an impressive cell had developed just southeast of New Underwood, SD. I was hoping that the activity was not over for the evening as the shortwave was still coming in from the west.

Around midnight, I noticed a linear radar feature extending SW to NE just west of the Black Hills. Occasionally, I have seen weak returns ride over the Black Hills and develop quickly into thunderstorms. I went outside to watch. I started noticing some weak sheet lightning flashes in what appeared to be some elevated cumulus. I suspected that updrafts were in fact starting to develop. I have seen this behavior before, and it usually is a precursor to a barrage of staccato bolts. It was quite an eerie scene as it moved right towards Rapid City. I set up two cameras and tripods. I was concerned that bolts would start hammering down any second so I stayed inside the house an aimed the cameras east out of the doorway to our backyard deck.

The first "flang" (flash-bang: a lightning strike so close that the flash and bang occur almost simultaneously) hit on the southwest side of the house away from the view of the cameras. It didn't take long, though, before bolts started raining down all over Rapid City. I stood back from the doorway expecting our neighbor's house to get struck any second. The light show was the best I had ever seen. Zeus was truly having a tantrum. The development moved east of Rapid City in about 1/2 hour, but the lightning continued non-stop. I watched and photographed until 130 am.

	View from Exit 94 overpass looking west-northwest.
	View looking north from 1/2 mile north of Exit 94.
	View looking north from 1/2 mile north of Exit 94.
	View looking northeast from my backyard deck in west Rapid City.






	View looking southeast.