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Tornadoes are the ultimate catch for storm chasers — and they’re also part of our name!

This lesson will cover some of the basics of tornadoes — from formation to how they move and beyond.

Tornadoes remain one of the great mysteries in weather, with the exact mechanisms for how and why they form being complex puzzles to put together. Still, we do know some of the basics. Most tornadoes form from supercell thunderstorms. These storms contain mesocyclones, which contain the necessary spin to produce tornadoes. Tornadoes are storm-scale processes, which mean that even within similar environments on the same day, you may get vastly different results between storms.

Here’s a primer:

The EF Scale, Explained

Tornadoes are rated by the damage they cause using the Enhanced Fujita Scale (EF scale). Tornadoes can range from EF0 (‘weak’) to EF5 (‘violent’). These descriptors are often misnomers though, because all tornadoes are a violently rotating column of wind by definition — but some are certainly more violent than others. Check out how the scale works below:

How Do Tornadoes Move?

Tornadoes move with their parent storms. For instance, if a supercell is moving northeast then a tornado associated with that storm will also generally move to the northeast.

However, tornadoes can take somewhat deviant tracks compared to the parent supercell. Typically these deviations are smaller, with slight left or right turns along their path (the El Reno tornado in 2013 was a slightly more exaggerated, but not unheard of example of this).

Sometimes though, tornadoes can really break the rules. The Greensburg EF-5 ended with a hard left turn that ended in a loop around itself, which caught unwitting storm chasers by surprise. As always, it is best to give tornadoes some breathing room so the small shifts they oftentimes make in their paths don’t put you in a bad situation.

How Big Can Tornadoes Get?

Let’s answer the question: How big do tornadoes get?

Tornadoes can be both very big, and quite small. Their sizes can range from a few yards across to a couple of miles!

Thus, tornado size is certainly a variable topic.

Interestingly, size doesn’t matter in terms of tornado strength. Bigger tornadoes do have a bigger footprint of possible damage, but the bigger size doesn’t necessarily mean the tornado is stronger.

In fact, many violent tornadoes are not the gigantic “wedge shaped” tornadoes that span 1/2 mile across or more.

How Big Do Tornadoes Get? Size Doesn’t Matter.

In this video, we try to break down some of the myths of tornado size and give some examples of truly behemoth tornadoes as well as a couple of helpful pointers about how the funnel isn’t just what the tornado is.

Tornado size is actually more than just the visible funnel. That is an important item to consider when spotting or chasing in tornado alley. 

So how big do tornadoes get? The answer is: potentially as huge as almost 3 miles across but most usually less than 100 yards wide.

And, regardless of size, all tornadoes are dangerous.


Not all tornadoes originate from a mesocyclone or even a supercell.

One type of non-supercell tornado is a land spout. Landspout tornadoes occur as the parent storm cloud is in its growth stage with the spin originating in the boundary layer of the storm.

Funnel Clouds

Not all funnel clouds are tornadic but most funnel clouds should be watched very carefully for the potential of a tornado. Keep in mind that where the funnel originates is a good indicator on how serious the threat is. A funnel in a wall cloud on a supercell might mean a tornado is imminent, whereas a funnel in the mid layers of the storm tends to indicate a shear funnel with a negligible tornado risk.

Back to: The Basics of Storm Season

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