The Eastern Seaboard is warily watching the progress of Hurricane Irene, wondering what course the storm will take and just how ferocious it will be. Predicting the path of a hurricane still involves some guesswork—but thanks to rapidly improving computer models and data-gathering abilities, Tekla Perry reports in IEEE Spectrum, scientists are able to make more accurate forecasts farther in advance than they were even five or ten years ago. In fact, the predicted track of a hurricane over the next 48 hours today is as accurate as a prediction for the next 24 hours was 10 years ago—a day that can make a big difference for people deciding whether to evacuate and how to prepare before the storm. Boosts in computing power mean scientists can run more, faster, and more detailed simulations of the storm, and technologies like Dopper radar provide detailed data on wind speed, air pressure, and temperature as storms progress.

Irene has been a relatively easy storm to predict so far, Frank D. Marks Jr., a NOAA hurricane researcher, told Spectrum, but that doesn’t mean scientists are able to tell residents of any particular city exactly ...