Back-to-back powerful Pacific storm systems to impact the Pacific Northwest and northern California through the end of this week with heavy rain, flooding, strong winds, and higher elevation mountain snow. A strong, long-duration atmospheric river will accompany the Pacific storms, bringing excessive rainfall and flash flooding to southwest Oregon and northwest California through the week. Read More >
Overview
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On June 29, 2019 a surface boundary was located across south central South Dakota. Very strong instability along the boundary was realized when a thunderstorm exploded along it. The thunderstorm updraft stretched energy along the boundary into a very slow moving tornado near Allen, SD. The tornado was visible for many miles. It was unusual because it only moved within a two mile area, but lasted about 40 minutes. Fortunately, it spun over corn fields most of the time. It damaged a house, blew over a couple of grain bins, snapped power poles, and carried grain bags. The tornado was rated EF-1 by an NWS storm survey team. More information about the environment of the Allen tornado can be found here. |
 Courtesy Chris O. |
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| Courtesy Gail S. | Courtesy Josie D. | Courtesy Ang G. |
Tornado
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Tornado - Near Allen, SD
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The Enhanced Fujita (EF) Scale classifies tornadoes into the following categories:
| EF0 Weak 65-85 mph |
EF1 Moderate 86-110 mph |
EF2 Significant 111-135 mph |
EF3 Severe 136-165 mph |
EF4 Extreme 166-200 mph |
EF5 Catastrophic 200+ mph |
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Photos & Video
Video courtesy Steve Wilson and OST / Bennett County Emergency Management
Tornado Pictures Near Allen, SD
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| Courtesy Laura H. | Courtesy Laura B. | Courtesy Lonna L. | Courtesy Luke K. |
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| Courtesy Dan F. | Courtesy Chris O. | Courtesy Ang C. |
Tornado Damage Survey Pictures
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| Collapsed barn door NWS Storm Survey |
Barn roof damage NWS Storm Survey |
Broken house windows NWS Storm Survey |
Power pole snapped NWS Storm Survey |
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| Grain bin foundation NWS Storm Survey |
Corn stalks piled against a house NWS Storm Survey |
Tornado scoured corn fields NWS Storm Survey |
Tornado scoured corn fields NWS Storm Survey |
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Media use of NWS Web News Stories is encouraged! Please acknowledge the NWS as the source of any news information accessed from this site. |
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