MICHEL MARTIN, HOST:
As we just heard the flooding from the storm is taking a toll on many families, especially those waiting to be rescued. But now we wanted to take a step back and try to get some historical context about the storm and get a sense of why this is so different from past storms. So we're joined now by Neil Frank. He's the former director of the National Hurricane Center. He also served for more than 20 years as chief meteorologist for KHOU in Houston. He's with us now from his home, which is about 40 miles west of Houston. Neil Frank, it's good to talk with you. Thanks so much for speaking with us.
NEIL FRANK: Well, thank you very much.
MARTIN: Can you give us a sense of how Harvey compares to other hurricanes that have hit Texas and the United States in recent years?
FRANK: Yeah. Well, let me put this in perspective. First of all, there's several things - three things that we worry about in a Hurricane. Number one is the storm surge. Number two, you have the wind. Then number three, it's the rainfall. Now, the amount of rainfall that you get with a hurricane is not a function of how strong it is. It's a function of how fast it's moving. I don't mean the wind speeds. I mean the forward motion. And if it stalls, then you're going to get inches, tens of inches and maybe feet of rain.
MARTIN: So we really can't know right now how bad this is because it's still going on. Am I right?
FRANK: Yeah.
MARTIN: I mean, the rain's still going on. There's still flooding. It could get even worse.
FRANK: Absolutely.
MARTIN: OK, so there have been several major storms over the last decade and a half. And I think people remember there's - Katrina in 2005, Superstorm Sandy in 2012 and then there was Hurricane Ike in 2008, which is still the third costliest storm in the country's history. So it really invites the question - does Texas have any plans in place to prevent the sort of flooding that we're seeing?
FRANK: OK, now all of the three storms that you just mentioned were all storm surge storms or wind storms - had nothing to do with the heavy rains. This is a heavy rain situation. Now, you can do something about storm surge. For example, one of the things that's being considered here in the Houston area is to build what is called an Ike Dike after Hurricane Ike. Or you would put a 17-foot seawall down along the beaches so that the water can't come up into the Galveston Bay. You could do something like that also in terms of Sandy - very expensive. But that gives you the protection against the storm surge. And it would give you no protection against the kind of rains that we're experiencing here.
Now, what happened is the center of the storm moved in. It stalled about 100 miles inland. And it's just sitting there spinning around. Why is it not moving? Because there's no steering currents. The steering currents have just literally dissipated. And when you have a hurricane with no steering currents, it's like a spinning top. When you put - spin a top out on a table, it doesn't just stay stationary, it wobbles around. And that's what the center is doing. It's just wobbling around. And it looks like it's going to wobble around for another two, three, maybe four days.
MARTIN: What causes a storm system to stall like this one has?
FRANK: Hurricanes tend to move along in what I like to call rivers of air. The major river in the tropics is the trade winds. The trade winds blow from Africa all the way over to North America. And if you put a hurricane out in the trade winds, they move along at 10, 15 miles an hour. And as they move towards the western Gulf of Mexico, the trade winds begin to die down and they begin to weaken. And when they do that, then you have a situation like we have today. And there's no river. The river's dried up.
Now back to your initial question. Why haven't we done something in Houston to minimize this kind of rainfall? You could - you could go and dredge big, big channels down through the area here so the water would run off faster. But again, it's billions and billions of dollars. I guarantee you that the community is very sensitive to this kind of rainfall. And they've done everything they can within reasonable economic limits to try to minimize this kind of rain. But when you get the kind of rainfall we have now, it's just very, very difficult to build a structure that would prohibit that.
MARTIN: That's Neil Frank, former director of the National Hurricane Center. Thanks so much for joining us.
FRANK: Bye now. Transcript provided by NPR, Copyright NPR.