BioEd Online

Hurricane Rita is bearing down on the coast of Texas, and its winds of 270 kilometres per hour threaten to batter the state this weekend. The latest forecasts describe Rita as 'potentially catastrophic'.

President Bush has declared a state of emergency in Texas and Louisiana, and up to a million people are now being evacuated from Houston and Galveston County. Many oil rigs and refineries around the coast have been abandoned, threatening to send US oil prices soaring. Meanwhile, NASA has closed the Johnson Space Center in Houston, and transferred International Space Station operations to Russian mission control in Korolev, near Moscow.

After Hurricane Katrina, which devastated New Orleans and its environs on 29 August, the six-man team of specialist forecasters at the National Hurricane Center in Miami, Florida, are under more pressure than ever to predict where Rita will make landfall. Here, news@nature.com talks to team manager Chris Burr.

How are your forecasters bearing up under the pressure?

They're working harder than the normal 40 hours a week, and doing extra shifts. Their shifts are eight or nine hours, and because we provide 24-hour coverage many of them work overnight. They're a little fatigued right now.

How do they come up with the forecast?

When the specialists start their shifts they're briefed by their predecessors, and then start collecting data from ships and buoys in the Gulf of Mexico. They also collate information from aircraft reconnaissance flights, and get updated satellite images every 30 minutes. All of this gives them a wind speed and direction, sea heights and atmospheric pressure. They also have a conference call with other meteorologists around the Gulf to discuss the data that will go into computer models that predict the hurricane's path.

The specialist uses at least a dozen hurricane models, and sometimes results diverge. The models can take a system north or west, every which way. The skill of the specialist is to pick the most likely outcome. From start to finish it's about a three-hour process to produce a forecast.

Where do you think Rita will make landfall?

The latest track has it hitting the coast of central Texas, about 160 kilometres below Houston or so. We're predicting landfall by 7 am local time (11 am GMT) on Saturday 24 September. Typically our forecasts are very accurate three days in advance, although right now the cone of uncertainty covers most of the Texas coast.

Is there any chance the storm could peter out before it reaches the coast?

Rita looks like a category five at the moment. Although storms don't tend to maintain that intensity for long, it's definitely going to strike land as a hurricane.

Even if it goes down to a category one, with winds greater than 118 kilometres per hour, that's certainly strong enough to do damage. Katrina was a category one when it hit southeastern Florida, and it uprooted trees and damaged cars and houses here.

How certain can you be?

Forecasting the tracks of hurricanes has become a lot more accurate over the past few years. For Katrina we got it almost exactly right.

Direction forecasting has been improved by better computing power, more data from ships and buoys to put into the models, and advances made in those models by researchers.

Intensity forecasting is another matter. At the moment it's difficult to predict what category hurricanes will be when they hit land. We're trying to improve that by getting the National Oceanic and Atmospheric Administration and Air Force airplanes that fly over the storms to make observations, to take pressure readings and also drop sounders into the hurricane to get measurements from inside.

Has this hurricane season seen record activity?

I think this is the fourth most active Atlantic season on record. The hurricane season ends on 30 November, but activity will peak around 20 October, so it's more than likely there will be two or three more named systems by the end of it.

Is it unusual for Texas to be in the firing line?

It's been a while since a major hurricane reached Texas. I think the last one was Hurricane Carla, which hit in 1961. They're certainly infrequent.

[Editor's note: Hurricane Carla was a category-four storm that caused more than 30 deaths. Arguably the worst US natural disaster was from a hurricane that hit Galveston, Texas, in 1900, killing at least 8,000 people.]

What do the forecasters do when the hurricane season ends?

We issue forecasts for all Atlantic and eastern Pacific tropical storms year round, but after November they tend to be marine warnings for shipping. After 30 November the six hurricane specialists go back to doing research. There are also plenty of hurricane conferences in the winter. Other divisions of the National Hurricane Centre continue issuing forecasts for other parts of the world.

You're based in Florida, very close to the action. Does that ever make you nervous?

Yeah, I look at what's coming our way every day at this time of year. Sure I get nervous: I have a house and car that I have to protect just like everyone else.