Weather Wise

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WEATHER satellite technology is improving rapidly. Yesterday this column featured a new orbiting instrument that has provided a mine of valuable information about thunderstorms. Now, a report in this week's edition of New Scientist magazine shows how rain and flood forecasts will be made much easier from now on thanks to yet another ingenious weather station spying on the clouds far below.

By measuring humidity levels within clouds, the Advanced Microwave Sounding Unit, built by the Anglo-French aerospace firm Matra Marconi for the Met Office, forecasters will have a much better idea if, when and where a downpour is likely to occur, and in what intensity. Up to now, the Met Office, which provides weather forecasts for the national media, has relied on data sent in by weather ships and land radar stations, but the new satellite will give global coverage. Satellites have been able to measure cloud cover for some time, but this is the first instrument that is able to peer inside clouds and get a picture of its internal temperature and humidity levels - essential if you want to know if the cloud is capable of generating a downpour.

Next month, the satellite will start feeding data to the Met Office; by the end of the year, full use of the data will be made as the figures are fed into the Met Office's forecasting computer model.

Will this mean more accurate forecasts after the evening news? Almost certainly, yes. People are still very sceptical about the predictions supplied by the Met Office and others, often citing Michael Fish's unfortunate assertion in October 1987 that no hurricane was on the way. In fact, up to about five days, forecasts are usually bang on the money. The challenge is now to extend this accuracy to the long range forecast.