by Nate Silver
From the inside, the National Centers for Environmental Prediction looked like a cross between a submarine command center and a Goldman Sachs trading floor. Twenty minutes outside Washington, it consisted mainly of sleek workstations manned by meteorologists working an armada of flat-screen monitors with maps of every conceivable type of weather data for every corner of the country. The center is part of the National Weather Service, which Ulysses S. Grant created under the War Department. Even now, it remains true to those roots. Many of its meteorologists have a background in the armed services, and virtually all speak with the precision of former officers.
They also seem to possess a high-frequency-trader’s skill for managing risk. Expert meteorologists are forced to arbitrage a torrent of information to make their predictions as accurate as possible. After receiving weather forecasts generated by supercomputers, they interpret and parse them by, among other things, comparing them with various conflicting models or what their colleagues are seeing in the field or what they already know about certain weather patterns — or, often, all of the above. From station to station, I watched as meteorologists sifted through numbers and called other forecasters to compare notes, while trading instant messages about matters like whether the chance of rain in Tucson should be 10 or 20 percent. As the information continued to flow in, I watched them draw on their maps with light pens, painstakingly adjusting the contours of temperature gradients produced by the computers — 15 miles westward over the Mississippi Delta or 30 miles northward into Lake Erie — in order to bring them one step closer to accuracy.
These meteorologists are dealing with a small fraction of the 2.5 quintillion bytes of information that, I.B.M. estimates, we generate each day. That’s the equivalent of the entire printed collection of the Library of Congress about three times per second. Google now accesses more than 20 billion Web pages a day; the processing speed of an iPad rivals that of last generation’s most powerful supercomputers. All that information ought to help us plan our lives and profitably predict the world’s course. In 2008, Chris Anderson, the editor of Wired magazine, wrote optimistically of the era of Big Data. So voluminous were our databases and so powerful were our computers, he claimed, that there was no longer much need for theory, or even the scientific method. At the time, it was hard to disagree.
But if prediction is the truest way to put our information to the test, we have not scored well. In November 2007, economists in the Survey of Professional Forecasters — examining some 45,000 economic-data series — foresaw less than a 1-in-500 chance of an economic meltdown as severe as the one that would begin one month later. Attempts to predict earthquakes have continued to envisage disasters that never happened and failed to prepare us for those, like the 2011 disaster in Japan, that did.
The one area in which our predictions are making extraordinary progress, however, is perhaps the most unlikely field. Jim Hoke, a director with 32 years experience at the National Weather Service, has heard all the jokes about weather forecasting, like Larry David’s jab on “Curb Your Enthusiasm” that weathermen merely forecast rain to keep everyone else off the golf course. And to be sure, these slick-haired and/or short-skirted local weather forecasters are sometimes wrong. A study of TV meteorologists in Kansas City found that when they said there was a 100 percent chance of rain, it failed to rain at all one-third of the time.