WEATHER forecasting blunders, such as Michael Fish’s failure to foretell the Great Storm of 1987, will become increasingly rare, the Met Office predicted yesterday.
The introduction today of new computers that have eight times the processing power of current models will more than halve the number of wrong predictions, the forecasters said.
The facilities at the Met Office’s new headquarters in Exeter have allowed it to incorporate data from an advanced Nasa research satellite into weather bulletins for the first time.
Further improvements in accuracy are expected this summer when new “four-dimensional” forecasting software is introduced, tracking how the weather changes with time as well as geography.
A three-month trial of the new system has delivered spectacular results that have outstripped even the most optimistic projections of Met Office scientists.
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“We roughly halved the number of ‘busts’ forecast in the UK,” said Stephen English, the research manager in charge of the project. “It is one of the most exciting leaps forward in forecasting we have ever made.”
John Mitchell, the Met Office’s chief scientist, said: “We were expecting good results, but the magnitude of the improvements has been a pleasant surprise. The investment in improved technology has been made at the same time as our relocation, and it’s great to see the benefits.”
The biggest improvement will be seen in medium-term forecasts over two to five days, though short-term forecasts will also be refined in the near future. “UK consumers will see a big difference,” Dr English said. “It won’t help you decide whether you need a brolly today, but it will help you plan what you’re going to do at the weekend.”
Accurate medium-term forecasts are also the most important to many of the Met Office’s commercial customers, such as supermarkets which use the data to predict likely buying trends.
The key to greater accuracy lies in the use of data from Nasa’s Aqua satellite, which gathers more detailed information on temperature and atmospheric pressure and water vapour than has ever been available before.
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While microwave measurements of these variables have been used in Met Office forecasts since 1998, these are crude and can track changes only in vast volumes of air.
The infra-red instruments aboard Aqua, however, divide the atmopshere up into one-kilometre vertical layers, and can measure even very small changes in temperature or pressure in each of them.
This transforms the accuracy of the computer models used in forecasting, as it allows meteorologists to see changing weather patterns in unprecedented detail.
“We can now resolve the very fine structure of the atmosphere for the first time,” Dr English said. “An accurate initial estimate of the temperature of the atmosphere, at different levels and regions, is incredibly important to forecasting the future development of weather systems. Even very small differences in the analysis — of less than 1C — can make large differences to the forecast a few days later.”
“It doesn’t mean we’ll never get a forecast wrong, but we’re able to eliminate most of the really bad forecasts now,” Dr English said. “We can be much more certain when tracking a storm whether it will hit the UK, and when.”
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The Met Office started to include Aqua data in its forecasts on May 26, and the system has matched its trial performance in its first few weeks. Its new NEC SX-6 computers have been critical to the improvement: it was impossible to run both the Aqua and microwave data, which are both needed for the best results, on the old “Cray” computers. The new facilities will be formally opened today at a ceremony to mark the Met Office’s 150th anniversary.