A tropical tornado is a special kind of tornado that is formed mostly from wind shear and less through instability. Because of that, they tend to be weaker and shorter-lived than the tornadoes that form from supercell thunderstorms in the spring or lines of thunderstorms in the winter.
Tropical TORs
Since shear is the driving force behind tropical tornadoes, they often spin up very quickly and disappear just as fast. This is because the ability to produce a tornado is just as much aboiut moving air up-and-down as it is about spinning it in a circle.
So the shear that causes the spin in the atmosphere has to wait for juuuust the right amount of upward and downward motion in the atmosphere to pull out a tornado. And since that delicate balance is often short-lived, so are the tornadoes themselves.
And because they are short-lived and the upward-and-downward motion isn’t as strong as other atmospheric situations (like along a cold front or in a supercell thunderstorm) the tornadoes themselves aren’t as strong.
Supercell Thunderstorm & QLCS TORs
Tornadoes that form from supercell thunderstorms or QLCSs (quasi-linear convection systems) tap into the shear in the atmosphere but also rely on the amount of instability, too.
I would do an entire whole post about tornado formation in these situations, but the reason that these are much stronger and better organized than the tropical tornadoes is because these tornadoes have access to a much better “parameter space” than the tropical tornadoes.
That is to say, there is almost as much shear, with better instability, higher low-level helicity, a better balance between all three, and better forcing as well as a focal point for development.
Tropical tornadoes just sort of ‘happen’ while these types of tornadoes ‘develop’ in a spot.
Here is a video from my class at the University of Southern Mississippi talking about tornado formation.
