Massive EF 4 wedge tornado near Bowdle, South Dakota: May 22, 2010 chase report




Chase images and log by William T. Hark, M.D. Copyright 2010. Video and pictures available for license


This was an amazing and unexpected chase day that I almost blew off. I started the day in North Platte, Nebraska. After checking data, the best area for tornadoes would be in South Dakota. There was a trough over the western states and decent 500mb southwesterly flow across the northern plains especially over South Dakota. The best (southeasterly) surface winds would be over South Dakota, and the 12Z NAM showed a CAPE bullseye of up to 4000 Jkg in central South Dakota. I also really liked the strong southeasterly 850mb winds forecast at 1PM for northern South Dakota. They would change to southerly by 7PM per the NAM. The best chaseable tornadoes often occur with south to south easterly winds at the 850 level. Cons included a very large cap that could suppress or eliminate storm formation in the target area. There was definitely bust potential. I headed north, stopping in Valentine to reassess whether to chase that day. I even heard that VORTEX 2 was not chasing that day. After checking data, I was more hopeful and continued northward to an initial target of the Pierre area. I decided to stay on the east side of the Cheyenne River Indian Reservation and Lake Oahe because of limited road network. I also talked with Tim Vasquez who liked the area around Seneca. By early afternoon, I was waiting for initiation at a crossroads south of Lebanon, South Dakota.

At approximately 4:05 PM CDT, I noticed some agitated cumulus to the west. These were slowly moving northward and dissipating. There were no other areas of cumulus in the vicinity. I was initially worried that I'd take off after one storm and miss out on a better storm to the south. Finally, one area developed into towers and became dominant by 4:42PM. This would become the famous Bowdle storm. I drove north on 47 to Hoven and then west on 20 to the north-south 83. Two adjacent storms exploded to the east. I first stopped on a hill just before 83, waited and watched as the storms matured. The mosquitoes were awful in that area and I shifted east by a mile to 83. There were only a few chasers around including Jeff Piotrowski and his wife. We chatted and watched the storm intensify. As the storms consolidated and shifted northeast, I didn't want to get cut off by the core. The storm was also showing significant rotation and was tornado-warned. I drove north on 83, then east on a gravel road that passed through the town of Lowry. There was an interesting lowering to northwest at 6:03 to 6:05 PM, and I was not sure if it was a tornado. Of more concern was visible rotation to the south. The gravel road briefly turned northward, then east. North of Swan Lake, I turned north on 315th Avenue. Instead of turning east again on 140th street as most chasers, I continued north and had planned to take another east option as shown on Delorme. It didn't exist. I had to drive farther north and closer to the core for the next east option. I reached my east option (State Road 12) at 6:13 PM, and I could see a tornado forming to the south by 6:14PM. I stopped briefly to film it at 6:16 PM and was hit with RFD. My Z1 fell over in the wind, breaking the tripod mount. I was pelted with rain and hail. I blasted east as the tornado rapidly approached from the south. It vanished at 6:18PM, then quickly reformed as a stove-pipe at 6:19 PM, and I again stopped briefly to film it. The tornado was to my southeast and moving northward. I almost didn't make it as the tornado expanded while shifting northward toward the road. The tornado lost its classic form and became an enlarging mass of swirling dust under a giant meso. The narrow tornado morphed into a massive wedge. I stopped and watched it pass to my west. The tornado was now north of the State Road 12 by 6:26PM. I think it was making a right turn as it was moving more easterly just north of the road. Filming was difficult due to wind and rain. The wedge and huge rapidly rotating meso was incredible. The storm structure was as wild as the tornado. I probably would have had better video if I was farther away. I drove east filming the wedge to the north and was able to get ahead of it. It was rather slow moving. I was worried about the town of Bowdle, but I noticed the path would take it just north of town. Here was an opportunity for great video while having an escape route. I turned north on 47, stopped and waited for the tornado to pass to my north. The winds were intense and I was still having difficulty filming due to the rain and fogging on my windshield. The tornado knocked down several long distance power transmission towers before it crossed the road. I was able to zoom in at 6:40 PM for a close view of a falling transmission tower. I turned south, then headed east on 12. The wedge became wrapped in rain and lifted at some point. I saw another tornado, a nice backlit elephant trunk to the north. It lasted for a couple of minutes. There may have been another brief tornado at 7:01 Pm that was difficult to see through rain curtains to the northwest. I drove east as the storm became a monster HP beast. As it was getting dark, I had no desire to see if there were more tornadoes by venturing north into the bear's cage. At Aberdeen, I turned south and ended the chase. There was a nice display of mammatus clouds as I drove south. I spent the night in Mitchell, South Dakota. The next day, I did some landscape photography and rested.

This was one of the best chases that I have ever had. I love seeing tornadoes but it is a very special occasion to watch the birth of a tornadic storm from an area of cumulus and follow the storm through the first part of its life cycle. This storm also had a nice combination of beautiful structure and tornado. Unfortunately, the main tornado did cause some damage and was later rated an EF4.

Aggitated Cu 4:23PM CDT (P)

A dominant tower 4:42PM

5:17PM developing storm (P)

6:03 PM view to NW from
near Lowry. ?tornado

Initial tornado 6:14PM
View to SE from 12

Initial stop to view tornado 6:16PM
view to SE from 12

Rapidly moving tornado 6:20PM
view to SE from 12

Tornado north of 12, east of Bowdle (P)

6:31 PM, tornado north of 12

6:32 PM view from 12 to NE


6:37 PM


6:40 PM, on 47 north
of Bowdle, tornado to NE

falling power pole 6:40 PM
north of Bowdle

east of Bowdle, 6:52 PM
view to west northwest (P)

tornado 6:53 PM east of Bowdle
view from 12 west northwest (P)



Nice contrast tornado 6:51 PM

Another possible tornado 7:01 PM
view from 12 to west northwest

Storm is now an HP beast 7:44PM (P)



Digital photos are labeled with (P). Other images are HD video captures.

Post Storm Data

Storm chase map NWS Prelim Damage Survey
NWS Prelim Tornado Reports
Hi-Res Radar loops and damage reports from Aberdeen
NWS, South Dakota.


Archived forecast model, surface and upper air data for May 22, 2010

12 Z Tornado Prob. Day 1 graph&Day 1text Surf. analysis 15Z 12Z 500mb
12Z 700mb 12Z 850mb 1343Z surf 1843Z surf
1345Z sat 1831Z sat 2045Z sat 1800Z SPC Meso TDew
2100Z SPC Meso TDew 1800Z SPC Meso 1kmEHI 2100Z SPC Meso 1kmEHI 1800Z SPC Meso SBCAPE
2100Z SPC Meso SBCAPE 1800Z SPC Meso SigTor 2100Z SPC Meso SigTor 12Z NAM 18Z 850mb
12Z NAM 00Z 850mb 12Z NAM 00Z 700mb 12Z NAM 18Z Sfc 12Z NAM 00Z Sfc
12Z NAM 18Z CAPE 12Z NAM 00Z CAPE 12Z NAM 18Z Pcp 12Z NAM 00Z Pcp
12Z NAM 00Z SRH 15Z RUC 00Z 700mb 15Z RUC 0300Z 700mb 18Z RUC 00Z Sfc
17Z RUC 0200Z Sfc 18Z RUC 00Z CAPE 18Z RUC 00Z Pcp 17Z RUC 0200Z Pcp
4KM WRF ref 2300v023 4Km WRF ref 0000v024 ABR 12Z Sounding obs ABR 00Z Sounding obs


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