(CNN) South Dakota doesn't get a lot of tornadoes, but a twister there last weekend was particularly rare -- because it was spinning clockwise.

The National Weather Service says the anticyclonic tornado only lasted for about 45 seconds on June 15. That was long enough for it to knock down seven trees at a farmstead outside of Estelline, which is about 80 miles north of Sioux Falls.

While tornadoes occur infrequently in South Dakota, the June 15th tornado near Estelline, SD was even more rare: it was an "anticyclonic" tornado. Check out our website for additional details: https://t.co/K7i2MqWq11 #SDwx pic.twitter.com/7pg8clCvGt — NWS Aberdeen (@NWSAberdeen) June 17, 2019

Only about 1% of tornadoes that hit the Northern Hemisphere rotate in a clockwise direction, the National Weather service says. The weather service used radar data and video to make its determination about the South Dakota storm.

Becky Bates spotted this rare anticyclonic tornado on Saturday.

Becky Bates shot one of those videos while chasing the storm with her family.

"It honestly didn't seem unusual to me," Bates told CNN. "This was my first catch. I just chase for fun. But it touched down a couple of times while we sat and watched."

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