A subtropical cyclone is no ordinary storm. WAVE 3 meteorologist Tawana Andrew explains on this edition of "Science Behind the Forecast."
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've heard of hurricanes and tropical storms, but I'm bringing everyone a different type of system that they may not have heard about.
BB: Yeah, this one is certainly new to me, subtropical cyclone. What do we need to know about it?
TA: Well, diving into the National Hurricane Center's definition, which, of course, is a little complicated...
BB: But always fun.
TA: It defines a subtropical cyclone as a non frontal low pressure system that has characteristics of both a tropical and extra tropical cyclone. And like tropical cyclones, they are non frontal with synoptic scale cyclones that originate over tropical or subtropical waters.
BB: Exactly how I would have put it.
TA: So put that in English, it is basically a weird weather hybrid. It forms from an extra tropical storm, and these technically have colder temperatures in the upper levels of the atmosphere compared to what you see in a typical tropical storm. And with extra tropical storms, they typically sweep across the country with warm fronts and cold fronts. So it's that type of system that we typically see, you know, bringing us snow or rain or thunderstorms like that, that you can have form into a subtropical cyclone. Now, these subtropical storms don't have the actual fronts with them, but they will exist in the same latitude ranges as the typical extra tropical storms. So think a tropical system just further north than what you would typically see. So for these kind of systems as well, they have colder upper level temperatures, which means they can form in areas with cooler ocean temperatures, which really plays a role in when we can see them. A subtropical storm can form either earlier or later than your typical hurricane or tropical storm, since the warm water is not really necessary. But here's the fun part, once a subtropical system travels into a warmer area, then it can transition into an actual tropical cyclone.
BB: Okay, kind of a chameleon storm.
TA: Basically, it can be whatever it wants to be, and we love it for that. Now, for a typical tropical system, like a hurricane, it's pretty symmetrical. We see everything kind of looking the same on each side, and with temperatures and dew points, they're pretty comparable throughout. But the thing is, with a subtropical system, it's very lopsided. It has warmer temperatures, higher dew points and more moisture on the eastern half. So all the clouds, showers, the thunderstorms, will mainly be east of the storm center. That also puts the thunderstorms further away from the center of a storm. That's how you can tell the difference, if you're looking at, let's say, satellite and radar, and the difference between a tropical system and a subtropical system. The thing is, with these types of system, with a subtropical system, the winds will never be that strong. They will stay, usually below 74 miles per hour, while an actual tropical cyclone can have wind gusts over 150 miles per hour. So the winds in a subtropical cyclone will be slower than what we typically see during rush hour in Louisville.
BB: It'll get passed on the freeway.
TA: Always.
