Electronic Weatherman

Weather forecasters are earnest men who do their best. They pore over floods of figures on-pressure, temperature, humidity and wind velocity. They consult the precedents like judges reaching back for past decisions. Sometimes they take a deep breath and predict warm, sunny weather--and get rain and snow instead. When the mess is being cleaned up, the amateur weather prophets claim they knew what would happen all along: they felt it in their rheumatism.

Year in & year out, the official weather men do a much better job than the amateurs with their rheumatism, but the professionals' spectacular failures are remembered long after their normal successes have been forgotten. Their trouble is that in trying to avoid failures they have run up against an obstacle created by themselves. The observation methods of modern meteorology pull so many figures out of the air that no human brain or combination of brains can digest them all in time to make a fully considered forecast.

Last week the U.S. Weather Bureau, Air Force and Navy told how they hope to turn the job over to an electronic brain. The theory has been worked out at the Institute for Advanced Study, and electronic computers will soon be available that can handle the figuring load. The machine will get a set of mathematical equations. The latest meteorological figures from most of the U.S. and 1,000 miles out into the Atlantic will be fed into it.* Then the machine will start computing. In less than two hours, it will follow 40 million "instructions" and arrive at a 24-hr, forecast. The same job, using all available figures, would take a human weatherman 10,000 times as long.

The bureau is setting up its "Numerical Weather Prediction Unit" with a staff of 30 to serve the machine. It has high confidence that the method will be in practical use by next fall. But to prove its effectiveness, the bureau plans to give it a really hard test. Its first job will be to digest the weather information that was available just before last Nov. 6, when the bureau predicted fair weather for the U.S. Northeast--and a howling blizzard blew in off the sea. If the machine predicts correctly the unexpected wind-shift that made monkeys out of the weathermen, it will get a steady job with the bureau.

* Information from the Atlantic will be meager because of the recent Government decision to withdraw U.S. support for the Atlantic weather ships (TIME, Nov. 2).

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