Storm clouds(Erik Gazi / Unsplash)Bill Burton: It's time for us to take a look at the Science Behind the Forecast as I am joined by WAVE 3 meteorologist Tawana Andrew. Good morning, Tawana.Tawana Andrew: Good morning. We are continuing our series on cyclones today. BB: Yes, last week, we covered the basic cyclone, if you will, as well as some of its cousins, if you will. But today we're talking about mesocyclones. What exactly is a mesocyclone? TA: A mesocyclone is not a traditional cyclone. So the traditional cyclone is a large scale circulation of winds around a central low pressure system. What we typically see with cold fronts and warm fronts moving across the country, that's a normal cyclone. That's a mid-latitude cyclone. However, a mesocyclone is actually part of a supercell, and it's around two to six miles in diameter, which is a huge difference from the 900 to 3000 miles in diameter that you can have for a mid-latitude cyclone, right? Just a little bit of a difference in size there. The National Weather Service's definition of a mesocyclone is a rotation signature appearing on Doppler radar that meets specific criteria for magnitude, vertical depth and duration. So in English, what this means is that on a radar, meteorologists will look for rotation happening in the atmosphere, and this persistent, rotating updraft within a supercell is the mesocyclone. For a supercell to develop, you need a couple of things. You need buoyancy, which basically means you have that warm, rising air going on in the atmosphere. You also need strong speed and directional wind shear of at least 46 miles per hour, and that has to be between the ground and up to about 20,000 feet. So that qualifies the magnitude and the vertical depth that they were talking about. Now in terms of duration, these mesocyclones can last for hours on end. This is why you you'll see with strong super cells, they'll track across multiple states, lasting for a long time, and that is because they have a very good mesocyclone going on within that storm and within a supercell like this, you can end up with damaging winds, large hail and tornadoes. Once you start to hear meteorologists talking about mesocyclones, that's when you really need to have your ears perk up and start to pay attention a little bit more, because something severe could be happening down the line. Now switching gears a little bit. We're going to talk about subtropical cyclones. Last week, we talked about the tropical cyclones and the mid-latitude cyclones. So we're adding another one on top of that. We have subtropical cyclones, and it has the features of a tropical cyclone and a mid-latitude cyclone. So it's kind of a weird chimera of the two. So like a tropical cyclone, a subtropical cyclone does not have a front associated with it, but it can form over subtropical or tropical water, and it has that typical, well-defined area of low pressure in its center, surrounded by strong surface winds like what we see in a tropical storm or in a hurricane. Now, while they don't have fronts, they get their energy from the same areas that a cold front will. So you need that temperature radiant for a cold front to form. You need that same kind of thing for a subtropical cyclone.BB: And now we have a much better understanding of exactly what a mesocyclone is thanks to this edition of Science Behind the Forecast with WAVE 3 meteorologist Tawana Andrew. Thanks for the knowledge, Tawana. TA: Of course.This transcript was edited for clarity.