Scary-looking cloud isn't a tornado but a benign 'scud vacuum'
It looked like a tornado, but one clue in this video told us it was a benign cloud known as a 'scud vacuum' instead.
Danielle Kinnamont filmed a white tornado-shaped cloud moving slowly through a field in Thurmont, Maryland, on May 5. During the video, her young daughter asks, "Is it maybe fog?"
Essentially, you're right, kid.
In rare thunderstorm events during high humidity, often in the Eastern U.S., a tube of white condensation can form, giving form to the updrafts and downdrafts in a thunderstorm. Storm chasers colloquially refer to these tubular clouds clouds as "scud vacuums." They can look like a tornado but are benign, slow-moving, vertical fog banks.
Another great example of a scud vacuum occurred in Kentucky in 2021.
A "scud vacuum" in July 10, 2021 in Burkesville, Kentucky, (Kelsie Murphy Cooksey)
What are scud clouds?
Despite the chaser terminology, these tubular clouds don't meet the strict definition of a scud cloud, which are more typically darker, wispy, faster moving and dangle down from to the cloud. When trees or buildings are in the way and you can't tell if the cloud is touching the ground, it can get even more confusing.
These scud clouds were photographed on May 30, 2012, near AccuWeather's building in State College, Pennsylvania.
Scud clouds in State College, Pennsylvania, on May 30, 2012. (AccuWeather/Jesse Ferrell)
Often called "scary-looking clouds," by meteorologists because viewers reported them as funnel clouds or tornados, scud clouds may move up into the storm, but they don't rotate rotating like a funnel cloud or tornado.
Therein lies the rotation
The key to determining if what you're seeing is just a "scary-looking cloud" or a tornado is the rotation. If you see upward movement, but no rapid, blender-like rotation, then it's probably just a scud cloud. If things are spinning, take cover because you might be witnessing a funnel cloud about to touch down as a tornado.
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