roll cloud
© Angie Hutton
People near Memphis, Tennessee, thought they spotted a UFO a couple of weeks ago, but meteorologist have determined it to be a “roll cloud”.
Earlier this month, people near Memphis, Tennessee, spotted an odd formation in the sky after a storm.

It was an ominous, cylindrical mass that some likened to a UFO.

The mysterious sight prompted at least one person to snap photos, wondering what this UFO-like image might be.

Colby Hutton saw the mass in the sky over Adamsville, Tennessee, as he was driving over a bridge, his mom Angie Hutton told CBS News.

Angie shared her son's photo on Facebook, hoping someone could help them identify what it was. Local news station WMC-TV looked into the case.

It wasn't an unidentified flying object, and despite it's odd appearance, it has nothing to do with aliens at all.

It's a "roll cloud," the National Weather Service (NWS) explains. These rare cloud formations are "low, horizontal tube-shaped arcus cloud associated with a thunderstorm gust front," or sometimes, a cold front, NWS says.

Roll clouds are completely detached from the thunderstorm base or other cloud features.

Roll clouds usually appear to be "rolling" about a horizontal axis, but should not be confused with funnel clouds.

"These rare long clouds may form near advancing cold fronts.

In particular, a downdraft from an advancing storm front can cause moist warm air to rise, cool below its dew point, and so form a cloud," NASA explains.

Despite the dramatic formation's resemblance to a massive funnel laying on its side, NASA says roll clouds aren't thought to be able to morph into a tornado.

These clouds are so rare, you could go your whole life and never see one in person, CNET reports.