Weather 101: “Look! It’s a funnel cloud” or is it? Difference between funnel clouds and SCUD clouds

The Distinction Between A SCUD Cloud & Funnel Clouds.

Written by Mike Susko.

Published: April 19, 2021 / 09:50 PM Central Daylight Time.

Revised: Apr 19, 2021 / 09:50 PM CDT.

When severe storms move into our area, you may catch a cloud that appears to be lowering towards the ground and think that it might actually be a fast-moving SCUD cloud. Once you glance up at the sky, you might not think it’s a funnel cloud.

SCUD Clouds

During a thunderstorm, SCUD clouds develop when air ascends in regions of heightened moisture levels, despite their resemblance to funnel clouds, their creation process is actually quite distinct.

The term SCUD is actually an acronym that stands for “Scattered Cumulus Under Deck”.

Scud cloud near Greenland. Notice the cloud feature’s non-smooth appearance. Image: Kama Davis

Although they appear threatening, SCUD clouds are benign and do not generate extreme weather conditions.

The biggest differences between them are that they are often separated from the bottom of the thunderstorm, they do not rotate, and they are cloud funnels known as SCUD clouds.

Definition of a SCUD cloud. Image: American Meteorological Society Glossary of Meteorology

Funnel Cloud

Unlike SCUD clouds, funnel clouds form from a spinning updraft and are linked to the base (or underside) of the thunderstorm.

Funnel cloud north of Sallisaw, OK. Image: Logan Burress

Tornadoes are not exclusively funnel clouds, but a funnel cloud has the potential to become a tornado. Unless it makes contact with the Earth’s surface, a funnel cloud does not qualify as a tornado.

Definition of a funnel cloud. Image: American Meteorological Society Glossary of Meteorology

The clouds are not smooth while rotating, due to the smoothness of the clouds Funnel. If the features on the edges of the cloud are smoothed, one can tell if it is a cloud funnel from a cloud SCUD by using a trick.

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