Courtesy Josh Deere

The tornado that touched down on Colorado's Mount Evans last weekend is the second-highest ever recorded by the National Weather Service.

A twister that touched down in Colorado's high-country on Saturday is estimated to be the second-highest tornado ever recorded in the U.S. by the National Weather Service.

There were four different reported sightings of the high-altitude hit the northeast side of Mount Evans — a prominent mountain located about 60 miles west of Denver. The National Weather Service estimates the tornado's touched down at about  11,900 feet in elevation.

Bob Glancy, a National Weather Service meteorologist in Boulder, Colo., told NBC News that this tornado above the treeline is "not unheard of," but "just unusual." Most tornadoes in high terrain are weak, he said.

For the last two decades, Colorado has averaged 50 tornadoes a year. But Glancy said the "vast majority" occur on the plains east of Interstate 25.

Colorado Springs resident Josh Deere told The Denver Post he saw the funnel as he was driving with his family to the top of Mount Evans.

"As we drove past it, we were able to look back and had some spectacular views of it as it spun and then eventually broke up as it entered the mountain cove," Deere told the Post.

The highest recorded tornado occurred in 2004, according to Glancy, over Rockwell Pass in California's Sequoia National Park. That twister was estimated to be at 12,000 to 12,500 feet.

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