Once in a great while, I stumble upon extreme weather video unlike anything I’ve ever seen. Today’s example? A large, violent debris flash flood that gutted a creek basin in southern Utah Thursday afternoon (south of Bryce Canyon National Park, about eight miles north of Lake Powell).

How does a debris flood occur? Torrential rain falls along a dry basin. As the water flows downstream, it collects tree limbs, bushes, rocks and other debris along the way. The mass of debris causes the rush of water to slow, and the end product resembles a tsunami of sludge.

David Rankin, a self-described “flood chaser” (“As far as I know, I pioneered it [flood chasing],” he said) and photographer/narrator of the video above, said these debris floods are common in southern Utah.

“This happens every year around here,” Rankin said.

In Thursday’s flood, the debris flow was so strong it was “moving car-sized boulders” according to the National Weather Service.

“As far as the debris load, this was one of the most intense ones I’ve ever seen,” Rankin said.

Rankin captured the video six hours after three inches of rain fell to the north. He positioned himself 40-50 miles downstream to witness the debris flow first-hand.

As the video would suggest, the floods are potentially very dangerous.

“People die from these all the time,” Rankin said.