PHOTO: JOE SKIPPER/Reuters/Landov

It was the evening of 26 August 2005, and Hurricane Katrina was barreling toward the Gulf Coast of the United States. Weather models were predicting that the center of the huge and devastating hurricane would slam directly into New Orleans in two and a half days. But New Orleans officials, perhaps recalling false warnings in the past, didn’t order a mandatory evacuation until the morning of 28 August—too late to do much good. The prediction was just 50 kilometers and a few hours off target. It is now painfully clear that an evacuation order ought to have come a lot sooner.

It was an all-too-rare example of a forecasting bull’s-eye. Just a month later, the two- to three-day forecast of Hurricane Rita’s path showed the storm hitting Houston; hundreds of thousands of people evacuated, or at least tried to, but it missed the city entirely. An accurate forecast of Rita’s path would have prevented an enormous amount of disruption and even death—a bus accident during the evacuation killed 23 people.

Help is on the way. Within the next 10 years, the two- to three-day hurricane forecast will be as accurate as the generally spot-on 24-hour forecast is today. Even more important, from the viewpoint of emergency officials, the four- to six-day forecast will give solid and reliable information to base evacuation orders on. Fatalities and false alarms will be avoided. Billions of dollars will be saved every year, in all probability. And it’s not just hurricane prediction that will get better; forecasts for rainfall, heat waves, blizzards, and even day-to-day temperatures will all get much better.

Three things are going to foment this revolution in forecasting accuracy: supercomputers, satellites, and advances in the scientific understanding of how weather evolves. Supercomputer processing power, for example, is projected to increase 16-fold during the next decade, from today’s 2 trillion floating-point mathematical operations per second to a speed approaching 32 trillion flops a second.

By then, nine additional advanced weather-specific satellites will likely join the fleet orbiting Earth, providing the first direct measurements of winds and the structure of clouds. And all that data and computer power will be used to better effect as a result of research already under way on the details of how storms gather force.

In a sense, the improvements will continue a trend that has been going on for half a century. Today’s five-day weather forecast, for example, is just as accurate as the three-day forecast was in 1976 and the 36-hour forecast in 1955. And the three-day forecast position of hurricanes is now as accurate as the two-day forecasts were 25 years ago. That means today, 72 hours before a hurricane strikes land, meteorologists can predict its landing point within 100 km, about a 1-hour drive on an expressway.