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Hurricane tracking isn't an exact science

When it comes to forecasting the course of hurricanes, the only sure prediction is that there will be some unexpected twists.

That lesson was brought home with a vengeance in August, when Hurricane Charley hit Florida's Gulf Coast 70 miles (115 kilometers) south of where meteorologists thought it would make landfall just the day before.

"I think that there is the perception out there, because of the satellite photos and aircraft data, people do have faith in the technology — and sometimes that faith is too much," Max Mayfield, director of the National Hurricane Center, told reporters in Charley's wake.

It shouldn't be so surprising that hurricanes can be surprising — after all, they rank among the most violent and chaotic weather phenomena on Earth. Their fearsome power makes it difficult to get close enough to take an accurate reading. So how do meteorologists get the data they need for better predictions?

'Hurricane hunters' at work
The National Oceanic and Atmospheric Administration's "hurricane hunters" are in the front lines of the struggle to understand severe storms: They supplement satellite imagery by flying instrument-laden airplanes into the hurricane, in cooperation with NASA and the U.S. Air Force.

Since 1996, the hunters have been harvesting real-time data by dropping dozens of parachute-equipped instrument capsules, each about the size of a thick rolled-up newspaper, into the heart of each hurricane. The capsules, known as dropsondes, contain sensors to monitor pressure, temperature and humidity, plus a GPS locator device and a radio transmitter.

All those readings are fed into modeling software at the hurricane center, and that's where things really get tricky. As with most chaotic systems, a small change in a variable can mushroom into a huge difference in the result. That's what makes hurricane forecasting an inexact science.

"We have not yet been able to determine with certainty, beyond maybe 100 miles, a day before the storm, where that center is going to cross the coastline," meteorologist Fred Gadomski of the Penn State Weather Center told NBC News.

What makes a hurricane tick?
Some scientists are looking beyond the issue of tracking the next hurricane, focusing instead on what makes a hurricane tick. For example, the Tropical Rainfall Measuring Mission, which NASA recently extended through the rest of the hurricane season, is providing satellite-based "CAT scans" of severe storms.

At the Colorado-based Center for Severe Weather Research, lead scientist Joshua Wurman is interested in how a hurricane evolves once it makes landfall.

"Drastic changes occur with a hurricane as it comes on land," Wurman explained. For example, some hurricanes turn into major rainmakers, leaving dangerous floods in their wake. And all six of the hurricanes that Wurman has studied so far seem capable of whipping up "windstreaks," gusts of super-strong wind that may set the patterns for the storm's destructive power.

Wurman plans to do further research into windstreaks during the current hurricane season.

"We're trying to first confirm that these things really are present all the time," he said. "Are they stronger in some storms, weaker in others? We're at the beginning of our study on this, and there aren't many chances to see it."

Chasing the storm
So this week, while hundreds of thousands of people were fleeing Hurricane Frances, Wurman and his fellow researchers were heading for the front lines. The researchers are scouting out locations near Florida's coast for their radar-equipped "Doppler on Wheels" trucks.

"The goal is basically to park them where the eye is going to come on shore or just to the right of where it comes on shore," he said.

It sounds risky, and Wurman always advises others not to try this at home. But he has confidence in his fleet.

"The strongest winds we've seen are over 100 [miles per hour], and the trucks do fine," he said. "Certainly if it was a Category 5 storm, we would have concerns, mainly for airborne debris."

The bottom line? "The main thing is just to plan smart," Wurman said.

This report is an updated version of a from Aug. 16, 2004.