Is that a tornado? Wall, scud, shelf and other scary looking clouds


A well-formed wall cloud and tornado near College Park, Maryland, September 24, 2001. The tornado remained on the ground for 17.5 miles as it moved north-northeast through College Park, Beltsville and Laurel, Maryland. Source: Washington Weather

At the same time, a number of images were passed around as tornadoes that were clearly not tornadoes. In that light, we thought it would be good to examine a few of the most common scary looking clouds that sometimes are mistakenly called tornadoes.

Funnel vs. tornado


Photo of a funnel cloud, via NOAA Central Library.

To start, there is a very specific definition of a tornado.

The circulation must reach the ground. If not, and it’s rotating, it’s likely either a funnel cloud or a wall cloud (see below). Simply, a funnel cloud is a tornado that does not reach the ground. Often, you’ll see funnel clouds make it about halfway from the base to the ground, though it can extend much further or much less.

Sometimes it’s not always apparent if the circulation — if there is one — is reaching the ground as trees (see here) can block the view, or a condensation funnel may not be apparent even if there is noted circulation at the surface.

Example: A likely funnel cloud in Brambleton, Va from June 1. It’s not possible to tell if this touched the ground. The National Weather Service has not reported a tornado in this area.

Wall cloud


A wall cloud is seen on a storm that eventually produced tornadoes in Kansas on May 25, 2012. Photo by CWG photographer Ian Livingston.

Example of likely wall cloud with possible funnel forming from June 1 outbreak in Takoma, Washington, D.C.

Tail cloud


A wall cloud with tail cloud extending from it. NOAA Photo Library, NOAA Central Library; NSSL.

This video from June 1 in Greenbelt reported as a funnel or tornado closely matches what a tail cloud and wall cloud look like together.

Beaver tail


Photo of a beaver tail (top line) and tail cloud (lower) on a supercell thunderstorm by Chris Escandor, via NWS Rapid City, South Dakota.

Shelf clouds / roll clouds


A shelf cloud disonnected from the main cloud base (roll cloud) passes through Minnesota. Photo by Jon Zenzel, via NASA’s Earth Science Division.

Scud clouds


A scud cloud over southwestern Virginia. Photo by Ross Spoon, via Kevin Myatt’s Weather Journal.

Many of the photos circulated during the June 1 event were likely scud clouds. Example from Elkridge, Maryland.

Rain or hail shafts


A thin ropelike rainshaft is seen on a supercell in Kansas that eventually produced tornadoes on May 25, 2012. Photo by CWG photographer Ian Livingston. Note: This rain shaft was seemingly initially reported as a tornado on this storm and helped guide ground reports on the first tornado warning for it.

Related

Frightening Cloud Appears at H.S. Graduation

See more examples of non tornado illusions

Scary looking cloud club

Ian Livingston is a forecaster/photographer and information lead for the Capital Weather Gang. By day, Ian is a defense and national security researcher at a D.C. think tank.
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