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Tracking Hurricanes

October 1, 2003 at 12:00 AM EDT


BETTY ANN BOWSER: This is the eye of Hurricane Isabel as it moved toward the Atlantic coast last month, packing winds of over 100 miles per hour.

ERIC CHRISTENSEN, National Weather Service: That was very dark, very turbulent, rough ride right in the eye wall.

BETTY ANN BOWSER: Eric Christensen is one of the meteorologists who flew through the eye of the storm.

ERIC CHRISTENSEN: That all of sudden turned into the eye, and the skies cleared and we were in sunshine with blue sky above us. And Isabel had a very beautiful eye. It had what we call “the stadium effect,” where it looks like you’re standing on the 50-yard line of a football field in a very large stadium, and you can see the cloud formations look like the stands, like the seating in a stadium.

BETTY ANN BOWSER: It wasn’t just hurricane voyeurism. It gave scientists important information to make weather forecasts for millions of people along the Atlantic seaboard, forecasts that resulted in life-and-death decisions: When to board up houses; when to evacuate. Those forecasts were so accurate that the death toll from Isabel was low.

Modern hurricane science started in the 1960s, with the advent of satellites that could beam pictures of the atmosphere back to earth for meteorologists to use to predict weather. Since then, there have been great advances, newer, more sophisticated satellites that are propelled into space, like NASA’s shuttle, high-tech ocean buoys that can record ocean currents and conditions. Computers and airplanes are all helping the National Hurricane Center in Miami produce more accurate and more long-range forecasts.

MAX MAYFIELD, National Hurricane Center: You’ve got to let me know how I can help you.

BETTY ANN BOWSER: In fact, in the past ten years, hurricane center director Max Mayfield, and his colleagues, have improved their record on predicting hurricane tracks by 20 percent.

MAX MAYFIELD: This is the first year that the National Hurricane Center has issued a five-day forecast on tropical storms and hurricanes. And we issue a five-day forecast every six hours, and we’ve looked at the verifications already, and they’re on the track on Isabel. There were actually very good. And I think the fact that we did have such a good five-day forecast did help people have some extra time to prepare, and then as it got closer, to go ahead and make all their preparations to protect life and property.

BETTY ANN BOWSER: Reconnaissance and surveillance airplane flights were crucial in making those accurate Isabel forecasts. The planes carry banks of computers able to take in data from the visual observations of the meteorologists on the planes. They also send these tubular-shaped objects, called dropsondes, into the storm.

SPOKESPERSON: Three, two, one, launch.

BETTY ANN BOWSER: They’re so-named because they are literally shot and dropped out of the belly of the aircraft.

MAX MAYFIELD: This is released from the aircraft at what ever flight what level the plane is and then drops down to the surface and sends back pressure, temperature, humidity and wind every half a second. So the jet, the NOAA jet aircraft flying in the environment around the hurricane, will release maybe 30 of these on a typical mission.

BETTY ANN BOWSER: Data from the drops are relayed by computers on board to NOAA’s super computers in Maryland, where they are analyzed.

COMPUTER ANALYST: Was the GFTL model showing intensification?

BETTY ANN BOWSER: Naomi Surgi is a hurricane project leader.

NAOMI SURGI, Environmental Modeling Center: Those flights dropping those instruments in the environment of the storm, the analysis it produces then is used to forecast the future motion of the hurricane. Those flights are fundamentally important to predicting the future tracks of hurricanes.

BETTY ANN BOWSER: The super computers send hurricane information down to Miami, to the National Hurricane Center where it’s read by a meteorologist, like Bob Korose.

BOB KOROSE: In this case, they had 128 knots of wind, and then it tells you an item here — 942 millibars. That’s the information that the dropsonde determines by falling into the center of the storm at the surface that’s the sea level pressure. And the lower the sea level pressure, the stronger the storm.

BETTY ANN BOWSER: Much of the data that winds up at the hurricane center in Miami is put into numerical computer models, the newest technology making forecasts more accurate.

Simply put, a numerical computer model is a mathematical expression of what’s going on in the atmosphere. But they are some of the most complicated computer programs on the planet.

FRANK MARKS, Hurricane Research Division: If you think Microsoft operating system is complicated, think about a model that’s trying to represent the atmosphere globally with all these processes. You know, you’ve got the rain, you’ve got the evaporation and condensation, you’ve got the thermal structure, you’ve got land surfaces, you’ve got water surfaces, you’ve got to have all the exchange of energy, you’ve got to have evaporation over land, evaporation over water, it’s a very complicated process. This program is very complicated. They run on the biggest, fastest computers in the world.

BETTY ANN BOWSER: And it takes a scientist like Rick Knabb, in charge of science operations at the hurricane center, to explain how a mathematical model can help forecast weather.

RICHARD KNABB, National Hurricane Center: What we are looking at is a graphical representation of a grid of data in three dimensions produced by a computerized representation of the atmosphere that’s run on a super computer. What looked like little nails here on the map are actually wind barbs that show you the direction from which the wind is blowing at any given location, and the more barbs you get at the end of the stick there tell you what the wind speed is.

BETTY ANN BOWSER: In the end, all this data from satellites, airplanes, and numerical computer models, goes to the meteorologist on duty at the Hurricane Center to make a forecast. It goes out to television stations, radio outlets, and other media around the country.

CHUCK BELL, Meteorologist: Check it out in motion here over the last couple of hours, the storm had been traveling north-northwest for quite a while…

BETTY ANN BOWSER: But even with all of the technological advances, hurricane scientists still don’t know how to predict the most dangerous product of a hurricane: Its intensity.

FRANK MARKS: The reason intensity’s critical is because the wind damage, the storm surge, and the waves, the run-up, are all driven by the wind, the wind strength, and that’s driven by the intensity. In the Isabel case, we had a very good track forecast. We knew where the storm was going almost four or five days ahead of time. But we couldn’t tell you what its strength was going to be there.

MAX MAYFIELD: We still need to work on intensity forecasting. I’m not even sure we even know exactly what we need. But one thing, we think we need better observations in the core of the hurricane itself in three dimensions. We need to get that information into high resolution computer models, and then we’ll have a chance of getting a better intensity forecast.

BETTY ANN BOWSER: And Mayfield says until they can do that, he worries about a worst-case scenario.

MAX MAYFIELD: My worst nightmare would be people going to bed with a Category-1 hurricane and waking up the next morning to, say, a Category-4 hurricane. If people had responded to that Cat-1 and we don’t catch the intensification, it can be an absolute disaster. We could have people stuck in cars and make no mistake about it, we know what will happen. There will be loss of life and there are some areas of the U.S. coastline the loss of life would bear into the hundreds, if not a few thousands.

BETTY ANN BOWSER: NOAA’s computer modeling expert Surgi says the answer will come from the constantly improving data NOAA’s aircraft get.

NAOMI SURGI: That information is vital. We’re not able to model the actual storm circulation. But we’re getting there, and the ability to be able to do that is really what’s going to help us improve intensity forecasts.

BETTY ANN BOWSER: There is urgency in finding an answer. Climatologists say the ocean and atmospheric conditions over the next 20 years will produce powerful hurricanes with high winds and storm surges that haven’t been seen in three decades. One theory to explain that projection is a one degree temperature increase in the water of the Atlantic Ocean.

FRANK MARKS: Now, what I challenge my people who came up with this signal is, “why?” Tell me why if the Atlantic on the average is one degree warmer do we get twice as many hurricanes? I mean, it just doesn’t make sense to me as a scientist that a one-degree change in the temperature, which is usually warm enough for a hurricane anyway to form, would mean that there’s so many more.

BETTY ANN BOWSER: What’s the answer?

FRANK MARKS: Well, the answer is we’ve got to find out. I mean, we don’t know.

BETTY ANN BOWSER: Not only are scientists expecting more hurricanes, more people are moving each year to coastal areas where they hit. And with each new big storm damage figures escalate. Isabel caused more than $10 billion of destruction.