There can be confusion about the types of clouds you're seeing. It might be a tornado, but it could be something similar. I talked about the similar but different types of clouds with Tawana Andrew.
Bill Burton: It's time for us to take a look at the Science Behind the Forecast with WAVE 3 meteorologist Tawana Andrew. Good morning, Tawana.
Tawana Andrew: Good morning. Today's topic is super important when reporting any severe weather that tends to happen in our area.
BB: And we've had more than enough severe weather throughout the area, including that tornado that touched down in Parkland about a month ago. So tell us about some of these clouds that people can confuse with tornadoes. Un-confuse us, educate us a bit, please.
TA: Funnel clouds and tornadoes, those phrases are usually used interchangeably, but there are some fundamental differences. So you have funnel clouds that are rotating columns of air, much like a tornado, but the key thing is that they do not reach the ground. With a pretty robust thunderstorm, they can quickly and easily form funnel clouds. You have the wind changing in speed, way and or direction as you climb through the atmosphere. That's called wind shear. And the wind shear increases the instability within a storm, leading to rotation. Now what happens as you have that rotation going on within a storm, the rotating wind actually pulls in the cloud rain droplets and that is what makes the rotation more visible. So when that rotation actually touches the ground or, in some cases, water, it will become a tornado or waterspout. Otherwise, it's just a funnel cloud. Another cloud formation that sometimes is confused for a funnel cloud is what we call a beaver tail.
BB: A beaver tail?
TA: A beaver tail! And it it looks like what it sounds like. So you have a thunderstorm pod, a cumulonimbus cloud pulling in air and as that air is pulled in, it's cooled as it's rising through the updraft. And the cloud basically appears flat and broad like a beaver's tail. Now, you'll notice if you're looking at it for a while — which I know some of y'all like to sit on your porches and watch the storms roll by — the size and the shape of that cloud will change as the inflow of the thunderstorm changes or strengthens or weakens. So you'll see it becoming a little bit more flat and wide or a little bit more thin. So that is not a tornado, it's just a beaver tail, which is a cool inflow that happens with a thunderstorm sometimes. The one that we get pictures of the most in severe weather scenarios are what are called scud clouds.
BB: Scud clouds, like the missile.
TA: Basically, yes. And there are small clouds that drift below a larger cloud. That can be caused by a couple of things. That can be caused by humid air rising and evaporating before it reaches the main cloud base as that humid air mixes in with the dry air, or the part that I think is really cool, they can be formed as raindrops actually break apart. And these fragments can actually accumulate below the cloud. Because the humidity is so high, they just kind of hovers and creates its own cloud beneath the main base of the cloud. And it's important to note that scud clouds do not produce severe weather, and they do not rotate. So an easy way to tell a scud cloud apart from a funnel cloud or tornado is that scud clouds are pretty jagged in appearance, and funnel clouds are smooth and if you look for a while, you'll notice that rotation and if you see it touching the ground, report it and get to a safe place.
