All too often, bad weather forces planes to make detours of hundreds of kilometers, sometimes creating delays that ripple nationwide. Help is on the way: this summer a new weather prediction system will come on line, allowing more precise air traffic routing, and even showing aircraft safe routes through storms-with a $45 million-per-year projected savings for airlines and travelers.

Designed at MIT's Lincoln Laboratory, the weather prediction system starts with an existing radar network, which covers large regions and updates information every six minutes. Air traffic controllers currently rely on this network to monitor weather in the areas between airports. The new system will incorporate both it and the two additional kinds of radar network that are currently used only to cover air space near airports, but which are more precise and send updates every four seconds. "Nobody had tried to stitch them together before" to cover air space between airports, says Jim Evans, an electrical engineer at Lincoln Labs and lead designer of the system. The technology adds information from satellites, which detect evolving storm clouds that aren't visible on radar, and provides a three-dimensional analysis showing where planes can fly above trouble spots.