Gauging Hurricane Rita's Strength
MICHELE NORRIS, host:
Meantime, in the warm Gulf waters west of Florida, another storm is gaining strength. Hurricane Rita is now a Category 5 storm with top winds around 165 miles an hour. Rita is tracking westward toward the Texas coast. To better understand what's powering Rita, we called Chris Landsea. He's a science officer at the National Hurricane Center in Miami.
Dr. CHRIS LANDSEA (Science Officer, National Hurricane Center): Warm water is one of the key ingredients for intensification of hurricanes, but it's not the only part. You also need very moist air. You need an unstable atmosphere to allow thunderstorms to develop. And probably most importantly, you need a lack of wind shear, which is changing winds with height. And over the last couple days, Rita has encountered all those key ingredients.
But even though it looks like it's very warm throughout the whole Gulf of Mexico, the subsurface waters are very much mixed. But you have some areas that are cool in the subsurface and some that are very warm, 'cause there's a pocket called the loop current which is part of the Gulf Stream circulation. Currently, the storm is over that, and it's feeding off that very warm, very deep water. But there are portions of the western and northern Gulf of Mexico that don't have warm water that extends to a depth, that it's cool below, so that's one hope that if the storm mixes some of this cool water up that it would be kind of self-limiting on how strong it could get.
NORRIS: So what does that mean for the communities all along the Gulf Coast?
Dr. LANDSEA: Well, what it means is that, well, you have a major hurricane in the Gulf, and it's not--it's going to hit somewhere where there's people living, and we have to start preparing for when that makes landfall sometime Friday night or Saturday morning.
NORRIS: At what point will you be able to call officials in the towns and the cities and the jurisdictions and give them some sort of fairly accurate predictions on what they might face?
Dr. LANDSEA: Yeah. Well, at this point, the cone of uncertainty extends from about the Texas-Mexico border up through the western third of Louisiana, which puts Texas in the area of highest risk. Because a two-and-a-half-day forecast would still have an average error of about 125 to 150 miles, we'd rather not specify exact spots. So really interests all along from Brownsville to the western third of Louisiana need to pay very much attention to what's going on.
NORRIS: Looking at the map, that's a huge area that you're describing.
Dr. LANDSEA: That's right, but it does reflect the true uncertainty of making a two-and-a-half-day forecast. These predictions have gotten a lot better over time. In fact, they're 50 percent smaller error compared to just 15 years ago, so they're improving, but by no means are they perfect.
NORRIS: Well, since it's out over the open water, how do you monitor that?
Dr. LANDSEA: Well, we have a variety of tools for doing that. We do have land-based radars that are able to give estimates of what the rain and position is. We are doing that through about noon today from the Key West radar. We also have a variety of aircraft that fly into the hurricane to take actual measurements of what's going on. We have a fleet of satellites that are peering down on the Earth to measure the position of the storm and get an idea of the size of the extent of strong winds as well.
NORRIS: You know, this is an area where you've got a lot of bays and a lot of inlets and a lot of sort of islands, long rectangular islands there along the Gulf Coast. Are they particularly vulnerable?
Dr. LANDSEA: Oh, certainly. Because the waters are fairly shallow offshore, that accentuates the storm surge problem. And we saw that dramatically with Katrina along the Mississippi coast in particular. And so if this does come ashore as a Category 3, 4 or 5, we're going to see a very high storm surge and a very big impact because of that.
NORRIS: Chris Landsea, thanks so much for this information.
Dr. LANDSEA: Yeah, glad to help out.
NORRIS: Chris Landsea is a science officer at the National Hurricane Center in Miami.
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