The Perils of Prediction/Forecasting is No Picnic; Weather; Scientific American Presents; by Monastersky; 8 Page(s)

Last summer a gaggle of government dignitaries flocked to the end of Thunder Road, a quarter-mile-long strip of asphalt tucked behind Washington Dulles Airport. There, in the shadow of a giant radar dome, the bureaucrats celebrated the end of a nearly 20-year struggle to bring the National Weather Service (NWS) into the information age. This $4.5-billion modernization effort has furnished U.S. federal forecasters with sophisticated Doppler radar, a nationwide communications network, vastly improved computing power and a new suite of satellites.

To test-drive the revamped system, I enlisted the full force of the weather service to answer a simple question: Will it rain on an upcoming picnic planned for my son's birthday in early October? For a 10-day period before the event, I turned into a weather weenie, keeping in close contact with meteorologists drawing up the forecasts for Saturday, October 9. Aside from helping me plan the picnic, the exercise allowed the weather service to show off its advanced capabilities and to explain exactly how meteorologists go about predicting the weather.