British Supercomputer Forecasts Weather Months in Advance

Everyone knows never to trust the weather report. But European scientists are using a supercomputer to predict the weather months in advance. And whether it's for bikinis or umbrellas, big-money businesses are taking notice.
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The computer is part of the European Center for Medium-Range Weather Forecasts (ECMWF). For the last few years, researchers there have been trying to do something that the weather's inherently random nature would normally preclude: forecast entire seasons. The results have become so reliable that Germany's National Meteorological Service (DWD), a member organization of ECMWF, now officially offers them for sale. For €150 ($231), companies can now purchase the center's six-month forecast.

For example, according to the center, this summer will be a little warmer than usual in Germany, although rain levels will remain about average. The reports from Reading are oracle-like in their simplicity, merely pointing out broad tendencies -- warmer, colder, wetter or dryer than average -- and for good reason. More information cannot be gleaned this far in advance. The forecasts only reveal the extent to which actual values could diverge from the averages of many years.

The computer still makes significant mistakes, and the information it provides is too vague for purposes like planning vacations. But the data can be of use to business, and the DWD is already advising power companies and municipal utilities. If they know, for example, that the upcoming winter is likely to be colder than usual, these companies can stockpile natural gas reserves for their power plants early on.

The number of economic sectors sensitive to the weather is surprisingly large, from ice cream makers to the textile industry. In the latter case, knowing whether summer temperatures are more likely to create a need for bikinis or windbreakers can be critical.

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Graphic: Weather predictions for summer 2008