Is that a tornado? The scoop on SLC’s (scary-looking clouds)

Sirens in Callaway County on Monday night alarmed many residents into thinking there was a tornado. Following the activation of outdoor sirens in the county, the National Weather Service out of St. Louis said the low light conditions and and rapidly moving clouds made the clouds look ominous.

Those clouds, which are responsible for numerous false tornado reports nationwide are a member of a unique phonemena collectively known as scary-looking clouds (SLCs). Seeing them causes many observers to think the worst. There are a variety of SCLs, but the one that tracked through Callaway County, was known as a scud cloud.

A scud cloud is nothing more than a detached cloud found at the base of a cumulonimbus cloud. It is not rotating and is therefore harmless. They are more often described as looking like torn out pieces of cotton balls. Scud clouds form because of rain-cooled air. It occurs as result when water vapor condenses at the base of a cloud. Due to wind shear in the environment, the clouds can move up and down tricking the eye into thinking they are rotating, but they aren’t. It’s for this reason that numerous false tornado reports are reported to the National Weather Service.

Scud clouds aren’t the only scary-looking clouds. There are a variety of other clouds quite common clouds that invoke fear into many; those include shelf clouds, roll clouds, tail clouds, beaver tail clouds and rain/hail shaft clouds.

SHELF/ROLL CLOUDS:

These are usually the easiest SLC clouds to identify and are responsible for many false tornado reports as well. These clouds usually resemble waves in the atmosphere and are formed by cooler air rushing out ahead of a storm. The biggest difference between roll clouds and shelf clouds is their placement. Shelf clouds are attached to parent storms;roll clouds are detached from many clouds and look like they are rolling through the sky.

TAIL CLOUDS:

Tail clouds, while harmless, do indicate that severe weather is likely. Tail clouds are usually seen attached to the wall cloud of a severe thunderstorm. The tail forms in the downdraft of the storm, which is an area of high moisture. These clouds are very common during severe weather season and usually appear like shredded clouds coming off of the storm, in the direction that the outflow is heading.

BEAVER TAIL CLOUDS:

Beaver tail clouds have a similar appearance as a tail cloud, although they are much longer and shaped like a beaver’s tail. It’s also attached to the main base of a storm. The clouds form in an area where the updraft and downdraft meet, which creates the cloud. The clashing of the two winds create the squashed appearance like a beaver’s tail.

RAIN/HAIL SHAFT CLOUDS:

This one isn’t a cloud, but it warrants attention as it confuses many who see it. Some storms have a small and dense rain shaft, which can look like a tornado. While it isn’t even a cloud, it looks like one because of the rain being darker than the surrounding air. It gives the shaft the appearance of being a tornado, when it fact it’s just associated with a supercell.

While on the topic of scary-looking clouds, it’s important to go ahead and give you the difference between a funnel cloud and a tornado. Many confuse the two, but a funnel cloud is never a tornado unless it comes in contact with the ground. A funnel cloud is a vilolently rotating column of air that has yet to reach the ground. Once the funnel reaches the ground it then becomes very dangerous and become a tornado.

Each and every cloud is unique and for many they look scary enough to resemble a tornado, though that’s rarely the case. It’s important to remember to not let fear play a role in identifying clouds, but you should still use caution.

In the end, if you can’t determine whether you’re observing an actual threat or just a scary-looking cloud, it’s always important to remember to take cover, because some storms on microscale levels can drop a tornado without being warning.