This is a partial transcript of "The Big Story With John Gibson," March 31, 2006, that has been edited for clarity.

JOHN GIBSON, HOST: When it comes to these storms, you can leave your umbrella at home. A new series on the Discovery Channel takes a look at the worst weather imaginable and asks when is it going to happen here.

(BEGIN VIDEO CLIP)

UNIDENTIFIED MALE: If the conditions are changing very rapidly, changing in a way that has not been forecast, then there will be trouble.

(END VIDEO CLIP)

GIBSON: So, can it happen here, Jane?

SKINNER: Well, John, some say it's not a question of if but when, and the series is called "Perfect Disaster." It's really a docudrama, as they call it. It makes it pretty clear, if these megastorms would hit there would not be many pieces left to pick up.

Tim Marshall is a veteran storm chaser and took part in the making of "Perfect Disaster" for Discovery Channel. Tim, thanks for being here.

We should say off the top, when they say docudrama, this is not just pure fiction, it looks like it could be a Hollywood movie, a blockbuster, but there is a lot of science involved in these episodes, right?

TIM MARSHALL, STORM CHASER: Absolutely. Science is in part of this series for sure.

SKINNER: And tell me your role in all of this. You are a veteran storm chaser and have been doing this for probably almost years it looks like. What was your role? Were you a consultant here?

MARSHALL: Sure was. I am a storm chaser as far as a hobby is concerned and I ride out hurricanes and film tornadoes at close range.

SKINNER: And you are a meteorologist as well, right?

MARSHALL: That is correct.

SKINNER: Tell me, when we talk about perfect disaster, define for us, as a meteorologist, what is a perfect disaster? Is it something like a Hurricane Katrina? The tsunami? What falls in that category?

MARSHALL: Actually Hurricane Katrina was a perfect disaster. I mean, if you go down there today there are still neighborhoods that are completely destroyed. Just as they were the day before the hurricane, as they board them on up and the hurricane comes along and destroys it.

SKINNER: And what makes a perfect disaster? Is it just the perfect storm as we think about in meteorological terms or do other things come into play?

MARSHALL: Well, there are sort of other things that do come into play. First of all, we did have the levee system in New Orleans and we did have a failure there and then we have a cascading kind of effect, you know, it's very difficult to get into these areas once a disaster like that happens. So it sort of feeds on itself and compounds itself and that's what the "Perfect Disaster" series shows.

SKINNER: This series, the one we are looking at here, is the city of London is basically submerged by what they call a megaflood they also have one of the episodes on a super tornado that bears down on Dallas, they have a solar storm that threatens New York City. Tell me a little bit about those episodes and what was involved in terms of the science of it.

MARSHALL: Sure, I mean as far as Dallas is concerned, here we have a major city here in tornado alley and it's got a lot of glass-clad skyscrapers and there is nothing that will prevent a tornado like an F-5 to go through the city. And, in fact, cities have been hit. Downtown Fort Worth was hit in 2000 and other cities such as Nashville and Salt Lake City were hit with tornadoes, so this can happen and that's part of what the series is showing this can happen. It's not a question of if it's going to happen but when.

SKINNER: And how do we know when? Are we talking about in our lifetimes, the next 10 or 20 years?

MARSHALL: I think so. I think in the next 10 or 20 years we have another major city hit. New Orleans is already hurting from what happened with Hurricane Katrina. Could we have another hurricane this next season come in and undo the levees again? I think that's possible.

SKINNER: All right. So this series takes a look at all these different cities, mostly urban populations and what would happen if these megastorms hit. What did you learn about how prepared we are for something like this?

MARSHALL: Well, you know, the thing that really people tell me all the time is we thought we were prepared but then when it happens you really find out that you weren't as prepared as you thought. And a lot of people also thought that they never could be hit with such a disaster. I think we need to see that such a perfect disaster can happen.

SKINNER: Tim, your role in all of this was to teach the producers, you know, the science of it. When you were involved in it, though, anything that you learned from all of this from taking a look at such different types of disasters?

MARSHALL: Well, certainly I learned how good special effects can be. I mean, that's something I have learned a great deal about and there are phenomenal effects in these series.

SKINNER: And it sounds like they are pretty realistic, you think?

MARSHALL: Absolutely. In fact the tornado scene in Dallas was striking to me.

SKINNER: Wow! Tim Marshall, who is a veteran storm chaser, thanks very much. You were a consultant on Discovery Channel's "Perfect Disaster." It's on Sunday nights. Thanks.

John, scary stuff.

GIBSON: It is scary stuff. I don't know if I live high enough in the air to survive these things.

SKINNER: Hopefully we won't find out

GIBSON: Basement apartment has got to be worried. Jane Skinner, thanks very much.

Content and Programming Copyright 2006 FOX News Network, LLC. ALL RIGHTS RESERVED. Transcription Copyright 2006 Voxant, Inc. (www.voxant.com), which takes sole responsibility for the accuracy of the transcription. ALL RIGHTS RESERVED. No license is granted to the user of this material except for the user's personal or internal use and, in such case, only one copy may be printed, nor shall user use any material for commercial purposes or in any fashion that may infringe upon FOX News Network, LLC'S and Voxant, Inc.'s copyrights or other proprietary rights or interests in the material. This is not a legal transcript for purposes of litigation.