Gaps in the vast panorama of world weather are being filled in as the Global Weather Experiment, a unique year-long scientific effort to monitor the earth's oceans and atmosphere, enters its final phase. During a recently ended 2-month ‘special observing period,’ an array of ships, aircraft, satellites, buoys, and balloons supplied massive amounts of new information from the water-covered expanses of the tropics and southern hemisphere. Conditions in these regions, largely unobserved until now, have a profound impact on weather elsewhere in the world.

By the time the experiment winds up this year, meteorologists will have the most complete global weather record ever assembled. Using this day-by-day account, they will try to calculate the practical limits of forecasting and design a world weather observing system to achieve these limits.