Weather Whys: Scud clouds vs. tornadoes

Weather Whys

COLORADO SPRINGS, Colo. — Scud clouds are often confused for tornadoes and funnels, but they are very different. They are harmless clouds that can spark a lot of concern when they form if you don’t know how to tell the difference.

Scud clouds form in association with thunderstorms. All thunderstorms have a downdraft that expels air from the storm down to the ground. If there is enough moisture beneath the storm, these downdrafts can form a detached cloud beneath the storm that reaches toward the ground. This is called a scud cloud.

Because they form with thunderstorms and can have a similar shape to funnels, they are often confused for them.

There are a few key things to look for so you can tell what you are seeing.

  1. Does the cloud have smooth edges or wispy edges?
  2. Does it have an irregular form or is it shaped like a cone or snaking rope?
  3. Is there rotation present in the storm?

If the cloud has jagged/wispy edges it is probably a scud cloud. Tornadoes and funnels typically have smoother sides.

If it has an irregular form, that is another key sign that it is not a tornado.

The rotation is the final clue to let you know what you are seeing. Scud clouds CAN form when rotation is present, so this does not rule it out as a scud cloud even if the storm is rotating. Instead, look for the lack of rotation. If the storm has no rotation it is probably not a tornado. Tornadoes must have this to form.

If you’re not sure what you are looking at, take a picture and send it to FOX21 or to the National Weather Service. We can help you figure it out.

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